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Chapter Outline

Cysts and Tumors of Odontogenic Origin

CHAPTER11

Odontogenic Cysts

Classifi cation �

Odontogenic keratocyst �

Dentigerous cyst �

Eruption cyst �

Gingival cyst and midpalatal raphe �

cyst of infants Lateral periodontal cyst �

Gingival cyst of adults �

Calcifying odontogenic cyst �

Nasopalatine duct cyst �

Nasolabial cyst �

Radicular cyst and residual cyst�

Solitary bone cyst �

Aneurysmal bone cyst�

Cysts of the salivary glands �

Developmental cysts of the head �

and neck

Odontogenic Tumors

Classifi cation �

Ameloblastoma�

Adenomatoid odontogenic tumor �

Squamous odontogenic tumor�

Calcifying epithelial odontogenic �

tumor Ameloblastic fi broma �

Odontoma�

Metastasizing malignant �

ameloblastomaAmeloblastic carcinoma�

Primary intraosseous squamous cell �

carcinoma

CYSTS OF ODONTOGENIC ORIGIN

INTRODUCTION

Kramer (1974) defi ned cyst as a pathological cavity having fl uid, semifl uid, or gaseous contents, which is not created by the accumulation of pus. It is frequently, but not always lined by epithelium.

True cysts: Cysts with epithelial lining.Pseudocysts: Cysts without epithelial lining.

Features of Jaw Cysts

Grow slowly, displacing rather than resorbing teeth. ●

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304ORAL MEDICINE: EXAM PREPARATORY MANUAL FOR UNDERGRADUATES

Symptomless, unless infected, and are frequently chance radiographic fi ndings. ●

Form compressible and fl uctuant swellings, if bone is perforated. ●

Appears bluish, when close to the mucosal surface. ●

Rarely large enough to cause pathological fracture. ●

Form sharply defi ned radiolucencies with smooth borders. ●

Fluid may be aspirated and thin-walled cysts may be transilluminated. ●

CLASSIFICATION OF CYST OF THE ORAL AND MAXILLOFACIAL REGIONS

Classify odontogenic cysts of the oral and maxillofacial regions.

Classifi cation of cyst of the oral and maxillofacial regions is given below:

Cysts of the Jaws

I. Gingival cyst of infants I. Odontogenic keratocyst II. Dentigerous cyst III. Eruption cyst IV. Gingival cyst of infants V. Gingival cyst of adults VI. Lateral periodontal cyst VII. Glandular odontogenic

cyst VIII. Calcifying odontogenic

cyst

I. Midpalatal raphe cyst of infants

I. Nasopalatine duct cyst

II. Nasolabial cyst

I. Radicular cyst, apical and lateral

II. Residual cyst III. Paradental cyst

and juvenile paradental cyst

IV. Collateral cyst

I. Solitary bone cyst

II. Aneurysmal bone cyst

Odontogenic cysts Nonodontogenic cysts

Developmental origin

Epithelial-lined cysts

Cysts of the jaws

Nonepithelial-lined cysts

Infl ammatory origin

I. Cysts Associated with the Maxillary Antrum

Mucocele ●

Retention cyst ●

Pseudocyst ●

Postoperative maxillary cyst ●

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305CYSTS AND TUMORS OF ODONTOGENIC ORIGIN

II. Cysts of the Soft Tissues of the Mouth, Face, and Neck

Dermoid and epidermoid cysts ●

Lymphoepithelial (branchial) cyst ●

Th yroglossal duct cyst ●

Anterior median lingual cyst (intralingual cyst of foregut origin) ●

Oral cysts with gastric or intestinal epithelium (oral alimentary tract cyst) ●

Cystic hygroma ●

Nasopharyngeal cyst ●

Th ymic cyst ●

Cysts of the salivary glands: Mucous extravasation cyst, mucous retention cyst, ranula, ●

and polycystic (dysgenetic) disease of the parotidParasitic cysts: Hydatid cyst, cysticercus cellulosae, and trichinosis ●

Frequency of odontogenic cysts occurrence is as follows:

Radicular cyst ●

Dentigerous cyst ●

Odontogenic keratocyst ●

Residual cyst ●

Paradental cyst ●

Lateral periodontal cyst ●

Calcifying odontogenic cyst ●

Gingival cyst ●

Eruption cyst ●

Glandular odontogenic cyst ●

Epstein’s pearl ●

ODONTOGENIC KERATOCYST

Discuss pathogenesis, clinical features, radiological features, and histopathology of odontogenic keratocyst.

Describe the mechanisms of cyst enlargement in odontogenic keratocyst.

Write a short note on histopathology of odontogenic keratocyst.

Explain keratocystic odontogenic tumor.

Give a detailed account of orthokeratinized odontogenic cyst.

Discuss nevoid basal cell carcinoma syndrome.

(Synonym: primordial cyst)Th e 1972 WHO classifi cation called it a primordial cyst. Th e 1992 WHO classifi cation called it an odontogenic keratocyst (OKC).Th e 2005 WHO classifi cation called it as

Keratocystic odontogenic tumor ( ● KCOT): Parakeratinized variant of OKC (more aggres-sive nature and high recurrence rate).

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Orthokeratinized odontogenic cyst ( ● OOC): Orthokeratinized variant of OKC (less ag-gressive nature and low recurrence rate).

Defi nition: Keratocystic odontogenic tumor is a benign intraosseous tumor of odon-togenic origin with a characteristic lining of parakeratinized stratifi ed squamous epithe-lium and potential aggressive, infi ltrative behavior. It may be solitary or multiple. Th e latter is usually one of the stigmata of the inherited nevoid basal cell carcinoma syndrome (NBCCS).

Variants of OKC: Depending on radiological appearance (Fig. 11.1)Envelopmental variant: ● Cysts that embraces unerupted tooth.Replacement ● variant: Cysts that formed in the place of a normal tooth. Extraneous variant: ● Cysts occur in the ascending ramus of mandible and away from the tooth. Collateral variant: ● Cysts occurs adjacent to the roots of teeth.

PathogenesisTh e sources of epithelium for cyst formation are: ●

Cell rests of Serre: Envelopmental variant of OKC. ❍

Degeneration of stellate reticulum in enamel organ: Replacement variant of OKC. ❍

Epithelial off -shoots (hamartias) of the oral epithelium from basal layer: Extraneous ❍

variant of OKC.Epithelial rests of Malassez: Collateral variant of OKC. ❍

Multiple OKCs were usually seen in patients with NBCCS. Th e cysts may arise ❍

directly from dental lamina in diff erent sites. Th e stimulus for this phenomenon is not known, but the NBCCS is transmitted genetically as an autosomal dominant disorder.

Clinical features: It occurs in two forms, i.e., central/intraosseous variant and peripheral/extraosseous variant.

Age ● : 20–40 years and 50–70 years (bimodal age distribution)

ab

c

d

Fig. 11.1. Variants of OKC: (a) envelopmental, (b) replacement, (c) extraneous, and (d) collateral.



Gender ● : Male predilectionLocation ● : Posterior region of the mandibleSigns and symptoms ●

Patients are remarkably free of symptoms until the cyst reaches larger size. ❍

Pain, mobility of the teeth, and paresthesia of the lower lip is frequently seen. ❍

Th e clinically observable expansion of the bone occurs late in OKC because it tends ❍

to extend in the medullary cavity of bone. In maxilla, the large-sized lesions may lead to displacement and destruction of or- ❍

bital fl oor and proptosis of the eyeballs.Discharge of pus may be seen due to secondary infection. ❍

Peripheral odontogenic keratocyst: ❍ It occurs on gingiva with clinical features similar to gingival cyst of adults and the histological features of a typical OKC. Multiple OKCs in the jaws are seen in some cases, frequently they are associated ❍

with the nevoid basal cell carcinoma syndrome (NBCCS) (also called as Gorlin–Goltz syndrome or the Gorlin syndrome). Th e syndrome is inherited as a set of autosomal dominant characteristics with strong ❍

penetrance and variable expressivity. Th e clinical features of NBCCS includes multi-ple nevoid basal cell carcinomas and OKCs, bifi d ribs, ectopic calcifi cations, plantar and palmar pits, central nervous system and ocular lesions, frontal bossing, ocular hypertelorism, and other congenital skeletal defects. Th e NBCCS gene is mapped to chromosome 9q22.3. In some cases, multiple OKCs may occur without the other overt features of the syndrome.

Radiological featuresIt shows well-defi ned unilocular or multilocular radiolucency (2.5:1) with smooth ●

(slow-growing lesions) or scalloped margins.Some of the unilocular lesions have scalloped margins and these may be misinterpreted ●

as multilocular lesions (scalloped margins suggests unequal growth activity in diff erent parts of the cyst lining). Th e mandibular lesions enlarge and extend to the other side of the bone by crossing the ●

midline. Th is is an important characteristic feature of OKC.Tooth displacement is commonly seen rather than root resorption. ●

Radiological variants of OKC: Mentioned earlier. ●

Peripheral odontogenic keratocyst shows saucerization of underlying bone. ●

Histopathology (Fig. 11.2)Th e cysts are lined by a parakeratotic or orthokeratotic stratifi ed squamous epithelium, ●

which is usually about 5–8 cell layers thickness without rete ridges. Basal layer consists of palisaded cuboidal or columnar cells with reversal of polarity, ●

whereas suprabasal layer composed of closely packed polyhedral cells.Th e parakeratotic epithelium may often show corrugated surface, which could be due ●

to unequal growth pattern of the lining at various areas.Infoldings of epithelial lining into the capsule with resultant inlets of the lumen or ●

crypts may be due to active proliferation of epithelium into the capsule. Th e attachment between epithelium and the connective tissue capsule tends to be weak, ●

which may cause separation in many areas.



Sometimes, satellite cysts or proliferating epithelial islands are seen in the capsule. ●

Th e cyst lumen contains desquamated keratin. ●

Th e presence of an intense infl ammatory infi ltrate in fi brous capsule may cause lose ●

of keratinization, thickening, development of rete ridges, or ulceration of overlying epithelium.

Diff erential diagnosisAmeloblastoma ●


Aneurysmal bone cyst ●

Prognosis and predictive factorsOKC is the most common recurring lesion than any other cysts of the jaws. ●

KCOT is a more aggressive lesion with high recurrence rate compared to OKC. ●

Recurrences were more frequent in NBCCS patients than cysts in nonsyndrome pa- ●

tients.OKCs enucleated in one piece recurred signifi cantly less often than cysts enucleated in ●

several pieces. Multilocular lesions recur more often than unilocular lesions. ●

Cysts treated with enucleation or marsupialization will have high recurrence rate than ●

surgical resection. Recurrent lesions may develop from epithelial off -shoots (hamartias) of the basal layer ●

of the oral epithelium. So, overlying surface epithelium should be excised with the parent cyst.

DENTIGEROUS CYST

Explain pathogenesis, clinical features, radiological features, and histopathology of dentigerous cyst.

Write about histopathology of dentigerous cyst.

(Synonym: follicular cyst)

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Cystic lumen

Parakeratinized epitheliallining with surfacecorrugations

Palisaded basal layer

Separation of epitheliallining from capsule

Fig. 11.2. Odontogenic keratocyst.



Defi nition: Dentigerous cyst is defi ned as a cyst that originates by the separation of the dental follicle from the crown of an unerupted tooth (dentigerous means tooth bearing).

