7- Cysts of the Jaws

8/13/2019 7- Cysts of the Jaws

1/18

/181

Cysts of the Jaws & oral soft tissues

Classification and incidence of cysts of the jaws: True cyst =pathological cavity lined wholly or in part of it by

epithelium, having fluid or semi-fluid contentswhich

has NOT been created by the accumulation of pus

Pseudocyst =pathologicalcavity that isn't lined byepithelium, having fluid or semi-fluid contentswhich

has NOT been created by the accumulation of pus

Cysts are divided into two main groups depending on the origin of the lining epithelium:1- Odontogenic cysts:

o The epithelial lining is derived from the epithelial residues of the tooth-forming organo Examples of epithelial residues of the tooth-forming organ: reduced enamel epithelium,

epithelial rests of Malassez and epithelial glands of Serres

o 90%of all jaw cysts are of odontogenic origino They can be subdivided according to their etiology (pathogenesis)into:

Developmental cystswhen theres NO specific cause Inflammatory cystswhen theres specific cause which is inflammation

2- Non-odontogenic cysts:o The epithelial lining is derived from sources other than the tooth-forming organ

Classification of cysts of the jaws:1. Epithelial cysts: Odontogenic cysts (90%)

- Developmental Dentigerous (follicular) cyst (10-15%) Eruption cyst Odontogenic keratocyst (3-11%) Lateral periodontal cyst (


2/18

/182

Non-odontogenic cysts (10%)- Developmental Nasopalatine duct (incisive canal) cyst (5-10%) Nasolabial (nasoalveolar) cyst Median cyst

- Pseudocysts (non-epithelialized primary bone cysts) Solitary bone cyst (simple, traumatic, hemorrhagic bone cyst) Aneurysmal bone cyst Stafnes idiopathic bone cavity

2. Cysts of the soft tissues Salivary mucoceles

- Mucous Extravasation cyst-

Mucous retention cyst Dermoid and epidermoid cysts Lymphoepithelial cyst Thyroglossal cyst

There are three kinds of residues that may give rise to odontogenic cysts:1. The epithelial rests or glands of Serres:

o Remnants of the dental laminao Give rise to odontogenic keratocyst& lateral periodontal cyst

2. The reduced enamel epitheliumo Remnants of enamel organand covers the fully formed crown of the un-erupted tootho Give rise to dentigerous & eruption & paradental cysts

3. The rests of Malassezo Remnants of the epithelial root sheath of Hertwigo Give rise to all types of radicular cysts

The locations of different jaw cysts:o The ramus and body of the mandible:

OKC (Odontogenic Keratocyst)o In association with unerupted tooth:

D (Dentigerous cyst)o Periapical location and associated with

heavily carious tooth:

P (Periapical Radicular Cyst)o In the area of extracted tooth:

R (Residual Radicular Cyst)


3/18

/183

o Between the roots of vital mandibular premolars: L (Lateral Periodontal Cyst)

** Could be OKC too but not lateral radicular cyst because the tooth is vital

o Surrounding the crown of the tooth which is about to erupt and still in thealveolar mucosa as a swelling:

E (eruption cyst)o In the gingiva of an adult person:

G (Gingival Cyst) Components of cysts:

o Lumen,which could contain: Degenerating epithelial & inflammatory cells Serum proteins Cholesterol crystals

o Wall:fibrous tissues In OKCthe fibrous wall increases the potential for

recurrence of the cyst

In inflammatory cyststhe fibrous wall is made ofinflammatory infiltrate

o Lining: Which is epithelial tissuethat gives an indications about the originof the cyst (odontogenic,

non-odontogenic)

Radicular cyst: Radicular cysts are epithelialized odontogenic inflammatory cysts Radicular =related to the root portionof the tooth Origin of lining epithelium is odontogenic(epithelial rests of Malassez) Radicular cysts are inflammatory in originbecause necrotic pulp and mediators will go out to

the periapical areainducing periapical periodontitisand then radicular cyst formation

Radicular cysts are subdivided into apical, lateral and residualdepending on the anatomicalrelationship of the cyst to the root of the tooth

