lecture 8, cysts of the jaws 2 (script)

8/3/2019 Lecture 8, Cysts of the Jaws 2 (script)

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Oral Pathology (1) 8th lecture >

Dr. Rima Safadi

Just a quick advice before we start, make sure to read the slides

when you are studying as not all information in the slides werementioned in the lecture.

The doctor started this lecture by telling us that she reviewed the

absent lists manually by her own to solve the problems that occurred

due to the old and new seating numbers lists, and everything is ok

now, and the absents are corrected according to the last seating

numbers list, and that the absents are on the E-learning now, so you

should not have any further complains!!!, another point the doctoremphasized was that she dont use her office which is on the 10Hs

and her office is on the deanship, and she will be there every Sunday

and Wednesday afternoon from 1:30 pm to 4:30 pm in the dean

assistance office which located in the D1 the floor level, another

thing about the absents excuses is that whatever your excuse was

you should get it signed from the dean even if it was just simple as I

had overslept, you should write it and get it signed from the dean!!!

And if it was a medical excuse you should get it signed by themedical committees and by the dean, in order to accept it.

Now lets start our lecture, the slides for this lecture are under the

title Cysts Of The Jaws 2, as the doctor explain the first few

slides in the last lecture she went over them in a bit of hurry.

Slides No. (1-16) >>> Overall of OKC

Last time we stopped with the OKC, I will continue calling it OKC

because it was its name Odontogenic Keratocyst, but now it iscalled Keratinizing cystic odontogenic tumor as the WHO want to call

it now, they changed its classification from the cysts to the tumors,

as it is now worse than before, why the OKC is worse than others?

The Odontogenic Keratocyst is characterized by several features not

present in other cysts, the cyst has high recurrence rate; from 30%

to 60% of all OKCs show recurrence, it is possible that the recurrence

occurs even after 5 years or 10 years, and it is not necessarily to

happen after the first year of treatment, so because of that thediagnosis of OKC is important, when I diagnose a cyst as OKC this is

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significant to the patient, because the patient has to follow us closely

and yearly, not only for one year, but for years because it may show

recurrence, we said that there is

histopathologic features that are

characteristic to the OKC like the

columnar basal cell layer, uniformthickness, ribbon like epithelium,

sometimes separation between the

epithelium and the underlying

connective tissue, and most of the

times Para-keratenization, and we

said all of this in the last lecture.

In addition to that we have daughter cysts, the epithelium has a high

proliferative potential, so it will proliferate giving buds inside theconnective tissue capsule and later on daughter cysts will start

forming, so that if the surgeon treated the cyst incompletely, there

will be a cyst after that, it will return, because there is a daughter

cyst here that will proliferate and come back again.

Now what are the features of the epithelium that makes it highly

proliferative?

First of all it is mitotically active, that means there is a lot of

proliferation or a lot of mitotic cells, that means the number of cells

increased quickly, in addition to loss of some of the factors that

control the cell cycle, do you know what does the cell cycle control

mean? It means that the cell cant proliferate forever, we have

controls on the rate of the proliferation, here there is a problem with

the controlling factors over the cell cycles in addition to the high

mitotic rate, and this makes the epithelium mitotically active, that

means if the surgeon leave a small piece of epithelium it will

proliferate and introduce a cyst later on in addition to the cysts here,

now another feature of the epithelium is that it proliferates not

uniformly, not all the epithelium proliferate at the same rate, it

proliferates focally; that means it is focally active and for this reason

the expansion of the cyst is multi-focal, it goes within the marrow of

the cancillous bone, where ever there is a proliferation in different

spots, sometimes it give us a multi-locular appearance because it

has a multi-focal proliferative potential or locations of the epithelium

itself, and this is what relates to epithelium, now what about what

relates to the connective tissue? The connective tissue capsule is

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different than the other cysts, it is usually lacking the tensile

strength, it does not stretch, it rapidly get ruptured, so as it lacks the

tensile potential, it may rupture easily, and if it ruptured easily then

the total removal of the cyst will be difficult, so we have features of

OKC in the epithelium and in the connective tissue itself that

increase the recurrence potential rate of this type of the cystincluding daughter cysts formation. The best location of the OKC is

the posterior part of the mandible angle (photo.1) see the next

page - and ramus of the mandible (photo.2), it can be uni-locular or it

can be associated with impacted tooth (photo.3), it can be between

tow roots (photo.4) like the lateral periodontal cyst, it can be multi-

locular, it can be located like the naso-palatine duct cyst which we

will talk about in a few minutes, between the roots of the maxillary

incisors (photo.5), because here we have the naso-palatine duct orthe naso-palatine canal, and in the naso-palatine canal there was the

naso-palatine duct, later on in the development the naso-palatine

duct disintegrated and it gives a remnants of epithelium and these

remnants later on may give us a naso-palatine duct cyst, but this

finally turned to be OKC, how did we make sure that it was an OKC?

By the histopathologic diagnosis, because it has a characteristic

features, and here (photo.3) it looks like the dentigerous cyst but it is

big.

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Growth of the OKC we talked about it and we also talked about the

factors that are involved in the active epithelium growth.