Pathogenesis

Fluid accumulationHyperplasia of enamel

organ epithelium

• Within the enamel organ • Between the reduced enamel

epithelium and enamel• Within the reduced enamel

epithelium

Degeneration of stellate reticulum

Associated with enamel hypoplasia

Cystic degeneration

I. Intrafollicular origin

Periapical cyst in relation to deciduous toothUnderneath permanent tooth may indent the wall of the periapical cyst

II. Extrafollicular origin

Clinical featuresAge ● : 20–40 yearsGender ● : Male predilectionSite: ● Mandibular third molar regionSigns and symptoms ●

It is an asymptomatic lesion (small-sized lesions) commonly associated with ❍

unerupted tooth.Slow growing, painless swelling with cortical plates expansion is seen (large-sized ❍

lesions). On palpation ❍

Th inning of cortical plates: Crepitus-like sensation. ❒

If the overlying bone is perforated: Fluctuation ❒ . Most of the lesions are detected during routine radiological examination due to ❍

missing or impacted tooth.Sometimes pain may be present due to secondary infection. ❍

Paresthesia on the aff ected part and pathological fractures of the jaw may occur. ❍

Radiological featuresUsually, well-defi ned unilocular radiolucency associated with unerupted tooth is seen. ●

Occasionally, multilocularity is seen due to bony trabeculations. ●

Th ree radiological variants are observed (Fig. 11.3). ●

Th e central type: ❍ Th e cyst envelops the crown symmetrically.



Th e lateral type: ❍ Th e cyst envelops the crown laterally and commonly associated with partially impacted tooth. Circumferential type: ❍ Th e cyst envelops the entire tooth.

Histopathology (Fig. 11.4)It consists of nonkeratinized epithelial lining with two to four layers of fl at or cuboidal ●

cells.Th e connective tissue capsule is loosely arranged and contains considerable amount of ●

glycosaminoglycan ground substance. Nests, islands, and strands of odontogenic epithelium are often seen in the connective ●

tissue capsule.Often, mucus-producing cells are seen in epithelial lining (prosoplasia – forward dif- ●

ferentiation). Th e frequency of mucous cells increased in proportion to the age of the patients.Th e intense infl ammatory cell infi ltrate in the capsule causes localized hyperplasia or ●

discontinuity of overlying epithelium. Occasionally, bud-like thickenings of the epithelium into the fi brous capsule may be ●

seen even in the absence of infl ammation ( mural proliferations).

Complications of dentigerous cystAmeloblastoma: ● It develops either from epithelial lining or from nests of odontogenic epithelium in the wall of the cyst.

(a) (b) (c)

Fig. 11.3. Schematic diagram illustrating the manner in which the dental follicle expands to produce the radiographic appearances of (a) central, (b) lateral, and (c) circumferential variant of dentigerous cysts.

Tooth

Cystic lumen

Epithelial lining

Connective tissue capsule

Odontogenic epithelial islands

Fig. 11.4. Dentigerous cyst.



Squamous cell carcinoma: ● It develops from same two sources as described above. ● Mucoepidermoid carcinoma: It develops from epithelial lining containing mucous cells or cells with this potential transformation.

Diff erential diagnosisAdenomatoid odontogenic tumor ●

Ameloblastoma (unicystic) ●

Odontogenic keratocyst ●

Prognosis and predictive factors Smaller lesions: Enucleation ●

Larger lesions: Marsupialization or surgical resection ●

Recurrence is relatively uncommon ●

ERUPTION CYST

Write about eruption cyst.

(Synonym: eruption hematoma)

Defi nition: Eruption cyst is defi ned as an odontogenic cyst with the histologic features of a dentigerous cyst that surrounds a tooth crown that has erupted through bone but not soft tissue and is clinically visible as a soft fl uctuant mass on the alveolar ridges.

PathogenesisIt is similar to that of the dentigerous cyst, but the tooth in the case of the eruption cyst ●

is impeded in the soft tissues of the gingiva rather than in the bone.Few studies reported that the administration of cyclosporine may lead to the develop- ●

ment of eruption cysts.

Clinical featuresAge ● : 10–20 yearsGender ● : Male predilectionLocation ● : Deciduous mandibular central incisors and permanent fi rst molars regionSigns and symptoms ●

Usually bilateral, symmetrical, and concurrent smooth swellings. ❍

Over the erupting tooth, it may be either the color of normal gingiva or blue hue. ❍

It is usually painless unless infected and is soft and fl uctuant. ❍

Usually surface trauma may result in a considerable amount of blood in the cystic ❍

fl uid, which imparts a blue to purple-brown color – eruption hematoma.Transillu ❍ mination is a useful diagnostic aid.

Radiological feature: Th e cyst may show a soft-tissue shadow, but there will be no bone involvement.

HistopathologyTh e superfi cial aspect is covered by the parakeratinized stratifi ed squamous epithelium ●

(gingiva).Superfi cial epithelium is separated from the cyst by a strip of dense connective tissue of ●

varying thickness which usually shows a mild chronic infl ammatory cell infi ltrate.

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Frequent exposure to masticatory trauma – infl ammatory infi ltrate invariably increases ●

towards the cyst lining.Th e gingival connective tissue is acellular, densely collagenous, and shows eosinophilic ●

hue. Th e follicular connective tissue capsule is densely cellular, less collagenous, and shows baso- ●

philic hue (due to high content of sulfated glycosaminoglycans in the ground substance).In noninfl amed areas, the cystic epithelial lining shows two to four cell layers of fl at or ●

cuboidal cells, whereas in infl amed areas epithelial lining shows hyperplasia and may form characteristic arcades.

Diff erential diagnosisGingival cyst ●


Residual cyst ●

Prognosis and predictive factors: Treatment may not be required because the cyst usually ruptures spontaneously, permitting tooth to erupt. If not, simple surgical excision of the cyst is needed.

GINGIVAL CYST AND MIDPALATAL RAPHE CYST OF INFANTS

Write about pathogenesis, clinical features, and histopathology of gingival cyst of infants.

Explain midpalatal raphe cyst of infants.

What are Bohn’s nodules and Epstein’s pearls?

(Synonym: dental lamina cyst of newborn)

Defi nition: Gingival cyst of infants is small, superfi cial, keratin-fi lled cysts that are found on the alveolar mucosa of infants that resolve without treatment.Note: Th e gingival and the midpalatal raphe cysts of infants are conveniently discussed together because they have similar clinical features, although the former lesion is of odontogenic origin and the latter lesion is a developmental origin.Pathogenesis

Gingival cysts of infants

Cell rests of Serre

Proliferate and keratinize (10 weeks IU)

Gingival cyst of infants

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Midpalatal raphe cyst of infantsAbortive glandular diff erentiation leading to cyst formation: ● Bohn’s nodules. Epithelial inclusions at the line of palatine shelves fusion: ● Epstein’s pearls.

Clinical featuresAge ● : InfantsGender ● : Females predilectionLocation ● : Maxillary alveolus regionSigns and symptoms ●

Th e lesions are usually multiple, small, asymptomatic whitish or cream colored pap- ❍

ules on the mucosa overlying the alveolar processes of neonates. Th e cysts are round or ovoid in shape and may have a smooth or an undulating ❍

outline measuring about 2–3 mm in diameter.Most of them undergo involution and disappear or rupture through the surface ❍

epithelium and exfoliate.Bohn’s nodules or Epstein’s pearls: Bohn’s nodules are scattered over the hard pal- ❍

ate, often near the soft palate junction. Epstein’s pearls occur along the midpalatine raphe of the hard palate.

Note: Cysts are absent in the soft palate due to consolidation of the soft palate and uvula takes place not by fusion instead by subepithelial mesenchymal merging of bilateral primordia.

Radiological features: Th e cyst may show soft-tissue shadow or saucerization (superfi cial erosion) of the underlying bone.

HistopathologyCystic cavity fi lls keratin, usually in concentric laminations. ●

A thin parakeratotic stratifi ed squamous epithelial lining with fl at basal cells are seen. ●

Epithelial-lined clefts may develop between the cyst and surface oral epithelium. ●

Sometimes, oral epithelium may be atrophic due to cystic pressure. ●

Midpalatine raphe cysts show similar histological appearance as described above. ●

Diff erential diagnosisEruption cyst ●

Epulis (congenital) ●

Prognosis and predictive factors Treatment may not be required because the cyst usually ruptures spontaneously upon ●

resultant contact with the oral mucosal surface.Th e lesions are rarely seen after 3 months of age. ●

LATERAL PERIODONTAL CYST

Discuss pathogenesis, clinical features, radiological features, and histopathology of lateral periodontal cyst.

Defi nition: A slow growing, nonexpansile developmental odontogenic cyst derived from one or more rests of the dental lamina, comprising of embryogenic lining of one to three

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cuboidal cells and distinctive focal thickenings (plaque). Th e multicystic variant of lateral periodontal cyst is known as botryoid odontogenic cyst.

Pathogenesis: Th e possible sources of cyst formation are as follows:

Reduced enamel epithelium

Dentigerous cysts associated with vertically impacted tooth

Tooth erupts normally

The cyst comes to lie in the lateral aspect of the root – Lateral periodontal cyst

Remnants of dental lamina

Cystic change in a single dental lamina rest

Unicystic lesions(Postfunctional rests: limited growth potential)

Concomitant changes occur in several adjacent cell rests

Polycystic lesions(Postfunctional rests: marked growth potential)

Cell rests of Malassez: It is present in the periodontium and its position is conducive.

Clinical featuresAge ● : 21–81 yearsGender ● : No sex predilectionLocation ● : Mandibular premolar areaSigns and symptoms ●

It is an asymptomatic lesion associated with vital tooth that may be usually detected ●

during routine radiographic examination. Usually, it occurs on facial aspect of gingiva, which shows normal or bluish in color. ●

In some cases, pain may be present or may elicit tenderness on palpation. ●

On palpation, some swellings may depict as springy with ● egg shell crackling (thinning of cortical plate) or gelatinous feel (cortical plate perforation).

Radiological featuresUsually it appears as a well-circumscribed, unilocular, round or oval-shaped radiolu- ●

cent lesion on lateral aspect of the root.Most of the lesions are less than 1 cm in diameter except the botryoid variant, which is ●

a larger and multilocular lesion extend up to or beyond periapical region also.

HistopathologyEpithelial lining shows one to fi ve layers thickness of squamous or cuboidal cells. ●

Abundant glycogen-rich clear cells are frequently seen in the epithelial lining. ●



Usually, it shows localized plaques or thickenings of the epithelial lining extending into ●

surrounding capsule. It may also produce mural bulges protruding into lumen.Th e epithelium-connective tissue interface will be tenacious and may peel off easily. ●

Small epithelial nests or follicles are seen in the fi brous capsule. Th ese nests may en- ●

large and be the source for multiple microcysts formation – botryoid odontogenic cyst (botryoid means cluster of grapes). Few cysts were lined by hyperplastic stratifi ed squamous epithelium with verrucous ●

projections and shedding keratin into the lumen – verrucous odontogenic cyst.

Diff erential diagnosis Gingival cyst of adults ●

Radicular cyst ●

Lateral periodontal abscess ●

Prognosis and predictive factors Conservative enucleation without damage to the adjacent teeth is recommended. ●

Recurrence is unusual, although it has been reported with the botryoid variant, pre- ●

sumably because of its polycystic nature.

GINGIVAL CYST OF ADULTS

Write about pathogenesis, clinical features, radiological features and histopa-thology of gingival cyst of adults.

Defi nition: A small developmental odontogenic cyst of the gingival soft tissue derived from the rests of the dental lamina, containing a lining of embryonic epithelium of cuboidal cells and distinctive focal thickenings similar to the lateral periodontal cyst. Gingival cyst of adults represents the extraosseous counterpart of the intraosseous lateral periodontal cyst.