Apical radicular cysts:o The most commoncystic lesions in the jawso They are always associated with the apices of (non-vital)

teeth

o They account for about 75% of all radicular cystso When they are small, they are asymptomaticand discovered

incidentally during routine radiographic examination


4/18

/184

o When they are large, they cause expansion of bone(rate of alveolar bone expansion = 5 mm peryear)

- The expansion of the alveolar bone is due todeposition of successive layers of new bone by

overlying periosteum- As the cyst enlarges and causes bone resorption

centrally,increments of new subperiosteal

bone are laid downto maintain integrity of the

cortex, producing a bony hard expansion

- The rate of expansion tends to outstrip therate of subperiosteal deposition, leading to

progressive thinning of the cortexwhich can

be deformed on palpation producing the clinical signs of egg-shell crackling

-

Eventually the cyst may perforate the cortex and present as bluish submucosal swellingo Pain is rare unless there's an acute exacerbationwhich may

rapidly progress into abscess formation

o Radiographically: Present as a round or ovoid radiolucency at the root apex The lesion is often well-circumscribed with or without

peripheral radiopaque (corticated) margin

The cyst develops within an apical granuloma and we can NOTreliably determine from the radiographic featureswhether an apical radiolucency represents a granuloma or cyst

** On average 40% or more of apical Radiolucencies are

cystic

Residual radicular cysts:o Residual cyst =radicular cyst that has remainedin the jaw and

failed to resolvefollowing extraction of the involved tooth

o They account for about 20% of all radicular cystso Radiographically:

Remain in the jaw after extraction and removal of the causativetooth

Lateral radicular cysts:o They account for about 5% of all radicular cysts(very un-

common)

o They arise as a result of extension of inflammation from the pulp into thelateral periodontium along the accessory root canals


5/18

/185

Pathogenesis:o Radicular cysts arise from proliferation of the epithelial rests of Malassez within

chronic periapical granuloma

o NOT all granulomas progress to cystso The environment within the chronically inflamed periapical granuloma (which is likely rich in

cytokines, inflammatory mediators, bacterial endotoxins, growth factorsand others)

stimulates the rests of Malassez to proliferate

o The mechanism of formation of an epithelial-lined cyst cavity within granuloma is unclear, twomain mechanisms have been proposed:

1. Degeneration and death of central cells within a proliferating mass of epithelium- Epithelium is avascular, and transport of metabolites and gaseous exchange occur

by diffusion

- It is argued that when the mass of proliferating epithelium within a granuloma reachesa critical sizethe central cells (furthest away from the surrounding vascular bed)

degenerate and die

- The micro-cyst then forms and continues to expand like a balloon due to the pressure ofthe fluid accumulating inside

2. Degeneration and Liquefactive necrosis of granulation tissue- It is suggested that areas of granulation tissue within the granuloma may

undergo necrosisdue to enclavement by proliferating strands of epitheliumor

to release of toxic productsfrom the dead pulp or from infecting organisms

- Epithelial proliferation to surround such as area of necrosis results in the formation of acyst

Histopathologyo Radicular cysts are lined wholly

or in partby thick non-

keratinized stratified

Sequamousepithelium

supported by a chronically

inflamed fibrous tissuecapsule

o The fibrous capsule is richly vascular and is made of inflammatory infiltrate** This inflammation is present by default(not secondary)

** Thinepithelial lining means no inflammation

** Thinkepithelial lining means heavy inflammationand thus heavy

hyperplasia

o Sometimes radicular cyst surrounds the root apex (pocket cyst)orseparated by a tissue capsule (more common)


6/18

/186

o Metaplasia(change in cell type) of the epithelial liningmay give rise to mucous cells(found in 40% of radicular cysts lining) and more rarely ciliated cells

o In 10% of the cases the lining contains hyalineeosinophilic bodies (Rushton bodies)that appear to

have no clinical significance

** Rushton bodies =hyalinized pinkish bodies present

within the epithelium and they might be products of

epithelium itself (?)

o Deposits of cholesterol crystals cleftsare commonwithin the capsulesof many radicular cysts

** Cholesterol crystals are associated with foreign-body

giant cells

** Cholesterol is probably derived from breakdown of red

blood cells

** Deposits of hemosiderine are commonly associated with

the clefts

o All these finding are non-specific, and they can be presentin the case of Dentigerous cyst too