Slide No.17 >>> Odontogenic Keratocyst Growth

Now about the connective tissue capsule we said that it has a little

tensile strength, in addition to that there is active growth of the

capsule according to the proliferative epithelium, and this means

that the epithelium is focally proliferating, andin the focal areas of the proliferative epithelium there is active

growth of the capsule, it goes with it; that means if the capsule did

not do a proliferation with the epithelium then there will be rupture

of the cyst, there is no growth within the bone, there is no folding

within the bone, so there is focal active growth also in the connective

tissue at the areas of the epithelium, the osteoclasts will start

resorbing the surrounding bone just in the areas of the proliferation

or in the proliferative areas, there will be focal or local production ofinterleukin 1, interleukin 6, prostaglandin and collagenase, do you

remember these factors as we talked about them when we talked

about the radicular cyst, and we said that they are stimulated by

inflammation, but here we dont have inflammation, they are focally

produced by the cells or the local cells, so these factors induce bone

resorbtion increasing the expansion of the cyst, now what is the

main direction of expansion? It is mainly anterio-posterior.

The Intra cystic pressure actually has a big question mark, becausethere is a little fluid inside the cyst, and the contents of the cyst are

mainly cheesy like material; something white color; which is keratin,

the cyst mainly contains keratin and a little fluid, so the osmotic

pressure actually is not a factor, it has a very little contribution

compared to the other growth factors, for this reason; due to the

changes in the cell cycle control factors, due to the high mitotic rate

and due to the other factors this cyst now is list with the odontogenic

tumors.

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Slide No.18 >>> Odontogenic Keratocyst >>> Management

and Prognosis

The management and prognosis, the surgical excision, the peripheral

ostectomy, now we dont want to do a enucleation, the simple

enucleation doesnt work in this cyst, this cyst should be

aggressively treated to be sure that there will be no recurrence, or todecrease the rate of the recurrence.

Here the doctor write some notes that are not in the book like; after

they do a surgical removal they put a Carnoy solution inside the

cavity that the cyst was in previously; to kill or minify the remnants

of the epithelium, and his is not required; you will take it in surgery.

Slide No.19 >>>Odontogenic Keratocyst >>>Reasons of

Having High Recurrence RateNow why does OKC show high recurrence rate? We have just said

them;

1) Epithelial budding and satellite cyst formation.

2) Relatively thin fibrous capsule.

3) Thin friable epithelium, we notice that the thickness of the

epithelium is thin and continuous; it is from 6 to 10 cell layers, and

sometimes we notice a separation below the epithelium, so it can be

slot easily.4) Biologic quality of the cyst epithelium; which is the mitotic rate

and the cell cycle control changes.

Slide No.20 >>> Odontogenic Keratocyst >>> Management

and Prognosis

Now if your patient is having multiple Odontogenic Keratocysts you

should think about a syndrome called nevoid basal cell carcinoma

syndrome, what is this syndrome? It is autosomal dominant, it has a

mutation in the tumor suppresser genes called PTCH, tumor

suppresser gene.

Slide No.21 >>> Nevoid Basal Cell Carcinoma Syndrome

What do we have in this

cyst? In this syndrome

we have oral features

including multiple OKCs,

here (Slide No.22) wehave two of them clearly

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seen, but the others are not clear, so we have multiple odontogenic

keratocysts.

Now about the skin features, the patient has

multiple basal cell carcinomas, starting at early

age, you know that in basal cell carcinoma the

sun exposure is a factor, but here may be there is

no sun exposure, may be the patient is young but

he will have multiple basal cell carcinomas.

Like this patient here (Slide No.23).

Also they have hypertelorism which means

increase in the inter-pupillary distance, and this is

also one of the features.

See here (Slide No.24) the basal cell carcinoma,

the treatment of it is by Mohs surgery the doctor

is not sure if it is written in the book or not; it is

done as they remove the basal cell carcinoma;

the lesion, but they dont remove a big safemargin, because we have several basal cell carcinomas, and that

means the whole faces skin may be removed; so they start

removing a little safe margin then they send it to the pathology lab

for frozen section, and they ask for immediate response; is the

margin free or not, and if it is not they remove a little bit more and

ask for a response, and if it is not then they remove a little bit more

again, but they cant remove a big save margin (1), so they should

be careful when treat the basal cell carcinomas.Look here (Slide No.25) it may occur in areas that are not really

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exposed to the sun (2), but it happened because there is a problem

in the tumor suppresser gene, and here

(Slide No.26) there are bits on the skin and may be skin tumors

also (3).

Slide No.27 >>> Odontogenic Keratocyst In Basal Cell Nevus

Syndrome

Odontogenic Keratocyst syndromic cysts have the same

histopathologic features as any other odontogenic Keratocyst non-

syndromic cysts, which are uniform thickness, para-keratin on the

surface, corrugated surface,

separation from the under laying

tissue, ribbon like appearance of the

cyst, you should memorize these

features as your names.

Slide No.28

The falx cerebri is calcified, this white

thing here; calcification in the falx

cerebri.

Slide No.29 >>> Basal Cell Nevus Syndrome

Now we talked about the treatment before, but the lifespan is that

the patient lives normally,

and it does not affect the lifespan of the patient.