Pathogenesis (Fig. 11.5) Th e possible sources of cyst formation are as follows:

Remnants of odontogenic epithelium. ●

Traumatic implantation of surface epithelium. ●

Cystic degeneration of deep projections of gingival epithelium. ●

Heterotopic glandular elements. ●

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Bone Bone

(a) (b)

Fig. 11.5. Schematic diagram illustrating the pathogenesis of lateral periodontal cyst (a) and gingival cyst of adults (b) (C – cyst).



Th e gingival cyst of adults and the lateral periodontal cyst may arise from the same source. Buchner and Hansen in 1979 postulated that the lateral periodontal cyst is formed from the reduced enamel epithelium by dilatation of the follicle before eruption of the tooth, whereas the gingival cyst of adults is derived from reduced enamel epithelium after eruption of the tooth.

Origin of these cysts from postfunctional epithelium (reduced enamel epithelium) would help to explain the nonaggressive nature of the gingival cyst of adults and the lateral periodontal cyst.

Clinical featuresAge ● : 23–70 yearsGender ● : Female predilectionLocation ● : Premolar – canine region of the mandible.Signs and symptoms ●

It occurs as a soft, well-circumscribed, round to oval shaped, slow growing, pain- ❍

less swelling, and usually occurs on facial aspect of attached gingiva or interdental papilla.Th e adjacent teeth will be vital. ❍

Usually, it shows normal or bluish in color. ❍

Radiological featuresUsually, no radiological changes are seen. ●

Sometimes saucerization of the underlying bone may be seen. ●

HistopathologyEpithelial lining may be ●

Th in and composed of one to three layers of fl at to cuboidal cells (or) ❍

Th ick, stratifi ed, squamous epithelium without rete ridges. Sometimes numerous ❍

clear cells are seen (or) Atrophic and only ghost-like outline remains. ❍

Th e epithelium-connective tissue interface is tenuous and can be peeled off in many ●

areas.Th e fi brous capsule is usually uninfl amed except in the region close to the junctional ●

epithelium, where a dense chronic infl ammatory infi ltrate may be seen. Layers of keratin may be present in the cystic lumen. ●

Th e lesion is usually unicystic, but multicystic variants are also encountered. ●

Diff erential diagnosisLateral periodontal cyst ●

Pyogenic granuloma ●

Radicular cyst ●

Prognosis and predictive factors Surgical excision ●

Prognosis is excellent ●



CALCIFYING ODONTOGENIC CYST

Classify and write about pathogenesis, clinical features, radiological features, and histopathology of calcifying odontogenic cyst.

Describe histopathology of calcifying odontogenic cyst.

What are ghost cells?

(Synonyms: Gorlin cyst, calcifying ghost cell odontogenic cyst)Th e calcifying odontogenic cyst ( COC) was fi rst described by Gorlin, 1962, hence the eponym Gorlin cyst.

Defi nition: A cystic lesion in which the epithelial lining shows a well-defi ned basal layer of columnar cells, an overlying layer that is often many cells thick and that may resemble stellate reticulum, and masses of ghost epithelial cell that may be in the epithelial lining or in the fi brous capsule. Th e ghost epithelial cells may become calcifi ed. Dysplastic dentin may be laid down adjacent to the basal layer of the epithelium and in some instances the cyst is associated with an area of more extensive dental hard tissue formation resembling that of a complex or compound odontoma.

Classifi cation: Based on the biological behavior, Praetorius (2006) classifi ed COC into three groups – cysts, benign tumors, and malignant tumors. Th e term COC should be used specifi cally to designate the isolated unicystic lesions without any associated tumors or hamartomas.Group 1 Simple cyst: Calcifying odontogenic cyst (COC)Group 2 Cysts associated with odontogenic hamartomas or benign neoplasms: Calcifying cystic odontogenic tumors (CCOT). Th e following combinations

have been published:CCOT associated with an odontoma ●

CCOT associated with adenomatoid odontogenic tumor ●

CCOT associated with ameloblastoma ●

CCOT associated with ameloblastic fi broma ●

CCOT associated with ameloblastic fi bro-odontoma ●

CCOT associated with odontoameloblastoma ●

CCOT associated with odontogenic myxofi broma ●

Group 3 Solid benign odontogenic neoplasms with similar cell morphology to that in the COC with dentinoid formation: Dentinogenic ghost cell tumor

Group 4 Malignant odontogenic neoplasms with features similar to those of the dentinogenic ghost cell tumor: Ghost cell odontogenic carcinoma

PathogenesisCOC may arise as ● de novo lesion. It may develop from reduced enamel epithelium or remnants of odontogenic epithe- ●

lium in the follicle, gingival tissue, or bone.

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COC may develop has a secondary phenomena in pre-existing odontogenic tumors. ●

Praetorius (1981) believes that the dentinogenic ghost cell tumor is a ● de novo neoplasm, but the COC plus benign neoplasm or hamartoma is a cyst from the beginning.

Clinical featuresIt occurs in two forms: ●

Central/intraosseous variant ❍

Peripheral/extraosseous variant ❍

Age ● : 20–60 yearsGender ● : No sex predilectionLocation ● : Canine to fi rst molar region of both mandible and maxilla.Signs and symptoms ●

Th e intraosseous variant often presents as a painless slow-growing swelling, which ❍

may produce extensive bony hard expansion. Occasionally, it may perforate the cortical plate and extend into overlying soft tis- ❍

sues. In few cases, displacement of the teeth can be seen. ❍

Extraosseous lesions tend to be pink to red in color and appear as a circumscribed ❍

elevated mass on gingiva.

Radiological featuresIntraosseous lesions show well-defi ned unilocular or multilocular radiolucent areas ●

containing radiopaque masses of varying sizes (snow-driven appearance). Frequently, displacement of teeth and resorption of the roots are seen. ●

Th e extraosseous lesions show saucerization of the underlying bone. ●

Histopathology Th e epithelial lining shows palisaded basal layer consisting of columnar or cuboidal ●

cells with hyperchromatic nuclei polarized away from the basement membrane. Th e suprabasal layer consists of stellate reticulum-like cells.Th e presence of ghost cells in the epithelial lying is the most characteristic feature. ●

❍ Ghost cells appear as well-defi ned eosinophilic masses and/or basophilic nuclear remnants in it.Th e ghost cells may represent abnormal keratinization that have an affi nity for cal- ❍

cifi cation or the product of coagulative necrosis of odontogenic epithelium or dys-trophic calcifi cation, or foreign body reaction with the formation of multinucleate giant cells.

Often, subepithelial dentinoid material is seen. ●

Budding from the basal layer of epithelial lying into the connective tissue capsule or ●

epithelial proliferations into the lumen are frequently seen.

Diff erential diagnosisCalcifying epithelial odontogenic tumor ●

Adenomatoid odontogenic tumor ●

Ameloblastoma ●



Prognosis and predictive factors Isolated COC: Recurrence is less common and it can be treated by simple enucleation. ●

COC associated with tumor: Recurrence is common and surgical resection is required. ●

NASOPALATINE DUCT CYST

Describe nasopalatine duct cyst.

(Synonym: incisive canal cyst)

Defi nition: Nasopalatine duct cyst is a relatively common nonodontogenic intraosseous, cystic lesion arising within the nasopalatine duct or the incisive canal.

PathogenesisTh e exact mechanism is unknown. ●

Th e nasopalatine duct cyst will be derived from embryonic epithelial residues in the ●

nasopalatine canal or epithelial cells included in the lines of fusion of embryonic facial processes. Th e vomeronasal organs of Jacobson are sometimes mentioned as a possible source of ●

cysts in the incisive canal but this is most unlikely.

Clinical featuresAge ● : 30–60 yearsGender ● : Male predilectionLocation ● : Anterior region of the mid palateSigns and symptoms ●

Th e most common symptom is the swelling, which usually occurs in the anterior ❍

region of the mid palate or in the midline on the labial aspect of the alveolar ridge or in some cases through and through fl uctuation may be elicited between the labial and palatal swellings. Th e swelling may be associated with pain (due to pressure on the nasopalatine ❍

nerves) or discharge. Sometimes discharge or pain will be the only symptom elicited. Various combinations of swelling, discharge, and pain may also occur in few cases. Th e discharge may be mucoid – salty taste or purulent – foul taste. ❍

Th ere may be a history of recurrent swellings that periodically discharge and then ❍

regresses. Th e adjacent teeth will be vital. ❍

Radiological featuresUsually, it appear as a ● heart-shaped radiolucent area between maxillary central inci-sors, this appearance is either because they notched by the nasal septum during their expansion or the nasal spine may superimpose on the radiolucent area or if there are bilateral cysts. Th e incisor roots may diverge, but root resorption is rare. ●

Th e adjacent teeth shows intact lamina dura around the roots (indicates vital pulp). ●

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Sometimes, the cyst may be confused with the incisive foramen. In such cases, a second ●

radiograph should be taken at a diff erent angulation. Th e average size of nasopalatine duct cyst is 1–2.5 cm in diameter, whereas incisive fo- ●

ramen will be 6 mm in diameter. Th erefore if the suspected lesion is measuring about 6 mm or less without clinical symptoms, the diagnosis should be incisive foramen rather than a cyst.

HistopathologyTh e epithelial lining is extremely variable. Stratifi ed squamous, pseudostratifi ed ciliated ●

columnar, cuboidal, columnar, or primitive fl at epithelium may be seen, individually or in combination.Goblet cells may be found frequently in epithelial lining. ●

Respiratory epithelium probably originates from nasopalatine duct adjacent to the na- ●

sal cavity, whereas those lined by stratifi ed squamous epithelium may develop from the lower portion of the duct.A valuable diagnostic feature of nasopalatine duct cysts is the presence of nerves and ●

blood vessels with small foci of mucous glands in the fi brous capsule.

Diff erential diagnosisNasopalatine duct ●

Radicular cyst ●


Prognosis and predictive factors Surgical enucleation ●

Recurrence is rare ●

Note: In recent years, the existence of median palatine cyst, median alveolar cyst, and globulomaxillary cyst as separate entities has been questioned and they were excluded from the 1992 WHO classifi cation of epithelial jaw cysts. Previously, it had been thought that these cysts developed from epithelium entrapped in the process of fusion of embryonic processes, but now it is believed that they represent posterior extension of an incisive canal cyst in the case of median palatine cyst and anterior extension in the case of median alveolar cyst, and odontogenic keratocyst in the case of the globulomaxillary cysts. Sometimes, median alveolar cyst may also be a keratocyst derived from dental lamina in the midline of the maxilla.

NASOLABIAL CYST

Describe nasolabial cyst.

(Synonyms: nasoalveolar cyst, klestadt cyst)

Defi nition: Nasolabial cyst is a rare developmental soft tissue cyst that occurs in the upper lip lateral to the midline deep into the nasolabial fold.

PathogenesisIt may arise from epithelium enclaved at the site of fusion of the globular, lateral nasal, ●

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and maxillary processes. Th is concept, however, is not tenable as the embryological basis for it has been seriously disputed. Th ey may also developed from the lower anterior part of the nasolacrimal duct. ●

Clinical featuresAge ● : 12–75 yearsGender ● : Female predilectionLocation ● : It occurs outside the bone in the nasolabial folds below the alae nasi.Signs and symptoms ●

Th e most frequent symptom will be the swelling. Sometimes the patients com- ❍

plained of pain and diffi culty in nasal breathing, but pain and discharge is generally present among infected cysts. Th e cysts grow slowly, producing a swelling of the lip and form a bulge in the labial ❍

sulcus. Th ey fi ll out the nasolabial fold and often lift the alae nasi, distort the nostril, and produce a swelling in the fl oor of the nose. Th e cysts are fl uctuant and on bimanual palpation, fl uctuation may be elicited be- ❍

tween the swelling on the fl oor of the nose and labial sulcus.

