Dermoid Cysts of Floor of the Mouth: Report of Four Cases

Rephael Zeltser, DMD, Dip Odont (Pretoria), Isaac Milhem, DMD, Badri Azaz, DMD, and Oscar Hasson, DDS

(E&toria] Comment: The authors have nicely illustrated their approach to this unusual problem. Many physicians would use computed tomography to image these lesions and may opt for an external approach rather than the transoral approach.)

Dermoid cysts, unusua l lesions of unc lear etiology, are cons ide red to be deve lopmenta l anomalies . They may be found at var ious sites, but not usua l ly on the floor of the mouth . Four ne w cases are p resen ted in this paper. The clinical, radiographic , histological and scan- ning e lec t ron mic roscopy (SEM) features of de rmoid cyst are described. The advoca ted surgical approach is an intraoral t echn ique th rough the l ingual f renulum.

Dermoid cysts are pr imar i ly found in the poster ior anal region and ovaries. They occur less f requent ly in the head and neck region, and the floor of the m o u t h is not a c o m m o n site for this cyst. A 25-year rev iew by N ew and Erich 1 showed that, of 1,495 cases, 6.9% (103 cases) of de rmoid cysts occur red in the head and neck region, but on ly 1.6% (24 cases) were in the floor of the mouth . 1 The les ion has also been found in several rare s i t es - - the uvu la 2 and the bone. 3

Several theor ies a t t empted to expla in the origin of these cysts. Several researchers postu- lated that de rmoid cysts of the floor of the m o u t h de r ived from enc lavement of epi thel ia l cells or debris in the mid l ine dur ing closure of the mandibu la r and hyo id branchia l arches. 4-6 The t raumat ic implan ta t ion theory has been less advoca ted because significant in jury to the submenta l area is usua l ly absent.

From the Department of Oral and Maxlllofaclal Sur- gery, Hebrew Un=verslty, Faculty of Dental Medicine, Hadassah Medical Center, Jerusalem, Israel

Address reprint requests to R. Zeltser, DMD, Oral and Maxllofaclal Surgery, Hadassah Medical Center, POB 12272, Jerusalem, Israel

Copyright © 2000 by W.B Saunders Company 0196-0709/2101-0010510.00/0

Dermoid cysts of the floor of the m o u t h usua l ly occur in young adults, especia l ly dur- ing the 2nd and 3rd decade, wi th no sex p red i l ec t ion 1,5,6,7 but are rarely found in neo- nates or infants. 6,8 Clinically, they present as a s low-growing, painless swell ing in the floor of the mouth , usua l ly of doughy consistency, that may cause diff icul ty in eating, speaking, and, in ext reme cases, breathing. 9 Swell ing in the submenta l area occurs w h e n the cyst lies inferior to the gen iohyo id muscle , giving the pat ient a double -ch in appearance. Surgical excis ion by an intraoral approach is the treat- men t of choice. Mal ignant t ransformat ion is unusual . 1° Recurrences , a l though rare, may occur if the cyst is inadequa te ly removed. 11

MATERIALS AND M E T H O D S

Four cases of dermoid cyst on the floor of the mouth were treated at the OMFS Department-- Hadassah School of Dental Medicine, Jerusalem, Israel, during an 18-year period between 1974 and 1992 (Table 1). The average age of patients was 19.75 years, ranging from 19 to 32 years, and the male:female ratio was 1:3.

The main complaint was a painless swelling on the floor of the mouth and mildly disturbed speech function and swallowing, over periods of 9 months and 16 months, respectively. Three cysts were located in the midline area of the floor of the mouth (Fig 1A) and one unilaterally on the left side. In all cases, the overlying mucosa and salivary flow from submandibular and sublingual glands were normal.

Extraoral examination showed that all cases pre- sented a soft-tissue distention of the submental region the so-called "double chin" (Fig 1B, C). The general medical history was noncontributory, and regional lymphadenopathy was not present.