Slides No.30+31 >>>

Orthokeratinized Odontogenic

Cyst

Now suppose that we have these

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features which are typical of OKC and also we have an ortho-keratin

not para-keratin, can we change the diagnosis? Or should we change

the diagnosis? No, because ortho or para keratin it doesnt matter,

what is important that we have the histopathologic features of the

epithelial lining, because these cells are the cells which have a

biologic activity that allows them to proliferate, and not the type ofthe keratin that affect.

Now suppose we have ortho-keratin, but we have simple lining, like

this (Slide No.45~Cysts Of The Jaws 1), a cyst that have this

simple lining, no hyper chromatic columnar cells, no palisading, no

ribbon like appearance, but there was keratin, will you call it OKC?

No.

So what should we call it? instead of calling it odontogenic

keratocyst keratocyst is the important word here we should call itodontogenic cyst, but we add a descriptive term in the beginning, we

say keratinizing odontogenic cyst, it is a regular odontogenic cyst,

and it is not characteristic or a specific type, it is just an odontogenic

cyst, but it is keratinizing, and this is how we know that it is not an

OKC, but if you saw the word keratocyst it means OKC or the tumor

variant of it, so keratin with normal lining or with a non-specific lining

will be keratinizing odontogenic cyst, and we will see it in a few

minutes.

Slide No.32 >>> Orthokeratinized Odontogenic Cyst >>>

Management and Prognosis

Now why should I tell the clinician? Is it important to know if it is a

keratinizing odontogenic cyst or an OKC? Yes, it is important, but

why? Because the keratinizing odontogenic cyst has a very low

recurrence rate 2% compared with 60% of the OKC, the keratinizing

odontogenic cyst does not requiredaggressive treatment or extensive follow

up, while OKC requires aggressive

treatment and follow up.

And this is an example (Slide No.31),

this is a cyst lining, it is epithelium, and I

cant see the columnar basal cell layer

which is hyper chromatic, and I cant see

any palisaded, but here in the lumen we have keratin the red colorand this type is called ortho-keratin, because I dont see pecnotic

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nucleoli, so keratin with non-specific lining is called keratinizing

odontogenic cyst or ortho-keratinized odontogenic cyst, but mainly it

is called keratinizing odontogenic cyst, and we said what is its

significant.

Slide No.33 >>> QuestionsNow the question is: suppose that the OKC was secondarily inflamed,

the inflammation comes from the adjacent tooth, what will happen to

the histopathologic features? Will they still be characteristic? No, the

inflammation affects the specific histopathologic features, because

inflammation induce hyperplasia in the epithelium, so there will be

no more thin lining or separation from the underlying connective

tissue, even the basal layer become hyper plastic and we will lose

the characteristic features of the OKC if there was inflammation.

Slides No.34+35+36 >>> Lateral Periodontal Cyst

Another developmental cyst, as we said the OKC is a developmental

cyst and it is a non-inflammatory cyst arising from the remnants of

the dental lamina, the dentigerous cyst is a developmental

odontogenic cyst arising from the reduced enamel epithelium, now

also from the dental lamina there is a cyst called the lateral

periodontal cyst, and it is called lateral because it occurs on the

lateral aspect of the root, and it is called periodontal because it

occurs in the periodontal space, and it is called cyst because it has

an epithelial lining and it is a cyst.

Slide No.37 >>> A Radiograph

Now let us look at the radiograph to understand

the terminology, so it is lateral because it is

lateral to both teeth in this case, and periodontal

because it occurs between the teeth and sometimes in the periodontal space, and cyst because

it is cystic, now this cyst although it originates

from the dental lamina remnants like the OKC,

but this is a simple, small cyst and does not

show a recurrence and does not grow in big sizes

and it doesnt need aggressive treatment and it

enters in the differential diagnosis of the OKC

and lateral radicular cyst; because it looks like both of them.

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Slide No.38 >>> Lateral Periodontal Cyst >>>

Histopathologic Features

Now do we need the tooth to be necrotic or non-vital to have this

cyst?

No, actually this cyst usually occurs with vital teeth, but it is possible

for coincidence to find this cyst with a non-vital tooth, but when Itake it to the histopathology examination it may turn to be lateral

periodontal cyst and not lateral radicular cyst, this means that not

every cyst associated with a non-vital tooth should be radicular or

inflammatory, it may be lateral periodontal cyst, if we take it to the

microscopic examination we see differences in the thickness of the

epithelial lining.

Slide No.39Here we have very thin lining

relatively thin lining 1 and then

we have thick plaques 2, thick

layers or thick areas of the lining,

then you do back to thin lining 3,

then all the sudden it is thick 4, we

dont see this feature in OKC, in

OKC there is uniform thickness, so this feature distinguish the lateralperiodontal cyst, and there are lots of glycogen within the

epithelium, this means that in the thick areas the cytoplasm of the

epithelium contains glycogen, so it looks pale, thin 1 ~ thick 2 ~ thin

3 ~ thick 4, so this is a lateral periodontal cyst.


The most common location for the lateral

periodontal cyst is in the mandibular

premolar area, it is well defined radiolucency,

small ~ less than 1 cm, and it does not need

an aggressive treatment or any other thing.