Radiological features: Radiolucent depression on the labial surface of the anterior maxilla can be detected in a tangential view (PA view) radiograph.

HistopathologyUsually cyst is lined by nonciliated pseudostratifi ed columnar epithelium, but in some ●

cases, epithelial lining may consists of one to two layers of cuboidal or fl at squamous cells. Numerous goblet cells are frequently seen in epithelial lining. ●

Th e fi brous capsule is relatively acellular and is either loosely or densely collagenous. ●

Mucous glands are commonly seen in the fi brous capsule. ●

Diff erential diagnosisNasopalatine duct cyst ●

Lateral periodontal cyst/abscess ●

Gingival abscess ●

Prognosis and predictive factors Complete surgical excision of the cyst is recommended. ●

Recurrence is rare. ●

RADICULAR CYST AND RESIDUAL CYST

Discuss pathogenesis, clinical features, radiological features, and histopathology of radicular cyst.

Describe the pathogenesis of radicular cyst.

Explain the histopathology of radicular cyst.

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What are Rushton bodies?

Write a note on cholesterol clefts.

Elucidate the features of residual cyst.(Synonyms: periapical cyst, apical periodontal cyst)

Defi nition: Radicular cysts are the most common infl ammatory cysts and arise from the epithelial residues in the periodontal ligament as a result of periapical periodontitis follow-ing death and necrosis of the pulp (nonvital tooth). Residual cyst is a radicular cyst that is retained in the jaws after the removal of off ending nonvital tooth. Infl ammatory periodontal cyst or infl ammatory collateral cyst is an infl ammatory cyst that occurs towards the lateral aspect of a root as a consequence of an infl ammatory process in a periodontal pocket. Paradental cyst is an infl ammatory cyst occurring on the lateral aspects of the roots of partially erupted mandibular third molars with an associated history of pericoro-nitis. Mandibular infected buccal cyst is an infl ammatory cyst occurring on the buccal surfaces of the mandibular molars in young children.

Pathogenesis: Th e formation of radicular cyst occurs in three phases: Th e phase of initiation ●

Th e phase of cyst formation ●

Th e phase of cyst enlargement ●

Th e phase of initiationTh e epithelial linings of these cysts are derived from the epithelial cell rests of Malassez in the periodontal ligament, which lie near periapical granuloma associated with nonvital teeth. Th e epithelial cell rests are initiated to proliferate as follows:

Infected/dead pulpal products

Evokes acute infl ammation

Changes in connective tissue

↓O2, ↑CO2, ↓pH

Activated T-cells

Lymphokines

Bacterial antigens

Ag-Ab Complex

Epithelial Cell Rests of Malassez

Proliferation

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Th e phase of cyst formation

Lack of nutrition/ autolysis of central cells

Proliferation of cells around preformed cavity

Stimulus

Fusion of microcystsCentral cells acquire antigenic properties

Central cells are targeted and lysed

Cell Rests

Proliferation

Cyst

Th e phase of cyst enlargement

Increased osmotic pressure in cystic fl uid

• Epithelial and infl ammatory cells degradation products

• Glycosaminoglycans• Plasma proteins and

hyaluronic acid

Infl ammation

ProstaglandinsEpithelial

proliferation

Increased collagenase activity

Absence of lymphatic drainage

Increased hydrostatic pressure in cystic fl uid

Cyst Expansion

Cyst

Clinical featuresAge ● : 40–50 yearsGender ● : No gender predilectionLocation ● : Maxillary anterior regionSigns and symptoms ●



Usually, radicular cysts are asymptomatic and are discovered when periapical radio- ❍

graphs are taken due to tooth discoloration (nonvital tooth). Th e bony hard, slow-growing swelling is often seen. As the cyst increases in size, ❍

the covering bone becomes very thin despite subperiosteal bone deposition occurs, which exhibits springiness or egg shell crackling. If the cyst has completely eroded the bone, the lesion will be fl uctuant.Pain will be elicited due to secondary infection. Occasionally, a sinus may lead from ❍

the cyst cavity to the oral mucosa.Involved tooth will be nonvital. Vitality test elicit negative response. ❍

Radicular cysts occur rarely among deciduous teeth due to following reasons: ❍

Pulpal and periapical infections in deciduous teeth tend to drain more readily ❒

than those of permanent teeth. Th e antigenic stimuli that evoke the changes leading to the formation of radicular ❒

cysts may be diff erent among deciduous teeth. Pulpal fl oor of the deciduous teeth contains numerous accessory canals which ❒

intend to cause furcation involvement rather than periapical lesions.

Radiological featuresUsually, the lesions measuring 10–14 mm are granulomas and the lesions measuring ●

15 mm or more are cysts.Classically, radicular cysts appear well-defi ned round or ovoid-shaped radiolucency ●

with a thin sclerotic border, which indicates a reaction of the bone to the slowly ex-panding lesion.In infected or rapidly enlarging cysts, the sclerotic border around the cysts may not be ●

observed. Loss of continuity of lamina dura of the involved tooth is frequently seen. ●

Root resorption may be seen in few lesions. ●

Histopathology Th e cystic fl uid contents are usually brown due to breakdown of blood and when cho- ●

lesterol crystals are present they impart a shimmering gold or straw color.Usually they are lined by stratifi ed squamous epithelium. Th ese linings may be discon- ●

tinuous in part and range in thickness from 1 to 50 cell layers. In early cysts, the epithelial lining may be proliferative and show arcading pattern with ●

an intense infl ammatory process but as the cyst enlarges the lining becomes quiescent and fairly regular with a certain degree of diff erentiation to resemble a simple stratifi ed squamous epithelium. Metaplastic changes in the form of mucous cells or ciliated cells are frequently seen. ●

Rushton’s hyaline bodies are frequently found in the epithelial lining. Th ey are linear, ●

curved, or hairpin-shaped structures and sometimes they are concentrically laminated also. Th ese may be originated from

Secretory product of odontogenic epithelial cells. ❍

Hematogenous origin – thrombi shrank centrifugally and underwent splitting, or ❍

they may calcify.Degenerating red blood cells. ❍



Th e cholesterol crystals are usually deposited in the fi brous capsule. Th ey behave as ●

foreign bodies and excite a foreign body giant cell reaction. In histological sections, the cholesterol crystals are dissolved out and clefts surrounded by dense aggregations of multinucleate giant cells are seen. Th e main source of cholesterol crystals are:

Disintegrating red blood cells. ❍

Degeneration and disintegration of lymphocytes and plasma cells. ❍

β ❍ -lipoproteins in the plasma pass through the fragile thin-walled blood vessels in the infl amed portions of cyst wall.

Varying intensities of acute and chronic infl ammatory cell infi ltrate are present in con- ●

nective tissue capsule. Calcifi cations are frequently present in a cyst of longer time. ●

Simon (1980) showed two types of radicular cyst. ●

True radicular cyst ❍ , which contains a closed cavity entirely lined by epithelium.Periapical pocket cyst ❍ ( bay cyst) in which the epithelium is attached to the margins of apical foramen in such a way that the cyst lumen is open to the aff ected root canal. Th us, it is expected that the pocket cyst would heal after treatment or tooth extraction, while the true cyst is self-sustaining and may persist even in the absence of etiology.

Diff erential diagnosisPeriapical granuloma ●

Central giant cell granuloma ●

Periapical abscess ●

Prognosis and predictive factorsSmall cysts ● : Root canal treatment of the aff ected teeth and apical curettage.Large cysts ● : Surgical enucleation or marsupialization.

Residual cyst is the radicular cyst that is retained in the jaws after the removal of off ending nonvital tooth. It may be asymptomatic or symptomatic residual cysts.

Asymptomatic cysts ● , they are usually seen in the mandibular premolar region and there was a direct relationship between the age of the cyst and the radiological and histologi-cal evidence of mineralization. Th ere was an overall reduction in epithelial thickness with cyst age and all cysts showed minimal chronic infl ammatory changes. Th ese re-sidual cysts are slowly resolving lesions. Symptomatic cysts ● may produce pain or swelling, or both. Th e mean cyst size was larger than that of asymptomatic cysts and has a negative correlation with cyst age. It oc-curs commonly in the mandibular premolar region. Cortication of the cyst wall is radiographically signifi cant. Acute and chronic infl ammatory cell infi ltration showed invariable intensity.

SOLITARY BONE CYST

Give a brief account of solitary bone cyst. (Synonyms: traumatic bone cyst, hemorrhagic bone cyst, unicameral bone cyst)

Defi nition: Th e simple bone cyst is an empty or fl uid containing cavity within the bone that is devoid of an epithelial lining.

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PathogenesisTraumatic theory ●

Trauma to a bone

Intramedullary hemorrhage

Failure of early organization of the hematoma

Liquefaction of the clot

Traumatic cyst

Cystic degeneration of primary bone tumors. ●

A result of faulty calcium metabolism such as parathyroid disease. ●

Ischemic necrosis of fatty bone marrow. ●

Clinical featuresAge ● : 10–60 yearsGender ● : No gender predilectionLocation ● : Posterior region of the mandibleSigns and symptoms ●

Usually, asymptomatic lesion. ❍

Swelling may be a presenting symptom. Sometimes patient may complain of labial ❍

paresthesia.Most of the patients give a history of signifi cant trauma in the involved area. ❍

All the related teeth will be vital. ❍

Radiological featuresIt appears as a unilocular or multilocular radiolucent area with irregular but defi nite ●

border and slight cortication.Cone-shaped morphology ● : One lateral margin of the lesion formed an angular inter-face with normal bone with two planes converging at a 45° angle to produce a sharp cone eff ect. Most often, the cone pointed anteriorly towards the midline.Th e lamina dura may or may not be lost and occasionally root resorption is seen. ●

HistopathologyOn surgical exposure, the cyst cavity is found to be empty. In some cases, blood or ●

serosanguineous or serous fl uid may be present. Th e cyst will be lined by a thin band of vascular fi brous connective tissue or demon- ●

strate a thickened myxofi bromatous proliferation that often intermixed with trabeculae of cellular or reactive bone.



Epithelial lining will be absent. ●

Hemorrhage and hemosiderin pigment are usually present with scattered multinucle- ●

ated giant cells.Long-standing cysts show more densely fi brous capsule. ●

Diff erential diagnosisAneurysmal bone cyst ●


Ameloblastoma ●

Prognosis and predictive factorsTh e treatment is done by surgical exploration of the cyst, which helps in causing further ●

hemorrhage in the area with subsequent healing. Some lesions may resolve spontaneously. ●

ANEURYSMAL BONE CYST

Discuss pathogenesis, clinical features, radiological features, and histopathology of aneurysmal bone cyst.

Describe the pathogenesis of aneurysmal bone cyst.(Synonyms: ossifying hematomas, osteitis fi brosa cystic)

Defi nition: Aneurysmal bone cyst ( ABC) is a benign intraosseous lesion characterized by blood-fi lled spaces of varying sizes associated with a fi broblastic tissue containing multi-nucleated giant cells, osteoid, and woven bone (WHO, 2005).

PathogenesisLiechtenstein (1942) proposed that ●

Persistent local alteration in hemodynamics

Increased venous pressure

Development of a dilated and engorged vascular bed in the transformed bone area

Resorption of bone (so, giant cells is seed) and this is replaced by connective tissue, osteoid and new bone

Biesecker (1970) reported that aneurysmal bone cysts accompanying with benign pri- ●

mary lesion of bone.