Radiographic examination was performed after aspiration, and a contrast medium was injected into the submental swelling, showing the extent and the exact limits of the lesion (Fig 2). The differential diagnosis was dermoid cyst or plunging ranula. Under general anesthesia, an intraoral incision was carried out through the sublingual frenulum and extended up to the orifices of Wharton's ducts. The

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56 ZELTSER ET AL

TABLE 1, Dermold Cysts of the Floor of the Mouth

Age Duration Cases Sex (y r ) Location (me) Signs and Symptoms Treatment

1 F 32 Median 16 Painless, mild speech d~sturbance, Intraoral approach double-chin appearance, normal General anesthesia overlying mucosa, normal sahvary flow

2 M 8 Median 9 Painless, d~fflculty m speech, double- chin appearance, normal overlying mucosa, normal salivary flow

3 F 19 Lateral 12 Painless, double-chin appearance, normal overlying mucosa, normal sahvary flow

4 F 20 Median 12 Painless, difficulty in swallowing and speech, double-chrn appearance, normal overlying mucosa, normal sahvary flow

Intraoral approach General anesthesia

Intraoral approach General anesthesia

Intraoral approach General anesthesia

cysts were enucleated completely without rupture by blunt dissection (Fig 3).

Samples of cyst wall were processed for histologi- cal examination with hematoxylin and eosin (H&E) stains, after fixation in 4% buffered formaldehyde, and embedded in paraffin. Similar samples were

processed for scanning electron microscopy (SEM) examination as follows: Samples were fixed in 2% glutaraldehyde for 1 hour, washed in cacody]ate buffer (0.1 tool/L, PH 7.2), and postfixed in a 1% osmium teroxide solution in 0.1 mol/L cacodylate buffer for i hour. This was followed by dehydration

Fig 1. (A) Dermoid cyst located in the anterior floor of the mouth, while the tongue is displaced upward posteri- orly against the palate. Clinical photographs of 2 patients showing (B) submental mass and (C) "double chin" profile.

DERMOID CYSTS OF FLOOR OF THE MOUTH 57

through a graded series of Ferron 113 solutions in absolute ethanol. After triple rinsing in 100% freon,

~' the samples were vigorously shaken in the air for a few seconds. Under these conditions, the liquid phase of the freon evaporated rapidly, leaving the

Fig 3. (A) Operative photograph showing delivery of the cyst through sublingual midline incision. (B) Cystic specimen delivered intact.

specimens satisfactorily dried. 12 The stubs were coated with gold using a Polaron ESIO0 sputter coater (VG Microtech, West Sussex, England). The specimens were examined with a Philips 505 SEM

Fig 2. (A) Posteroanterior cyst radiograph showing a "figure of eight" radiopaque lesion, located in the sublin- gual and submandibular spaces partially separated by the geniohyoid muscles. (B) Occlusal view cystogram showing that the lesion is limited to the left side of the floor of the mouth.

Fig 4. Light microscopy shows cyst wall consisting of keratinized stratified squamous epithelium, with the presence of sebaceous gland (arrows) and hair follicle (arrowhead) (H&E, original magnification x 28).

58 ZELTSER ET AL

(Eindhoven, the Netherlands) at an accelerating voltage of 20 kV.

Light microscopy showed a cystic structure bounded by a corrugated, keratinized stratified squamous epithelium with the lumen packed with keratin squames. The cystic wall consisted of loose fibrovascular stroma, scattered infiltrated lympho- cytes, and islands of dermal appendages--seba- ceous glands and occasional hair follicles and shafts. Histological examination confirmed the clini- cal diagnosis of dermoid cyst (Fig 4). The SEM

Fig 5. SEM pictures of the dermoid cyst wall consist- ing of epithelial cells arranged in clumps (A); rounded or oblong with smooth or rough surface (ruffleqike struc- tures probably microvillar rudiments (arrowhead) (B); skin appendage-like hair shafts (C). (Bar = 0.1 mm).