Another example of the lateral periodontal cyst,

although there is a filling here.

Slide No.42+43 >>> Lateral Periodontal

Cyst >>>

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Management and prognosis, simple surgical removal,

occasionally it could be

multi-locular, but they call it botryoid, just like the grapes looks like,

and that is why it is called occasionally multi-locular, and if it is

multi-locular radio graphically, then we need some curettage of the

area; to prevent the recurrence.

Slide No.44 >>> Gingival Cyst of The Adult

Now do you remember the dentigerous cyst? We said that it is

completely present within the bone, it is central, and we said that

when the tooth

erupts, the cyst will

be called eruption

cyst; because itis going to erupt,

now the lateral

periodontal cyst is

also inside the bone,

not outside; that means it is not in the gingiva, but we may have a

similar cyst that is located in the gingiva, in the soft tissue, so now it

is no longer bony, so now we call it gingival cyst of the adult, why do

I say of the adult? Because there is a gingival cyst of the new born,so usually we dont say just gingival cyst and stop there, we say

either gingival cyst of the adult or gingival cyst of the new born,

depends where it appears or presents.

Now this is the sac and here (1) is the cyst, it is presented within the

soft tissue, there is no bone here, and this here (2) is a normal

epithelium, surface epithelium, this whole biopsy is taken from the

gingiva.

Slide No.45 >>> QuestionsFor now we have talked about OKC, lateral periodontal cyst, gingival

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tissue

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cyst of the adult and the dentigerous cyst, and these 4 cysts are

developmental cysts.

Now what is the most common developmental cyst between

them?

It is the dentigerous cyst.

Which one of them has the highest recurrence rate?It is the OKC.

What is the cyst that was put with the tumors now?

It is the OKC.

Now among all the cysts that you have heard about, what is

the cyst that should be associated with a non-vital tooth?

It is the radicular cyst, which is an inflammatory cyst.

Now we will move to other slides with the title OdontogenicCysts 3 and 4

Slide No.1 >>> Paradental Cyst

Now we have another inflammatory cyst which is called paradental

cyst, now how many inflammatory cysts we have talked about until

now? This one is the second one, and all the others were

developmental cysts, the paradental cyst is an

inflammatory cyst that occurs on one side of a

partially erupted tooth, because of that we have

inflammation here, because the tooth is partially

erupted, there is a communication with the oral

cavity and bacteria enters between the tooth and

the surrounding soft tissue, then the inflammation

occurs, and then proliferation of the remnants of

reduced enamel epithelium which are present at the side of the

tooth and it is partially covering the

unerupted tooth, as we said this is a partially erupted tooth, and its

crown is covered with the reduced enamel epithelium, and the

partially erupted tooth with the remnants of the reduced enamel

epithelium, if it gets stimulated with an inflammation it may

proliferate, now why some teeth will have a paradental cysts and

others dont (not all the teeth have a paradental cyst), now some of

the teeth which are completely erupted or fully erupted may have

paradental cyst, why? As it is fully erupted from where the

inflammation will come? The cause here is that the tooth may have a

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the developmental changes we said that the enamel may occur in an

abnormal location; like enamel pearl and the cervical enamel

extension, it goes downward from the crown to the root surface, and

we said that the significance of it is that there will be lost of the PDL

attachment; so a pocket will be formed, and then the bacteria will

enter, and an inflammation will occur, then there will be aproliferation of the epithelium and finally a cyst formation, occurring

in any root surface where a cervical enamel extension is present, the

histology is just like the radicular cyst, but it is an inflammatory cyst,

and there may be a rushton bodies, or cholesterol clefts, and we may

see also hyperplastic epithelium due to the inflammation, and there

may be a mucous metaplasia.

Slides No.2+3+4 >>> Glandular Odontogenic CystNow we will start with another new developmental cyst which is

called the glandular odontogenic cyst, and it is called glandular

because it acts like a gland or a gland-like structures in the lining,

and this gland-like structures are

mucous cells, see this empty cells

here (Slide No.3), they are mucous

cells, and this thing here is a mucus

material or a water-like materialwhich is inside the cells, and these

cells here are mucous cells, and

when the mucous cell aggregate or

accumulate, they give us a gland-

like appearance, and that is why they call it a glandular cyst, but it is

a glandular odontogenic cyst, because these mucous cell came from

metaplasia of the odontogenic epithelium, so it is called a glandular

odontogenic cyst.Now does it have specific features? Yes, it has a characteristic

location and it has a special clinical behavior, the location of it is or

it prefers to present in the anterior part of the mandible, it may be

multi-locular,

and also it has a relatively higher recurrence rate, now this cyst is

the second one which has a high recurrence rate, and the first one or

the main one or lets say the boss of them is the OKC, now as the

glandular odontogenic cyst also may show a high recurrence rate, soit needs an aggressive surgical removal, curettage and so on.

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Also it has a strong predilection to the anterior part of the jaws,

especially in the mandible, and it comes with pain or paresthesia

some times; now when the paresthesia occurs? When it makes a

compression or a pressure on the nerve, especially the mental nerve

which is present here or its branches.