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Primary lesion of bone initiates ossifi cation and arteriovenous fi stula

Altered hemodynamic forces

ABC–Secondary reactive lesion of bone

Levy (1975) reported that ABC occurs secondary to or in association with osseous ●

lesions. ABC is most commonly associated with solitary or unicameral bone cyst, os-teoclastoma, osteosarcoma, nonosteogenic fi broma, benign osteoblastoma, hemangio-endothelioma, and hemangioma of bone.Struthers and Shear (1984)● hypothesized that ABC formed as a secondary phenom-enon, which may develop by breakdown of a pre-existing lesion in bone. Th e initiating change in primary lesion appears to be the microcyst formation.Four phases of pathogenesis are recognized as follows:●

Osteolytic initial phase.❍

Active growth phase❍ includes rapid destruction of bone and subperiosteal blow out pattern.Mature stage: It also known as stage of stabilization, which is manifested by the ❍

formation of distinct peripheral bony shell and internal bony septa that produce the classic soap-bubble appearance.Healing phase shows progressive calcifi cation and ossi fi cation of the cyst.❍

Clinical featuresIt occurs in two forms●

Primary ABC: No pre-existing bone lesion is seen. ❍

Secondary ABC: Well-recognized pre-existing bone lesion will be present. ❍

Age ● : < 20 yearsGender ● : Female predilectionLocation ● : Mandible, long bonesSigns and symptoms ●

Th e lesions are usually tender, particularly upon motion and this soreness may limit ❍

movement of the aff ected bone. Swelling over the area of bone involvement is common.❍

Paresthesia, compressibility, crepitus, malocclusion, mobility, and resorption of in- ❍

volved teeth are common.A characteristic gross feature at the time of operation – upon entering into the le- ❍

sion, excessive bleeding is encountered, which appears as a blood welling up from the tissue. Tissue resembles as a blood-soaked sponge with large pores.

Radiological features: Lesion may appear as an unilocular, honeycomb, or soap-bubble radiolucent area that causes expansion, perforation, or even destruction of bone.



HistopathologyIt consists of a fi brous connective tissue stroma containing many cavernous or sinu- ●

soidal blood-fi lled spaces. Usually, these blood-fi lled spaces are not lined by endothe-lium.Numerous young fi broblasts and patchy distribution of multinucleated giant cells were ●

seen in the connective tissue stroma. Commonly, varying amount of hemosiderin pigments and osteoid formation is seen. ●

Diff erential diagnosisFibrous dysplasia ●

Intraosseous hemangioma ●

Traumatic bone cyst ●

Prognosis and predictive factors Surgical curettage or excision is the treatment of choice. ●

Recurrence is rare. ●

CYSTS OF THE SALIVARY GLANDS

Discuss pathogenesis, clinical features, and histopathology of cysts of the salivary glands.

Write about pathogenesis, clinical features, and histopathology of mucocele.

What is mucous extravasation cyst.

Describe mucous retention cyst.

Discuss about ranula.

Cystic lesions developing from the salivary glands are commonly known as mucocele. Th ese cysts will commonly develop in relation to the minor salivary glands. Mucocele includes both mucous extravasation cysts and mucous retention cysts.

Mucous extravasation cyst: ● Lesions in which mucin is extravasated into the connective tissue and it is devoid of epithelial lining (pseudocyst). Mucous retention cyst: ● Lesions in which mucin is retained in the dilated salivary excre-tory duct and it is lined by epithelium (true cyst).

Pathogenesis (Fig. 11.6)Pathogenesis of mucous extravasation cyst and mucous retention cyst is as follows:

Clinical featuresAge ● : 10–60 yearsGender ● : No gender predilectionLocation ● : Lower lipSigns and symptoms ●

Usually, painless, round or oval shaped, recurrent swelling occurs on lower lip. ❍

Th e swelling may develop suddenly at mealtimes and many drain spontaneously at ❍

intervals.

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Some patients are able to relate the development of cyst due to trauma. ❍

Usually, mucocele will be 1–2 mm in diameter but sometimes it may reach up to ❍

10 mm in diameter. Th e superfi cial lesions are blue and fl uctuant while the deeper lesions have the color ❍

of normal mucosa.

HistopathologyMicroscopically, three distinct morphological patterns are seen. Th e fi rst two patterns repre- ●

sent mucous retention cysts and the third pattern represent mucous extravasation cyst. ❍ Mucous retention cysts (well-defi ned cysts) comprised of two groups:

Th e periphery of the lesion consists of granulation tissue or condensed fi brous ❒

tissue or both and was infi ltrated by vacuolated macrophages, lymphocytes, and polymorphonuclear leucocytes. One or more dilated ducts may be present and sometimes a breach may be seen in a duct. Th e cysts may be partially or completely lined by epithelium. It may consist of ❒

one or two layers of fl attened cells, cuboidal cells, stratifi ed squamous epithelium or pseudostratifi ed columnar epithelium.

❍ Mucous extravasation cysts (poorly defi ned cysts) consist of poorly defi ned pools containing eosinophilic mucinous material with numerous vacuolated macrophages – mucinophages. Usually, these cysts will be small in size but some lesions may ex-tend widely in the connective tissue (Fig. 11.7).

Diff erential diagnosis: Salivary gland tumors like adenoid cystic carcinoma, lipoma, and fi broma.

Prognosis and predictive factorsMost of the lesions are chronic in nature and local surgical excision will be necessary. ●

Few mucoceles are short-lived lesions that rupture and heal by themselves. ●

To minimize the risk of recurrence, the surgeon should remove adjacent minor salivary ●

glands also.

Mucous extravasation cyst Mucous retention cyst

Sialolith

Intraductalmucin

Trauma

Freemucin

Epithelium

Connectivetissue

Minorsalivarygland

Fig. 11.6. Pathogenesis of mucocele: mucous extravasation cyst (left) showing free mucin in the connective tissue because of ductal damage by a trauma and mucous retention cyst (right) showing mucin retained in the salivary excretory duct because of blockage by a sialolith.



Ranula

Defi nition: Th e ranula is a form of mucocele but larger in size, which specifi cally occurs in the fl oor of the mouth in association with the ducts of the submaxillary or sublingual gland. Ranula means frog’s belly.

PathogenesisSialolith formation. ●

Duct compression due to trauma or from a growing tumor in the vicinity. ●

Atresia (absence of the duct). ●

Scar or stricture formation to the duct (postsurgical complication). ●

Clinical featuresAge ● : 20–40 yearsGender ● : No gender predilectionLocation ● : Floor of the mouthSigns and symptoms ●

It usually appears as a dome-shaped, soft, fl uctuant, unilateral swelling in the fl oor ❍

of the mouth.Th e lesion is generally larger in size, which fi lls fl oor of the mouth and deviates the ❍

tongue.Usually ranula appears bluish translucent appearance but deeper lesions may be ❍

normal in color.Plunging or cervical ranula: An unusual variant occurs when the spilled mucin dis- ❍

sects through the mylohyoid muscle and produces swelling within the neck. Some ranulas rupture spontaneously and release mucin content into the mouth. ❍

Radiological featuresNot signifi cant. ●

Sialolith can be elicited in occlusal radiograph. ●

Surface epithelium

Connective tissue

Minor salivary glands

Mucin pooled area withmucinophages andinflammatory cells

Fig. 11.7. Mucous extravasation cyst.



HistopathologyIt appears similar to the smaller mucous retention cyst, which is surrounded by a fi - ●

brous connective tissue wall or granulation tissue.Multiple foamy histiocytes are often seen in the granulation tissue capsule. ●

Diff erential diagnosisDermoid cyst ●

Benign lymphoepithelial cyst ●

Prognosis and predictive factorsTh e etiological factor has to be removed to eliminate the possibility of further recurrence. In case of repeated recurrences, the involved gland has to be excised.

DEVELOPMENTAL CYSTS OF THE HEAD AND NECK

Explain thyroglossal duct cyst.

Describe dermoid cyst and epidermoid cyst.

Developmental cysts of the head and neck comprises of thyroglossal duct cysts, dermoid and epidermoid cysts, branchial cleft cysts, and intraoral lymphoepithelial cysts.

Thyroglossal Duct Cyst

Th yroglossal cyst develops from remnants of thyroglossal duct. ●

Th e exact etiology for stimulation of remnants to form cyst is unknown. ●

Th e infl ammatory conditions which form reactive hyperplasia of the lymphoid tissue ●

adjacent to the remnants of thyroglossal duct may stimulate the epithelial remnants.

Clinical featuresAge ● : <10 yearsGender ● : No gender predilectionLocation ●

Extraoral lesions: Midline of the neck in the area of the hyoid bone ❍

Intraoral lesions: Floor of the mouth ❍

Signs and symptoms ●

Th e cyst usually presently as a soft, painless, fl uctuant, movable swelling unless it is ❍

complicated by secondary infection.If the cyst maintains an attachment to the hyoid bone or tongue, it will move verti- ❍

cally during swallowing or protrusion of the tongue.If cysts are located high in the tract, they may cause dysphonia or dyspnea. ❍

HistopathologyTh e cysts are lined by ciliated pseudostratifi ed columnar epithelium or stratifi ed ●

squamous epithelium. Frequently, thyroid tissue is seen in the fi brous capsule. ●

Th e cysts located in the lingual area show mucous cells in the cyst lining and seromu- ●

cous glands in the capsule. Sometimes, lymphoid tissue with prominent germinal centers is seen. ●

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Prognosis and predictive factorsSurgical excision of cyst with tract and its branches is recommended. ●

Th e intimate association of the tract with hyoid bone mandates simultaneous re- ●

moval of the central portion of the hyoid bone to ensure complete removal of the tract.Recurrence is rare. ●

Occasionally malignant transformation (thyroid carcinoma or squamous cell carcino- ●

ma) has been observed.

Dermoid and Epidermoid Cysts

Dermoid cysts are developmental cysts arising from entrapped ectodermal tissue which is lined by epidermis with skin appendages in the fi brous capsule. Epidermoid cysts are similar cysts lined by epidermis, but without appendages in the fi brous capsule.

Pathogenesis

Dermoid cystUnknown. ●

Intermingling of stomodeal ectoderm and endoderm at 32nd day of IU life. ●

Th e sequestration of skin and subsequent implantation of it along the lines of embry- ●

onic closure.

Epidermoid cystSequestration and implantation of epidermal rests during embryonal period. ●

Occlusion in pilosebaceous unit or in eccrine ducts. ●

Iatrogenic or surgical implantation of epithelium into the jaw. ●

Syndromes: Gardner’s syndrome, basal cell nevus syndrome, and pachyonychia con- ●

genita.

Clinical featuresAge ● : 15–35 yearsGender ● : Male predilectionLocation ● : Th e fl oor of the mouthSigns and Symptoms ●

Th e intraoral swelling lifts the tongue and may lead to diffi culty in speaking, eating, ❍

and breathing.Deeper lesions between the geniohyoid and mylohyoid muscles produce a submen- ❍

tal swelling in the neck giving the patient a double-chin appearance. Th e cysts tend to be small in infancy and enlarge during adolescence. ❍

HistopathologyUsually, both dermoid and epidermoid cysts are lined by orthokeratinized stratifi ed ●

squamous epithelium resembling epidermis. Th e dermoid cyst capsule is characterized by the presence of one or more dermal ap- ●

pendages such as hair follicles, sweat glands or sebaceous glands. Hair is very rarely found. Th e lumen is usually fi lled with keratin.Epidermoid cysts contain abundant keratin in the lumen with no dermal appendages ●

in the capsule.