Fig 6. One-year follow-up of the case in Fig lC shows normal appearance of the chin-neck profile.

studies indicated the presence of epithelial cells in an unusual arrangement. The cells are either rounded or oblong and arranged in clumps. The cellular surface is either smooth or rough. The rough epithelial cell surface is characterized by a ruffle-like structure associated with microvillar ru- diments. The cyst lumen contains not only keratin, but also fiber-like structures in an irregular configu- ration, possibly collagen fibers.

Below the epithelial cells, there are also the same fiber-like collagen structures in which a hair shaft can be clearly identified (Fig 5). Recovery was usually uneventful, and follow-up for at least one year showed good restoration of appearance and function (Fig 6).

D I S C U S S I O N

The literature usually classifies dermoid cysts according to anatomic site and histologi- cal characteristics. 5.t3

The anatomic classification is based on the relation between the cyst and the muscles of the floor of the mouth. There are basically 3 types. In the median genioglossal or sublin- gual type, the cyst lies above the geniohyoid muscle, displacing the tongue superiorly. In the median geniohyoid or submental type, the cyst is between the geniohyoid and mylohyoid muscle, producing a submental bulge. In a large dermoid cyst, a portion of the cyst may be located superiorly to the geniohyoid and the rest inferiorly, giving the lesion a lobutated appearance (dumbell shape) (Fig 7). The 3rd type, which is rare, is a lateral cyst that lies under the mandible.

Histologically, dermoid cysts can be divided into 3 types: the epidermoid type with the cyst wall lined by simple stratified squamous epi- thelium that may be partially keratinized; the

DERMOID CYSTS OF FLOOR OF THE MOUTH 59

A I- C

Fig 7. Dermoid cyst (DC) located under (A), above (B), and under and above the geniohyoid muscle (C). (1) Geniohyoid muscle. (2) Mylohyoid muscle. (3) Hyoid bone. (Partly taken from CJT Howell: Oral Surg Oral Med Oral Patho159"578-580, 1985).

dermoid type, consisting of an epithelial lin- ing with skin appendages such as sebaceous, sweat glands, and hair follicles in the capsule; and the teratoid type, with an epithelial lining and a fibrous capsule containing skin append- ages, connective tissue, and derivates such as bone, muscle, and respiratory and gastrointes- tinal mucosa.5

SEM studies were initiated to further inves- tigate the unique configuration of the dermoid cyst wall. The epithelial cells are not arranged homogenously in a symmetrical ultrastruc- rural configuration, unlike the epithelium of some other odontogenic cysts. ~4 The ruffle- like structures associated with microvillar ru- diments on the epithelial surface are not found in odontogenic cyst epithelium.

Swelling of the submental area may occur in various conditions, such as dental infection; lymphadenopathy (tuberculosis, cat-scratch disease, sarcoidosis, and infectious mono- nucleosis); neoplastic lesions; benign and ma- lignant salivary gland tumor; cystic hygroma; lymphomas; and lymphangioma and cystic lesions (such as plunging ranula, brachial cyst and thyroglossal duct cyst); and dermoid cyst.

Needle aspiration may be useful in the diagnosis of the above-mentioned lesions. The

dermoid cyst, in particular, shows a typical thick, creamy content.

The injection of contrast medium into the lesion to determine its anatomic limits is of value in the diagnosis of cystic type lesions. Infection of the lesion after injection of the contrast medium did not occur in the 4 cases reported in this article.

The treatment of choice is undoubtedly total enucleation of the lesion. In our view, the intraoral approach is the best, giving a good view of the cyst, easy access, and aesthetic results, even when the cyst is under the genio- hyoid muscle.

A C K N O W L E D G M E N T

We wish to thank Prof. J. Lustmann and Dr E Rahamim for their professional assistance in pro- cessing the tissue material for SEM evaluation.

R E F E R E N C E S

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3. Lindh C, Larsson A' Unusual jaw-bone cysts. J Oral Maxillofac Snrg 48'258-263, 1990

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14. Phil ipsen HP, Chan LSC, Reichart PA, et al: Scan- rang electron microscopy of odontogenic cyst epithelium. JDASA 47:219-223, 1992