And about the prognosis we said that it is potentially aggressive,locally invasive and it has a tendency to re-occur, so it needs a

slightly aggressive treatment.

Slide No.5 >>> Non-odontogenic Cysts of The Jaw

Now we have finished the cysts which have an odontogenic lining,

where its lining epithelium is from odontogenic origin, now we will

start with the cysts which have a lining which is non-odontogenic.

Slide No.6 >>> Naso-palatine Duct Cyst (Incisive Canal Cyst)

We talked a little bit about the naso-palatine duct or the naso-

palatine canal, in the embryo the naso-palatine canal were

containing the naso-palatine duct, and later on the naso-palatine

duct will disintegrate leaving remnants, what else do we have as you

took in the anatomy course? What else does the naso-palatine canal

contain? What exits from it and enters the oral cavity?

The naso-palatine nerve, the naso-palatine artery, the remnants of

the duct as it disintegrated and disappeared and the neurovascular

bundle; that means we have a vein, nerve and an artery, that enters

this canal and goes down toward the oral cavity.

Now this naso-palatine canal end with

the incisive papilla intra-orally, which is

located between the roots of the central

incisors, the naso-palatine duct cyst is

possible to be anywhere along the naso-

palatine canal, it may occur intra-orally

in the soft tissue; like in the incisive

papilla and then we will call it the cyst of

the incisive papilla, or the cyst could be

anywhere along the naso-palatine canal,

it may be here in the bone, or it may goes a little bit above or more;

like between the nose and the oral cavity.

Slide No.7 >>> Naso-palatine Duct Cyst (Incisive Canal Cyst)>>> Clinical Features

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It is non-odontogenic cyst, and intra-orally it may present as a

swelling and it may drain pus if it was secondarily inflamed.

The naso-palatine duct cyst is a non-odontogenic cyst, it is a true

cyst and it is a developmental cyst; that means it occurs by itself

without a previous warning, and the cause is idiopathic, there are no

predisposing factors for the developmental cysts, and no one candetermine whether to have an OKC or not, or to have a noso-palatine

duct cyst or not, there are no predisposing factors for this cyst.

In the naso-palatine duct cyst they say that there may be a trauma

or an inflammation and etc., but in general it is a non-inflammatory

cyst.

It may happen with a vital or a non-vital teeth; it does not matter,

unlike the radicular cysts.

Slide No.8 >>> Cyst of the Incisive Papilla (Cyst of Papilla

Palatina)

We said about the cyst of the incisive papilla that it is a soft tissue

cyst.

Now how many cysts we talked about and it occurs in the bone, and

at the same time has a soft tissue counterpart? Go and revise it.

>>> may be there are 3 of them, but Im not sure.

Slide No.9 >>>Nasopalatine Duct Cyst (Incisive Canal

Cyst)>>>Radiographic Features

Now lets look to this radio graph (Slide No.10) photo.1, here we

have a heart-shaped

radio-lucency presents at the mid line of the maxilla, also here

(Slide No.11) photo.2, there is an inverted heart shaped radio-

lucency; because we have here the nasal spine, which will be super

imposed over it, so that will give us the heart shaped, and in the mid

line between the roots of the central incisors it may push the central

incisors roots and cause a displacement of them, and it may induce a

root resorption, because it is chronic which means a continuous

pressure here.

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Slide No.12>>>Naso-palatine Duct Cyst (Incisive CanalCyst)>>>Microscopic Features

Before we start talking about the microscopically features of the

naso-palatine duct cyst, what do you expect the lining of the nasal

cavity and the maxillary sinus to be? What is their type?

It is ciliated pseudo stratified columnar cells, so the lining of the

naso-palatine duct cyst may contain ciliated pseudo stratified

columnar cells or squamous epithelial cells, or mucous metaplasia, it

is like a mixture of the lining epithelium which could present there.Also as the naso-palatine canal contains a neurovascular bundle, so

that we may find a prominent neurovascular bundles in the cyst wall,

so when they remove it and send it to do the biopsy tests in the lab

we may find a big or a prominent neurovascular bundles.

Slide No.13 >>> Naso-palatine Duct Cyst

Here you can see a mucous cells and a ciliated pseudo stratified

columnar cells.

Slide No.14 >>> The Concept of The Median Cysts

In the book they wrote a little bit about the median cysts, previously

they were saying that there is a median cyst that occurs in the mid

line of the palate and it is separate than the other cysts, but actually

now it turned to be that the median cyst is just a descriptive term of

a cyst which can be a naso-palatine duct cyst or an OKC or a

radicular cyst or it can be any other odontogenic cyst, this means

that we dont have a separate cyst which is called the median cyst,

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the median cyst is now a description of any cyst that occurs in the

mid line of the palate.

Slide No.15 >>> Extra-osseous Developmental Cysts >>>

The Naso-labial Cyst

Now we almost finished the bony cysts; there is a one more bonycyst.

Any way lets now talk about the soft tissue cysts, which are cysts

that occurs in the soft tissue, as we talked about canals, and we

talked about the naso-palatine duct remnants, we also have a naso-

lacrimal duct remnants, when the person gets tears inside his eyes,

where will some of the tears go?