Forme frusta ● of a teratoma: Simpler dermal cysts which do not contain tissues from all the three germ layers. ● Teratoid cyst: A cystic form of teratoma that contains a variety of germ layer deriva-tives:

Skin appendages including hair follicles, sebaceous glands, and sweat glands. ❍

Connective tissue elements such as muscle, blood vessels, and bone. ❍

Endodermal structures such as gastrointestinal lining. ❍

Note: Th ese intraoral epidermoid cysts should not be confused with the more common epidermoid cyst of the skin, which is a nonteratomatous lesion that arises from the hair follicle.

Prognosis and predictive factorsSurgical excision is the mainstay in the management protocol and recurrence is seldom ●

noticed.An unusual complication reported from an oral epidermoid cyst is sialadenitis due to ●

pressure on the submandibular salivary duct.

TUMORS OF ODONTOGENIC ORIGIN

CLASSIFICATION OF ODONTOGENIC TUMORS (WHO, 2005)

Classify odontogenic tumors of the jaws.

Odontogenic tumors of the jaws are classifi ed as follows:Benign ●

Odontogenic epithelium with mature fi brous stroma without odontogenic ectomes- ❍

enchymeAmeloblastoma ❒

Adenomatoid odontogenic tumor ❒

Squamous odontogenic tumor ❒

Calcifying epithelial odontogenic tumor ❒

Keratocystic odontogenic tumor ❒

Odontogenic epithelium with odontogenic ectomesenchyme with or without hard ❍

tissue formationAmeloblastic fi broma ❒

Ameloblastic fi brodentinoma ❒

Ameloblastic fi bro-odontoma ❒

Complex odontoma ❒

Compound odontoma ❒

Odontoameloblastoma ❒

Calcifying cystic odontogenic tumor ❒

Odontogenic ectomesenchyme with or without odontogenic epithelium ❍

Odontogenic fi broma ❒

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Odontogenic myxoma ❒

Cementoblastoma ❒

Malignant ●

Odontogenic carcinomas ❍

Malignant ameloblastoma ❒

Ameloblastic carcinoma ❒

Ghost cell odontogenic carcinoma ❒

Clear cell odontogenic carcinoma ❒

Primary intraosseous squamous cell carcinoma ❒

Odontogenic sarcomas ❍

Ameloblastic fi brosarcoma ❒

Ameloblastic fi brodentino- and fi bro-odontosarcoma ❒

AMELOBLASTOMA

Discuss pathogenesis, clinical features, radiological features, and histopathology of ameloblastoma.

(Synonyms: adamantinoma, adamantoblastoma)Th e ameloblastoma is a true neoplasm of enamel organ-type tissue which does not undergo diff erentiation to the point of enamel formation.

Robinson defi ned ameloblastoma as “usually unicentric, nonfunctional, intermittent in growth, anatomically benign and clinically persistent.” Based on clinical, radiological, and histopathological characteristics, the following variants of ameloblastoma can be presently distinguished:

Classic solid/multicystic ameloblastoma (SMA) ●

Unicystic ameloblastoma (UA) ●

Peripheral ameloblastoma (PA) ●

Desmoplastic ameloblastoma (DA) ●

Note: Recently, desmoplastic ameloblastoma is added as a new subtype rather than a histologic variant due to following reasons:

Diff erence in anatomic location compared to other forms of ameloblastoma. ●

Unusual radiological appearance. ●

Atypical morphology of epithelial component. ●

Marked stromal desmoplasia. ●

Explain pathogenesis, clinical features, radiological features, and histopathology of solid/multicystic ameloblastoma.

Describe the histopathology of solid/multicystic ameloblastoma.

(Synonym: conventional ameloblastoma)Th e term ameloblastoma was coined by Churchill in 1934. It is the second most common odontogenic neoplasm (fi rst being odontoma).

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Defi nition: Th e solid/multicystic ameloblastoma (SMA) is a slow growing, locally inva-sive, epithelial odontogenic tumor of the jaws with a high rate of recurrence if not removed adequately, but with virtually no tendency to metastasize.

Pathogenesis: Tumor can arise from any of the following:Cell rests of enamel organ. ●

Disturbances in developing enamel organ. ●

Epithelium of odontogenic cysts: dentigerous cysts or odontomas. ●

Heterotrophic epithelium in other parts of body especially in pituitary gland (Rathke’s ●

pouch ameloblastoma).

Clinical featuresAge ● : 30–40 yearsGender ● : Male predilectionLocation ● : Posterior region of the mandibleSigns and symptoms ●

It is a slow growing, but locally invasive tumor with a high rate of recurrence if not ❍

removed adequately.Initially, few or no clinical signs are seen. ❍

In later stages, there will be a gradual increase in swelling leading to facial deformity. ❍

Continued enlargement of tumor may cause surrounding bone to become so thin ❍

that crepitation or egg-shell crackling may be elicited.Teeth in the lesional area may become mobile and pathological fracture of jaws may ❍

occur sometimes. Pain may be present only in some cases. It may be either due to pressure of the tu- ❍

mor on peripheral nerves or secondary infection.

Radiological featuresUnilocular type ● : Well-defi ned radiolucency that forms single compartment.Multilocular type ● : It shows number of small, well-defi ned radiolucent areas giving hon-eycomb or larger soap bubble appearance (this appearance is due to trabeculae pattern and reactionary bone response to the lesion).

Histopathology: Th e histological patterns of SMA are as follows:Follicular SMA ●

Plexiform SMA ●

Acanthomatous SMA ●

Granular cell SMA ●

Basal cell SMA ●

Note: Th e categorization of these patterns does not have any signifi cance in determining the clinical management or prognosis of the lesion.

Follicular SMA (Fig. 11.8)Th e tumor consists of islands or follicles of epithelial cells. ●

Th e follicles consist of a central stellate reticulum like cells and peripheral cuboidal or colum- ●

nar cells with reversal of polarity resembling inner enamel epithelium or preameloblasts.Usually, cystic degeneration occurs within these follicles. ●



Plexiform SMA (plexus: network) (Fig. 11.9)Th e epithelium forms continuous anastomosing strands. ●

Tumor epithelium is arranged as a network which is bound by a layer of cuboidal or ●

columnar cells and includes stellate reticulum-like cells.Frequently, cyst formation occurs due to stromal degeneration. ●

Note: Identifi cation of connective tissue stroma will help to distinguish follicular SMA from plexiform SMA. In follicular SMA connective tissue stroma will be present within the follicles, where as in later it is vice versa.

Acanthomatous SMA (Fig. 11.10)It shows squamous metaplasia and/or keratin pearl formation within the islands of ●

tumor cells.Usually, the general pattern of this tumor is of the follicular type. ●

Granular cell SMA Th is tumor, most often the follicular type, shows an extensive granular transformation ●

of the central stellate reticulum-like cells. In some lesions, all cells of the tumor islands or nests are composed of granular cells.

Ameloblastomatous follicles

Peripheral columnar cells

Central stellatereticulum-like cells

Cystic degeneration

Fig. 11.8. Follicular SMA.

Anastomosing strands

Stellate reticulum-like cells

Columnar cells

Stromal degeneration

Fig. 11.9. Plexiform SMA.



Th e granular cells may be cuboidal, columnar, or rounded in shape and cytoplasm is ●

fi lled with acidophilic granules.Th e cytoplasmic granules have been identifi ed ultrastructurally as lysosomal aggregates ●

that might be caused due to increased apoptotic cell death and associated phagocytosis by neighboring neoplastic cells.

Basal cell SMATh e tumor island shows central basaloid cells and peripheral cuboidal cells. ●

No stellate reticulum is present in the central portion of the islands/nests. ●

Diff erential diagnosisKeratocystic odontogenic tumor ●


Pindborg’s tumor ●

Prognosis and predictive factors Treatment should include excision with an adequate margin of uninvolved tissues. ●

Lesions involving the posterior maxilla, demonstrate the poorest prognosis. ●

Long-term follow up is essential, since recurrences have been noted even after 10 years ●

of the initial treatment.

Describe pathogenesis, clinical features, radiological features, and histopathology of unicystic ameloblastoma.

Discuss the histopathology of unicystic ameloblastoma.

(Synonym: cystogenic ameloblastoma)

Defi nition: Th e unicystic ameloblastoma (UA) represents an ameloblastoma variant, pre-senting as a cyst.

PathogenesisReduced enamel epithelium undergoing ameloblastic transformation with subsequent ●

cyst development.Ameloblastoma arises in a dentigerous cyst or other types of odontogenic cysts. ●

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Ameloblastomatousfollicles

Peripheralcolumnar cells

Central stellatereticulum-like cells

Squamous metaplasia

Fig. 11.10. Acanthomatous SMA.



Solid ameloblastoma undergoes cystic degeneration. ●

de novo ● (on its own) cystic neoplasm.

Clinical featuresAge ● : 20–30 yearsGender ● : No sex predilectionLocation ● : Posterior region of the mandibleSigns and symptoms ●

Usually most of the lesions are asymptomatic. ❍

Painless, localized swelling of the jaws, and lip numbness are seen. ❍

Pain and discharge are seen among secondarily infected lesions. ❍

Radiological featuresIt appears as a well-circumscribed unilocular radiolucency with sclerotic border. ●

Usually associated with impacted mandibular third molar tooth. ●

Histopathology: Th e unicystic ameloblastoma are of three distinct types (Fig. 11.11).

Luminal unicystic ameloblastomaEpithelial lining shows cuboidal or columnar basal cells with hyperchromatic, palisad- ●

ing, and polarized nucleus. Cytoplasmic vacuolization, intercellular spacing, and sub-epithelial hyalinization is also seen (Vickers and Gorlin criteria).Th e overlying epithelial cells resemble stellate reticulum. ●

Intraluminal unicystic ameloblastomaOne or more nodules of epithelial lining project into the cystic lumen. ●

Sometimes the nodule projecting into the lumen shows a plexiform pattern – Plexi- ●

form unicystic ameloblastoma.

Intramural unicystic ameloblastoma In this type, the fi brous wall of the cyst is infi ltrated by islands of follicular or plexiform ameloblastoma.

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Fig. 11.11. Histopathology of unicystic ameloblastoma: (1) luminal unicystic ameloblastoma, (2) intraluminal unicystic ameloblastoma, and (3) intramural unicystic ameloblastoma.



Diff erential diagnosisOdontogenic keratocyst. ●

Dentigerous cyst. ●

Calcifying epithelial odontogenic cyst. ●

Prognosis and predictive factorsUsually enucleation is the treatment of choice. ●

Th e luminal variant does not infi ltrate into the surrounding bone, so no further treat- ●

ment is required. Th e mural variant is excised and further treatment will depend upon the depth of epi- ●

thelial invasion into the cyst wall. Limited invasion lesions: Careful follow up. ❍

Deep invasion lesions: Surgical intervention with long-term follow up. ❍

Describe peripheral ameloblastoma. (Synonyms: soft tissue ameloblastoma, ameloblastoma of the gingiva)

Defi nition: Th e extraosseous/peripheral ameloblastoma (PA) is the extraosseous counter-part of the intraosseous solid/multicystic ameloblastoma.Pathogenesis

Remnants of odontogenic epithelium. ●

Basal cell off -shouts (hamartias) of gingival epithelium. ●

Clinical featuresAge ● : 30–40 yearsGender ● : No sex predilection Location ● : Soft tissues overlying the tooth bearing areas of mandibleSigns and symptoms ●

It appears as a painless, nonulcerated sessile or pedunculated mass ❍

Clinically it resembles as fi broma or pyogenic granuloma ❍

Radiological featuresUsually, no evidence of radiographic appearance is seen. ●

Sometimes, superfi cial erosion of the bone (cupping or saucerization) may be seen. ●

HistopathologyLesion shows islands of ameloblastic epithelium in the lamina propria underneath the ●

surface epithelium.Th e proliferating epithelium shows features of follicular or plexiform intraosseous ●

ameloblastoma. Diff erential diagnosis

Peripheral odontogenic fi broma. ●

Peripheral variant of the squamous odontogenic tumor. ●

Odontogenic gingival epithelial hamartoma. ●

Prognosis and predictive factors PA does not show invasive behavior and conservative excision is the treatment of choice. ●

Th e recurrence rate is low. ●

Long-term follow-up is recommended. ●

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Write about desmoplastic ameloblastoma.