To the nasal cavity; as you took in the anatomy we have an opening

of the

naso-lacrimal duct within the nasal cavity, and the theory here is

that there may be a displacement of this naso-lacrimal duct during

the development or during the embryogenesis, so it goes out of the

nose or a remnants of this duct

remained outside the nasal cavity, so

later on a developmental cyst may occur

and develop from the remnants of the

naso-lacrimal duct, and this swelling in

the soft tissue here between the nose

and the lip and on the lateral aspect of

the nose is called a naso-labial cyst.

Is it true cyst or pseudo cyst?

Do you know what is the difference between the true and the pseudo

cysts?

IT is that the true cyst has an epithelial lining, and the pseudo cyst

does not have an epithelial lining.

So the naso-labial cyst is a true cyst; because it has an epithelial

lining which comes from the naso-lacrimal duct remnants.

Now every duct is lined be epithelium, the ducts of the minor

salivary glands, the naso-lacrimal and the naso-palatine ducts.

Any duct is lined be epithelium, so when we say remnants of the

naso-palatine or the naso-lacrimal this means that we have an

epithelial lining.

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Slide No.16 >>> Non-epithelial (Pseudo cysts) of The Jaws

The pseudo cysts that occurs in the jaws, we have more than one

cyst named pseudo cyst that is occurring within the jaws bone.

Slide No.18 >>> The Trauma-hemorrhage Theory

Now before we talk about these pseudo cysts we have the trauma-hemorrhage theory, some times when the patient or a child get a

trauma to the mandible a box for example, what will happen?

May be there will be a bleeding and a hemorrhage within the bone

inside the bone, now if there is a clot formation or coagulation of

the hemorrhage after the clot formation there will be an organization

of the clot and bone may form again and then the cavity will be

closed or the bleeding will disappeare, and this is the normal

situation or how the healing occurs in any organ, like if you have askin cut or an injury, then there will be clots on the surface and then

the clot later on will go on an organization and it will transform to

other type of tissues, so if hemorrhage occurs within the bone and a

clot was form and organization of the thrombus or the clot occurs,

this may end up without a cavity.

Now if hemorrhage occur and disintegration of the thrombus occurs

and the clot is gone, we will end up with a cavity an empty cavity,

and this is one end, the best is to have organization of the thrombusand bone formation, then we may have a cavity and the other

extreme is that the hemorrhage will be accumulated within the

cavity, and the blood gets accumulated within the cavity without an

endothelial lining not like blood vessels it just get accumulated and

it is surrounded by a connective tissue.

Slide No.17 >>> Solitary Bone Cyst

Now if the cavity is empty we call it solitary bone cyst, which is also

called traumatic bone cyst, simple bone cyst and idiopathic bone

cyst, it is an empty cavity containing nothing or very little amount of

a connective tissue, and it occurs more in children; because they say

that it is following the trauma-hemorrhage theory which is more in

children and adolescence, and it may cause a bone expansion.

There was only one case interesting that Dr.Rima faced before, it

was very obvious case of solitary bone cyst occurring in the ramus of

the mandible causing bone expansion for a teenager, which has a

significant expansion, but the other solitary bone cysts were without

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So 25% of the solitary bone cyst causes bone expansion, and it is

mostly in the molar region.

Slides No.19+20 >>> Radiographic Features + Treatment

and Prognosis

Also it has a characteristic feature which is the scalloping betweenthe roots, it goes up and down between the roots, and as we said it

follows the trauma-hemorrhage

theory, it is rarely multi-locular,

and sometimes we need a surgical

intervention, but why? Why some

times this will not heal unless we

perforate the cyst?

To induce another hemorrhage sothat a thrombus may form and

organization may occur and the cyst may close.

And also to establish the diagnosis; if we were suspecting with

another thing.

Slide No.21 >>> Aneurysmal Bone Cyst

The aneurysmal bone cyst is what? What we have just said about it?

The aneurysmal bone cyst is the cyst which is on the other extreme

of the trauma-hemorrhage theory; as we said its either we have a

closure or an empty cavity or a collection of hemorrhage or blood

within the cavity or within the connective tissue, and this is called

the aneurysmal bone cyst, it may be rapidly expanding,

and it may cause a gross disfigurement of the patient as it cause an

expansion rapidly and it contains a lot of blood, so if it is perforated

it may bleed heavily, it occurs mostly in the posterior part of the

mandible, it may be occur alone by itself due to a trauma or it may

occur in an association with other lesions, this means that it could be

a primary or a secondary, the other lesions are like the giant cell

granuloma or like the fibro-osseous lesions, and you will take these

things later on when we talk about the bone lesions.

Slide No.22 >>> Aneurysmal Bone Cyst >>> The

Pathogenesis

The pathogenesis for it is controversial or uncertain, the trauma-

hemorrhage theory again, or the haemodynamic disturbance.

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See how it looks multi-locular, and the bone is expanding (see the

arrows), and the pressure is too

much; as it causes some times an

external root resorbtion associated

with it, other than the displacement ofthe teeth.

So when the lesion is rapidly growing

it will resorb the teeth, and there is no

time for the teeth to be displaced,

when the lesion is chronic, or over a

long periods of time the roots may be displaced and it may be

resorbed.

Slide No.24 >>> Aneurysmal Bone Cyst >>> Microscopic

Features

Microscopically we have pools of blood surrounded by multi-

nucleated giant cells, and I did not say surrounded by endothelial

lining, because if you go back to the definition of the blood vessels or

the capillaries you will find that the capillaries and the blood vessels

are lined by endothelial cells, but here we dont have an endothelial

lining, so these are not true blood vessels, they are justaccumulation.

Slides No.25+26+27 >>> Lingual Bone Defect

Do you remember the lingual bone defect? That one we have taken

before, it is called the Stafne bone defect, it occurs below the ID

canal, and also we talked about the lingual bone defect that is

possible to occur in the anterior part of the mandible, so go back to

the developmental changes for these two lesions, but here because

of the cysts we will say that these are not true cysts, these are

concavities in the lingual aspect of the bone.

Slide No.28>Cysts of the Soft Tissue>The Salivary

Mucocele>Extravasation mucocele

We still have a little things to talk about, we have what is called the

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Pools of saliva 2*


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salivary mucoceles, now as you took previously in the anatomy and

the histology; the salivary glands are lobules and ducts that exits

from it, and in the oral cavity there are a lot of minor salivary glands

with ducts that open in the inside of the oral cavity, the labial

mucosa, the lower labial or the whole labial mucosa.

Now where there are no salivary glands or minor salivary glands inthe oral cavity?

In the anterior part of the hard palate, on the gingiva, the anterior

tow thirds of the dorsum of the tongue; because posteriorly there are

the Von Ebners glands.

But any other location like the lateral border of the tongue or the

ventral surface of the tongue, the floor of the mouth, the upper and

the lower labial mucosa, the buccal mucosa and the soft palate, it

contains minor salivary glands.A trauma to the minor salivary glands, the lower lip which is

supposed to trauma very much like box for example, what will

happen to the lower lip?

One of the complications is to have a leakage of saliva from the

minor salivary glands, we have two cases either we may have a

leakage out of the duct or we may have accumulation of the saliva

within the duct, now look to this photo (Slide No.29),

here we have a duct photo.1, and we said that the ducts are lined

with epithelium, and suppose that we have saliva accumulation here,

so we have fluid, and now we will have a fluid lined in a cavity that is

lined by epithelium, so this is a cyst; there is a fluid and a cavity

lined by epithelium, so here we have a cyst, and in this case we will

call it a retention mucocele, the retention mucocele is a true cyst; it

has a lining epithelium, but when the saliva goes out of the duct

photo.2, a rupture of the duct or the salivary gland lobules occur,here in the center we have a cavity, and we have a wall, but we

dont have an epithelial lining, because all the saliva goes out of the

duct see the 2* arrow, and we dont have an epithelial lining, so we

call it pseudo cyst.

So we have pseudo cysts and we have a true cysts in the mucoceles,

the true cyst is called the retention mucocele, where the saliva is

retained inside the duct,

and the extravasation mucocele is a pseudo cyst, where there is noepithelium, and the saliva leaked out of the duct and it is

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1 2


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accumulating within the connective tissue, and as the saliva is a

foreign body; the body will try to localize it by granulation tissue, so

here we have a granulation tissues surrounding the pools of saliva;

the saliva appears as a pools or accumulations, so the pools of saliva

are surrounded by granulation tissues without epithelial lining.

What do we see in this wall?We see fibroblasts, blood vessels and a lot of inflammatory cells;

mainly macrophages, the macrophages here are coming to engulf

the saliva, to induce a healing of the area, so we have here

macrophages which are engulfing the saliva.

So the extravasation mucocele is not lined by epithelium, and the

retention type is lined by epithelium, most of the mucoceles occurs

in the lower lip, and most of the mucoceles are extravasation type.

Now how do they appear clinically?They appear bluish; because they contain fluid, so they give us a

bluish translucent submucosal swelling, and usually the patient gives

us a history of a trauma, and they fluctuate in size, sometimes the

saliva leaks and increase the size of the mucoceles, and sometimes

there is decreased, maybe we can say that the lower lip is swollen,

but it may be increased or decreased inside, and this is the fluctuant

size.

Slide No.30>>>Cysts of the Soft Tissues>>Salivary

Mucocele>>>Retention Mucocele

The retention we said that it is lined by ductal epithelium.

Why there is no inflammatory reaction in the retention mucocele?

Because the saliva is still inside the duct, it does not go out of the

duct or the saliva did not leak to induce an inflammatory reaction, it

is still contained within the duct.

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*** As you may be confused now, the salivary mucoceles which we

talked about till now are of two types:Type 1 is the extravasation mucocele which 70% of its cases occur in

the lower lip.


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There were a question by a student which I couldnt hear, but here is

the doctors answer: the retention mucocele has more than one

cause, it could be traumatic and it could be due to a stone in the

duct; may be a stone will close the duct, so all the saliva will be

accumulating in the other part or the posterior part of the duct, so it

will cause the retention mucocele.