Defi nition: Desmoplastic ameloblastoma (DA) is characterized by an unusual histomor-phology with extensive stromal collagenization or desmoplasia, hence the tumor is named as desmoplastic ameloblastoma.

Pathogenesis: Similar to solid/multicystic ameloblastoma.

Clinical featuresAge ● : 40–50 yearsGender ● : Male predilectionLocation ● : Anterior region of the mandibleSigns and Symptoms: ● It presents as an asymptomatic painless swelling.

Radiological featuresIt shows mottled, mixed radiolucency, or radiopacity with diff use margins (suggesting ●

a fi bro-osseous lesion).Resorption of tooth roots is commonly seen. ●

Histopathology Th e epithelial tumor islands are often irregular in shape with an almost pathognomic ●

animal-like confi guration.Epithelial cells at the periphery of the islands are cuboidal or columnar in shape, where- ●

as center of the epithelial islands appears hypercellular with spindle shaped or squama-toid epithelial cells. Extensive stromal desmoplasia (increased fi brosis) seem to compress or squeeze the ●

odontogenic epithelial islands from the periphery.

Note: Usually, DA with areas of follicular or plexiform ameloblastoma is called as hybrid lesion of ameloblastoma.

Diff erential diagnosisOdontogenic keratocyst ●



Prognosis and predictive factors: Surgical excision with an adequate margin of unin-volved tissues is recommended.

ADENOMATOID ODONTOGENIC TUMOR

Write about pathogenesis, clinical features, radiological features, and histopathology of adenomatoid odontogenic tumor.

Discuss the histopathology of adenomatoid odontogenic tumor.(Synonyms: adenoameloblastoma, ameloblastic adenomatoid tumor)In 1969, Philipsen and Birn introduced the term adenomatoid odontogenic tumor (AOT). Till then it was known as adenoameloblastoma.

Defi nition: Adenomatoid odontogenic tumor (AOT) is a benign hamartomatous lesion, composed of odontogenic epithelium in a variety of histoarchitectural patterns, embedded

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in a mature connective tissue stroma, and characterized by slow but progressive growth (WHO, 2005).

PathogenesisDerived from dental lamina or its remnants. ●

Disturbances during presecretory stage of enamel organ. ●

Clinical featuresAOT occurs in two forms: ●



Age ● : 20–30 yearsGender ● : Female predilectionLocation ● : Anterior region of the maxilla – both central and peripheral variantSigns and symptoms ●

It appears as slow growing, bony hard swelling which is often associated with ❍

unerupted upper canine.Displacement of the regional teeth, mild pain, and expansion of the cortical bones ❍

are usually seen.Th e extraosseous variant produces a solitary, painless, and asymptomatic nodular ❍

gingival swelling.

Radiological featuresIntrabony variant occurs as a unilocular radiolucency with a smooth corticated bor- ●

der.About two-thirds of the intrabony variants show radiopaque foci within the radiolu- ●

cent lesion.Th e peripheral variants may show saucerization of the alveolar bone crest. ●

Radiological variants are as follows (Fig. 11.12): ●

Intraosseous follicular type (F): It is located around the crown and often covers part of ●

the root of an unerupted tooth (envelopmental type).Extraosseous follicular types (E) ●

E1: No relation to tooth structures. ❍

E2: Inter-radicular, adjacent roots diverge apically due to tumor expansion. ❍

E3: Superimposed on root apex. ❍

E4: Superimposed on mid-third of the root. ❍

Extraosseous peripheral type (P): Exhibit slight erosion of the alveolar bone crest. ●

Histopathology: It shows a combination of the following patterns:

Rosette pattern: It is composed of cuboidal or columnar epithelial cells forming rosette-like structures with minimal mature fi brous connective tissue stroma. Between the epithelial cell nodules and in center of rosette-like confi guration, amorphous eosinophilic material (tumor droplets) is present.

Tubular or ductal pattern (hence the name, adenomatoid-gland like): It shows duct-like spaces lined by a single row of cuboidal cells with empty or amorphous material in the lumen.



Solid pattern: It is composed of varying size nodules exhibiting well-defi ned squamous cell with prominent intercellular bridges. Th ese nodules may contain pools of amorphous eosinophilic material and globular masses of calcifi ed substances.

Trabecular or cribriform pattern: It is composed of one to two cells thickness interconnect-ing epithelial strands. Usually this pattern is seen at periphery of the tumor.

Sometimes a whorled pattern with a thin layer of tumors droplets between opposing ●

rows of columnar cells is seen.Spindle shaped cells are seen between these epithelial structures. ●

In some cases AOT may occur with CEOT – combined odontogenic tumors. ●

Hyaline, dysplastic dentinoid material, or calcifi ed osteodentin can also occur in some ●

areas of tumor.

Diff erential diagnosisDentigerous cyst ●

Globulomaxillary cyst ●


Prognosis and predictive factorsAOTs are cured by local excision. ●

Recurrences are extremely rare. ●

SQUAMOUS ODONTOGENIC TUMOR

Discuss the pathogenesis, clinical features, radiological features, and histopathology of squamous odontogenic tumor.

Defi nition: It is a locally infi ltrating neoplasm consisting of islands of well-diff erentiated squamous epithelium in a fi brous stroma.

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E1

E3

E4E2

P

F

Fig. 11.12. Radiological variants of adenomatoid odontogenic tumor.



PathogenesisRemnants of odontogenic epithelium ●

Hamartias ●

Clinical featuresAge ● : 20–30 yearsGender ● : Male predilectionLocation ●

Maxilla: Incisor-cuspid area ❍

Mandible: Molar-bicuspid area ❍

Signs and symptoms ●

Asymptomatic lesion often develops from periodontal ligament of permanent teeth. ❍

Slow-growing swelling, mobility of teeth, and moderate pain may be present. ❍

Radiological features: Well-defi ned unilocular triangular radiolucency is seen between the roots of adjacent teeth.Histopathology

It is composed of round or oval-shaped islands of well-diff erentiated squamous epithe- ●

lium.Individual tumor islands reveal a peripheral layer of low cuboidal or even fl at epithelial ●

cells.Th e central squamous cells are very uniform in size and they do not exhibit pleomor- ●

phism, nuclear hyperchromatism, or mitotic activity.Sometimes, individual epithelial islands may undergo central microcystic degeneration ●

following single cell keratinization.Few islands may enlarge and contain laminar calcifi ed material. ●

Globular eosinophilic material can be seen within the islands, which are not amyloid. ●

Diff erential diagnosisLateral periodontal cyst. ●

Ameloblastoma (acanthomatous pattern). ●

Squamous cell carcinoma. ●

Prognosis and predictive factorsConservative surgical treatment is usually suffi cient. ●

Recurrences are rare. ●

CALCIFYING EPITHELIAL ODONTOGENIC TUMOR

Describe pathogenesis, clinical features, radiological features, and histopathology of calcifying epithelial odontogenic tumor.

Explain the histopathology of calcifying epithelial odontogenic tumor.

Write about calcifi cations in calcifying epithelial odontogenic tumor.(Synonym: Pindborg tumor)Th e calcifying epithelial odontogenic tumor ( CEOT) was fi rst reported by Pindborg (1955), hence the eponym Pindborg tumor.

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Defi nition: It is a locally invasive epithelial odontogenic neoplasm, characterized by the presence of amyloid material that may become calcifi ed (WHO, 2005).

Pathogenesis: It may arise fromReduced enamel epithelium. ●

Cell rests of Serre or hamartias. ●

Clinical features CEOT occurs in two forms: ●



Age ● : 20–60 yearsGender ● : Male predilectionLocation ● : Posterior region of mandibleSigns and symptoms ●

Intraosseous lesion presents as a painless, slow-growing swelling, often associated ❍

with unerupted tooth. Usually, maxillary central lesions produce nasal congestion, epistaxis, and headache. ❍

Extraosseous lesion presents as a painless, fi rm gingival mass, often resembles pyo- ❍

genic granuloma.

Radiological featuresUsually, intraosseous lesions show irregular unilocular or multilocular radiolucent areas ●

containing radiopaque masses of varying sizes, which gives a characteristic snow-driven appearance.Th e peripheral lesion sometimes causes saucerization of the underlying bone. ●

Histopathology (Fig. 11.13)Th e basic histologic pattern of CEOT includes variable combination of odontogenic ●

epithelium and calcifi ed structures . Th e tumor epithelium is composed of polyhedral epithelial cells with prominent inter- ●

cellular bridges either arranged in a closely packed in large sheets or as a scattered small islands in a bland fi brous connective tissue stroma.Th e nuclei are frequently pleomorphic, but mitotic fi gures are rare. ●

Amyloid material

Sheet of polyhedralepithelial cells

Liesegang rings

Fig. 11.13. Calcifying epithelial odontogenic tumor.



Clear cell variant: In this type, the tumor cells exhibit a clear vacuolated cytoplasm rather than an eosinophilic cytoplasm. Th e nucleus may be round or oval in shape, which will be present at the center of the cell or fl attened against the basement membrane.

Amyloid material of CEOT: A homogenous, eosinophilic substance which stains metach-romatically with crystal violet, positively with Congo red, and fl uoresces under ultravio-let light with thiofl avin T in a fashion similar to amyloid. However, the exact nature of amyloid substance in CEOT is still not known.

Calcifi cations in CEOTUsually occurs as dark hematoxyphillic concentrically laminated calcifi ed masses – Lie- ●

segang rings.Sometimes it may occur in the form of globules. ●

Cementum-like components in CEOT It occurs as well-circumscribed darkly staining hematoxyphillic globules in the connec- ●

tive tissue stroma.Th e mechanism of formation is still unclear, but they are thought to be dystrophic ●

calcifi cations.Slootweg (1991) suggested that the amyloid-like material is an inductive stimulus for ●

the stromal cells to diff erentiate toward production of a collagenous matrix that is des-tined to mineralize and resemble cementum.

Diff erential diagnosisCalcifying epithelial odontogenic cyst. ●

Adenomatoid odontogenic tumor. ●

Intraosseous squamous cell carcinoma. ●

Prognosis and predictive factorsIt is a locally invasive tumor. Small tumors may be enucleated, but larger lesions require ●

local resection. Long-term follow-up is recommended. ●

AMELOBLASTIC FIBROMA

Explain ameloblastic fi broma.

(Synonym: fi broadamantoblastoma)

Defi nition: Ameloblastic fi broma (AF) consists of odontogenic ectomesenchyme resem-bling the dental papilla and epithelial strands, and nests resembling dental lamina and enamel organ. No dental hard tissues are present. If there is dentin formation, the lesion is referred to as ameloblastic fi brodentinoma (AFD) (WHO, 2005).

Pathogenesis: AF may arise from the normal tooth anlage before the primitive induction of ectomesenchymal cells for hard tissue formation.

Clinical featuresAge ● : 10–20 yearsGender ● : Male predilection

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Location ● : Posterior region of the mandible Signs and symptoms ●

It occurs as a painless, slow-growing expansile lesion. ❍

Usually lesions are identifi ed during routine radiographic examination. ❍

Radiological feature: It appears as a well-defi ned unilocular or multilocular radiolucency with a sclerotic border.

HistopathologyAF consists of epithelial and ectomesenchymal component. ●

Epithelial component composed of proliferating odontogenic epithelium arranged in ●

the form of islands and strands.Islands show peripheral cuboidal or columnar cells with central stellate reticulum-like cells. ●

Strands often reveal as a double or triple layer of cuboidal cells including stellate retic- ●

ulum-like cells.Ectomesenchymal component includes rounded or angular-shaped cells with few deli- ●

cate collagen fi brils.

Diff erential diagnosisAmeloblastoma ●

Calcifying odontogenic cyst ●


Prognosis and predictive factorsTreatment consists of enucleation and curettage. ●

Recurrence may occur but this does not justify initial aggressive treatment. ●

Rarely, AF may progress to malignancy (ameloblastic fi brosarcoma). ●

ODONTOMA

Explain pathogenesis, clinical features, radiological features, and histopathology of odontomas.

Odontomas are the most common odontogenic tumors. Odontoma is a mixed odontogenic tumor composed of both epithelial and

ectomesenchymal components. In odontomas, epithelial and ectomesenchymal tissues and their respective cells may appear normal morphologically, but they seem to have a defi cit in structural arrangement. Th is defect has led to opinion that odontomas are hamartomatous lesions or malformations rather than a true neoplasm.

Th ere are two types of odontomas ● Complex odontoma: Dental tissues are well arranged. ● Compound odontoma: Dental tissues are disorderly arranged.

Etiology: Unknown, but several hypothesis have been proposed includingLocal trauma ●

Infection ●

Family history ●

Genetic mutation ●

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PathogenesisIt is a self-limiting developmental anomaly or hamartomatous malformation found as ●

nondescript masses of dental tissues.Factors that cause anomalous tissue development in odontomas are ●

Altered ectomesenchymal interaction during tooth development. ❍

Alteration in the mineralization mechanisms. ❍

Write about pathogenesis, clinical features, radiological features and histopa-thology of complex odontomas.

Elucidate the histopathology of complex odontomas.

Defi nition: Malformation in which all the dental tissues are represented, individual tissues being mainly well-formed but occurring in a more or less disorderly pattern (WHO, 2005).

Clinical featuresAge ● : 10–20 yearsGender ● : Male predilectionLocation ● : Posterior region of the mandibleSigns and symptoms ●

It appears as round or ovoid shaped, slow growing, and painless swelling. ❍

Usually size of the lesion ranges from 3 to 4 cm in diameter. ❍

Often detected during routine radiographic examination for unerupted tooth or ❍

retained deciduous tooth.

Radiological features: It depends on developmental stages of the lesion:First stage ● : Radiolucent lesion is seen due to lack of calcifi cation (Weiches odontoma). Second stage ● : Partial calcifi cation is seen.Th ird stage ● : Radiopaque mass of dental hard tissues surrounded by a thin radiolucent zone is seen.

Histopathology It consists of a disordered mixture of dental tissues, often spherical in shape. ●

Cementum-like structures often admixed with the dentinoid substance, small spaces ●

with pulp tissue, enamel matrix, and epithelial remnants are seen.Empty spaces and clefts are caused due to loss of enamel during the process of decal- ●

cifi cation.A thin, fi brous capsule is seen surrounding the lesion. ●

Sixteen percent of complex odontoma shows areas of ghost cells. ●

Prognosis and predictive featuresComplex odontomas are treated by local excision. ●

Recurrence is rarely reported. ●

Write about pathogenesis, clinical features, radiological features and histopa-thology of compound odontomas.

Describe the histopathology of compound odontomas.

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Defi nition: A malformation in which all the dental tissues are represented in a more orderly pattern than in the complex odontoma, so that the lesion consists of many tooth-like structures. Most of these structures do not morphologically resemble the teeth of the normal dentition, but in each structure, enamel, dentin, cementum, and pulp are arranged as in normal tooth (WHO, 2005).

Clinical featuresAge ● : 10–20 years Gender ● : No sex predilection Location ● : Anterior region of the maxillaSigns and symptoms ●

It is a painless, slow-growing lesion with a limited growth potential than complex ❍

odontomas.Growth potential ends with the tooth forming period. ❍

Often detected during routine radiographic examination for unerupted tooth or ❍

retained deciduous tooth.Compound odontomas may be associated with Gardner’s syndrome ❍ .

Radiological featuresIt comprises of a radiopaque mass with number of teeth-like structures arranged in a ●

disorderly fashion.Th ese denticles are miniaturized and malformed. ●

Th e lesion is surrounded by a narrow radiolucent rim corresponding to a fi brous cap- ●

sule at periphery. Histopathology

It is composed of denticles showing enamel, dentin, cementum, and pulp tissues in a ●

regular arrangement.Higher degree of morphodiff erentiation is seen. ●

Usually small, but large lesions contain up to hundred denticles. ●

Th e lesion is often surrounded by a thick fi brous capsule. ●

Th ree percent of odontomas may contain ghost cells. ●

Diff erential diagnosisCalcifying epithelial odontogenic tumor ●

Ameloblastic fi bro-odontoma ●

Osteoma ●

Prognosis and predictive featuresCompound odontomas are treated by local excision. ●

Recurrence is rarely reported. ●

METASTASIZING MALIGNANT AMELOBLASTOMA

Discuss pathogenesis, clinical features, radiological features, and histopathology of metastasizing malignant ameloblastoma.

Defi nition: Metastasizing malignant ameloblastoma is an ameloblastoma that metastasis in spite of a benign histologic appearance (WHO, 2005).

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PathogenesisOrigin is likely to be same as that of benign ameloblastoma. ●

Th e spread of tumor could result from either due to ●

Increasing malignant behavior stimulated by multiple recurrences, or ❍

Implantation of the tumor into lymphatic or blood vessels by repeated surgical in- ❍

terventions.

Factors that appear to contribute for potential metastatic spreadDuration of neoplasm. ●

Extent and size of the initial tumor. ●

Initial type of surgery (conservative versus radical therapy). ●

Multiple recurrences and respective surgery interventions. ●

Most common sites to metastasis: Lung, hilar lymph node, bones, skull, vertebrae and femur, cervical lymph nodes, liver, brain, other nodes, spleen, and kidney.

Clinical featuresAge ● : >50 yearsGender ● : Male predilectionLocation ● : Posterior region of the mandibleSigns and symptoms: ● Painful swelling, delayed tooth eruption, ulceration, and tooth mobility are the most common symptoms.

HistopathologyTh e primary jaw tumor and metastatic deposits show histopathological features similar ●

to conventional ameloblastoma.Usually, follicular or plexiform ameloblastoma histopathological patterns are seen. ●

Eighty percent of the lesions occur in pure form. ●

It does not show greater cytological atypia or mitotic activity. ●

Rarely, necrosis in tumor islands and areas of dystrophic calcifi cation is seen. ●

Prognosis and predictive factors: Poor prognosis.

AMELOBLASTIC CARCINOMA

Explain pathogenesis, clinical features, radiological features, and histopathology of ameloblastic carcinoma.

(Synonym: carcinoma ex ameloblastoma)

Defi nition: Ameloblastic carcinoma (AC) is a rare primary odontogenic malignancy that combines the histological features of ameloblastoma with cytological atypia. Th is will be the case even in the absence of metastases (WHO, 2005).

Pathogenesis: It may arise as ex ameloblastoma or ex odontogenic cyst ●

de novo ● lesion

Clinical featuresAge ● : >50 years

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Gender ● : Male predilectionLocation ● : Posterior region of the mandibleSigns and symptoms ●

Swelling, pain, trismus, and dysphonia are evident. ❍

Rapid growth of the tumor is an important feature. ❍

Commonly, mental nerve paresthesia is seen. ❍

Radiological featuresResembles solid/multicystic ameloblastoma, but in most cases, they present as ill-de- ●

fi ned radiolucencies.Foci of radiopacities probably due to dystrophic calcifi cation are observed. ●

HistopathologyIt is composed of islands and cords of ameloblastomatous odontogenic epithelium in ●

an infi ltrating pattern within the stroma of mature fi brous tissue.Epithelium component shows less orderly pattern of peripheral columnar or cuboidal ●

cells with reversal of polarity and central stellate reticulum-like cells.Characteristic features of malignant odontogenic epithelium includes ●

Nuclear hyperchromatism. ❍

Nuclear enlargement with granular stippled nucleoplasm. ❍

Cellular and nuclear pleomorphism. ❍

Increased nuclear-cytoplasmic ratio. ❍

Increased mitotic activity with abnormal forms of mitosis. ❍

Individual cell keratinization and keratin pearl formation. ❍

Diff erent histologic patterns may be noted – highly diff erentiated squamous cell to ❍

poorly diff erentiated basaloid cells.Connective tissue stroma shows dense collagen fi bers, necrosis, dystrophic calcifi ca- ●

tions, few infl ammatory cells, and hemorrhage.Rarely, clear cell diff erentiation is seen in epithelial component. ●

Prognosis and predictive factorsMaxillary ameloblastic carcinomas demonstrate tumor-related deaths or pulmonary ●

metastases. Mandibular counterparts behave in a similar manner, where local recurrences are likely ●

to precede metastases.

PRIMARY INTRAOSSEOUS SQUAMOUS CELL CARCINOMA

Write about primary intraosseous squamous cell carcinoma.

(Synonym: primary intra-alveolar epidermoid carcinoma)

Defi nition: Primary intraosseous squamous cell carcinoma (PIOSCC) is a central jaw carcinoma derived from odontogenic epithelial remnants. Subcategories of PIOSCC include (1) a solid tumor that invades marrow spaces and induces osseous resorption, (2) squamous cancer arising from the lining of an odontogenic cyst, and (3) a squamous cell carcinoma in association with other benign epithelial odontogenic tumors. When the

Q.



tumor destroys the cortex and merges with the surface mucosa, it may be diffi cult to dis-tinguish between a PIOSCC and a true carcinoma arising from the oral mucosa (WHO, 2005).

Pathogenesis: It may arise from Reduced enamel epithelium or remnants of odontogenic epithelium. ●

Transformation of odontogenic cysts and tumors like KCOT and dentigerous cyst. ●

Clinical featuresAge ● : >50 yearsGender ● : Male predilection Location ● : Posterior region of the mandibleSigns and symptoms ●

Persistent postextraction pain, toothache, periodontal disease, pericoronitis, sensory ❍

disturbances, or swelling are the common presenting symptoms.Th e diagnosis has to be considered in cases where initial dental treatment has ❍

failed.

Radiological feature: Diff use radiolucency with poorly defi ned irregular margins is seen.

HistopathologyIt shows distinct odontogenic pattern with basal cells arranged in an alveolar or plexi- ●

form pattern with palisading arrangement at the periphery.Squamous metaplasia and keratinization may be seen. ●

Few cases show foci of degeneration within epithelial islands. ●

Since histopathology of PIOSCC is not pathognomic, a diagnosis can be made only if ●

there is no evidence of the tumor arising from either the oral mucosa or from odonto-genic cysts.

Prognosis and predictive factors: Poor prognosis.

Frequently Asked Questions

1. Write about dentigerous cyst.

2. Discuss pathogenesis, clinical features, radiological features, and histopathol-ogy of lateral periodontal cyst.

3. Write a short note on apical cyst.

4. What is ameloblastoma?

5. Discuss briefl y adenomatoid odontogenic tumor (AOT).

6. Write about Pindborg tumor.

7. Give a brief account of odontogenic myxoma.

8. Write a short note on odontomas.


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