Slide No.31 >>> Ranula

Ranula is a mucocele that occurs in the floor of the mouth, maybe it

is mainly from the sublingual salivary gland, a trauma to the

sublingual salivary gland may leak saliva in the floor of the mouth

inducing an extravasation type of mucocele.

What is the plunging ranula?

It is a ranula occurring in the floor of the mouth that goes throughthe mylohyoid muscle and present extra orally, and you know we

dont like these things to be in the floor of the mouth; because it will

cause an elevation to the tongue, it may have an effect vocally or it

may affect the larynx, or it may affect the are ways; and that is why

it is called the plunging ranula.

Slide No.32 >>> Ranula >>> Clinical Photo

And here is an example, it didnt leak

through the mylohyoid muscle, it

presents intra orally as a ranula,

which is a swelling, bluish translucent

in the floor of the mouth, from the

sublingual salivary gland, and actually

it is from the extravasation type. The same appearance of it may be

seen in another cyst which is called the dermoid cyst.

Slide No.33 >>> Dermoid and Epidermoid CystsThe mucoceles when subjected to pressure or palpation it has fluid-

cells, while when doing a palpation for the dermoid cyst it does not

have fluid-cells, so what does the dermoid cyst contain?

It contains epithelial cells, but before that lets answer this question;

what is the different between the dermoid cyst and teratoma? What

is teratoma?

Teratoma is a tumor which has two aspects a benign and a

malignant.Do you hear before about someone with a hair cyst? And where does

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it occur most of the times?

It occurs mainly in the mid line of the back; because the mid line of

the body is the area where the three layers of the embryo; the

ectoderm, the mesoderm and the endoderm meet and fuse, now the

floor of the mouth is a mid line, so we may have dermoid cysts and

we may have teratoma in the floor of the mouth.The dermoid cyst does not contain all products of the three germ

layers; it may have two of them, where the teratoma contains

products of the three germ layers.

In the teratoma we may find teeth, but in the dermoid cyst we may

find epithelium and hair and may be other contents or components,

but not teeth and other products like the intestine, but we may have

it in the teratoma.

So the dermoid cyst is a developmental lesion, which occurs usuallyin the mid line of the oral cavity or in the mid line of the back, and

maybe there is entrapment of the epithelium in the mid line, it is

lined by ortho-keratinized epithelium, it contains keratin, and it also

contains a skin appendages; which means the things that appears or

emerges from the skin; like the hair and the sebaceous glands which

are associated with the hair.

Now suppose that we dont have hair, but we have only a squamous

epithelial lining of this cyst, so what should we call it?

In this case we call it epidermoid cyst, where the cyst is lined only by

epithelium and it is not containing hair appendages, but when it is

containing hair appendages we call it dermoid cysts.

You should know how to distinguish between the dermoid cyst and

the epidermoid cyst.

Slides No.34+35+36 >>> Lymphoepithelial Cyst

The last soft tissue cysts we will take about today are thelymphoepithelial cyst, we talked about these cyst in the

developmental changes, as we said that we have oral

lymphoepithelial cyst; because we have a lot of lymphoid tissue in

the oral cavity, and again the locations that contains a lot of

lymphoid tissue are the lateral border of the tongue, the soft plate,

the floor of the mouth, in addition to

other locations.

Here the lymphoid tissue may haveentrapped epithelium, the

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epithelium may enters these lymphoid tissue, and this epithelium

may proliferate later on, and it may form a cavity lined by epithelium

and surrounded by a wall of lymphoid tissue, it is called lympho

because the wall is lymphoid, epithelial because the lining is

epithelium, and cyst because it is a cyst.

Now what does it contain?It contains sloughed epithelium +/- keratin and products of the lining

epithelium.

What are the locations?

The soft palate and the lateral tongue.

How does it look clinically?

It looks as a small soft swelling which is yellowish in color.

What is these black dots here (Slide No.36)?

They are lymphocytes, this is a lymphoid tissue, it seems like thesame structure as the lymph node, and also we have germinal

centers here.

If this cyst occurs extra orally; in the neck, we call it cervical

lymphoepithelial cyst, which has a characteristic location; anterior to

the sterno-cleiodo-mastoid muscle, but here we dont have a

mucosa.

So here from where dose the lymphoid tissue come from?It comes from the lymph nodes.

And from where the epithelium came?

May be it is a remnants of the branchial arches or traumatic

displacement of the epithelium, because of a trauma the patient had

during the development, the epithelium may enter the lymph nodes

causing a developmental cyst called the lymphoepithelial cyst.

So the lymphoepithelial cyst either it is cervical or intra orally it has

the same histopathologic appearance, the lymphoid tissue, there is acavity lined by epithelium and containing sloughed epithelium or

keratin.

But the pathogenesis is different, here in the cervical

lymphoepithelial cyst it could be from branchial arches remnants

and there in the intra orally lymphoepithelial cyst it is just

displacement of the epithelium in the underlying lymphoid tissue.

Slide No.37 >>> Thyroglossal Cyst

The thyroglossal cyst, we talked about it before in the developmental

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The End

Im really sorry for being late, but it is Eid.

I wish you all get high marks in your exams.

Done by : Raja Amin El-haddad.

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lecture 8, cysts of the jaws 2 (script)

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