Cyst contents:o The composition of cyst fluid is complex and variable, and it is hypertoniccompared with

serum and contains:

1. Degenerating epithelial and inflammatory cells2. Serum proteins

** All groups of serum proteins are present in cyst fluid and the soluble protein level is 5-

11 g/dl(higher levels of immune-globulins)and this is what actually makes the cyst

hypertonic and enhances its expansion

3. Water and electrolytes4. Cholesterol crystals(which have a shimmering appearance)

Cyst expansion:o Once formed, radicular cysts continue to expand equally in all directions like a

unicentric balloon

o The majority of radicular cysts don't grow to large dimensionso The rate of cyst expansion is controlled by rate of local bone resorptiono Bone resorption is associated with:

- Activation of osteoclastsby prostaglandins and cytokinesreleased by inflammatory andother cells in the capsule

- Activation of enzyme Collagenaseby interleukin 1 and interleukin 6o As bone is resorbed, the hydrostatic pressureof the contents causes the cyst to enlarge


7/18

/187

o The hydrostatic pressure of the cyst fluid is increased because the contents are hypertoniccompared with serum and then water is drawn into the cyst cavity (through the semi-permeable

membrane or cyst wall) along this osmotic gradient

Management and prognosis:o Treatment of the involved tooth (RCT or extraction)o Surgical enucleation or curettage of the cysto Little or NO tendency for recurrence or neoplastic transformation

Dentigerous cyst (follicular cyst): Dentigerous cyst =cyst that encloses part or allof the crown

of an unerupted tooth

** Dentigerous cyst is intra bony(central cyst)&intra

follicular Dentigerous cyst is the most common epithelialized

odontogenic developmental cyst(10-15% of all

odontogenic cysts and 25% of all jaw cysts)

Origin of lining epithelium is odontogenic(reduced enamelepithelium between the follicle and the tooth crown)

Dentigerous cysts are developmental in originbecause theyhave no specific causebehind their formation

Dentigerous cyst is attached to the CEJand has two main types:- Central typethe cyst completely surrounds the crown of the associated tooth- Lateral typethe cyst projects laterally from the side of the tooth and doesnt completely

enclose the crown of the associated tooth

Dentigerous cyst enlarges by accumulation of fluid between proliferating reduced enamelepithelium and crown of unerupted tooth

Clinical features:o Dentigerous cysts are about twice as common in the mandiblethan in the maxillao Dentigerous cysts most frequently involve teeth that are commonly impactedor erupt lateo The majorityof dentigerous cysts are associated with 3rdmolar, then maxillary permanent

canines, then mandibular premolars

o Uncommonly, dentigerous cysts are associated with supernumerary teeth or with Odontomeso When dentigerous cysts are small, they are asymptomaticand discovered incidentally during

routine radiographic examination

o Pain is rare unless:- Dentigerous cysts are largeand cause expansion of bone- Dentigerous cyst gets infected(secondary infection not by default)


8/18


9/18

/189

o The epithelial lining is supported by a thick fibrous connective tissue wall that is freefrom inflammatory cell infiltration(unless there has been secondary infection) and may

have epithelial rests cells

o Deposits of cholesterol crystals cleftsare commono All these finding are non-specificand they can be present in the case of radicular cyst too

Management and prognosis:o Removal of the affected tootho Surgical enucleation of the cysto Little tendency to recur when completely removed

** Why should the dentigerous cyst be removed?

- Dentigerous cysts can cause extensive bone destruction- Dentigerous cyst can cause resorption of adjacent roots- Dentigerous cysts can cause displacement of teeth- Dentigerous cysts may undergo neoplastic transformationinto either:

Ameloblastoma Sequamous cell carcinoma Central muco epidermoid carcinoma(which is a salivary gland tumor which might

result if mucous cells Metaplasia happened)

Eruption cysts: Eruption cyst = extra-bony dentigerous cyst (peripheral

cyst) = Soft tissue analogue of the dentigerous cyst

Eruption cysts are present as soft, translucent swelling on thealveolar mucosa

Eruption cysts are relatively common in children No treatmentis necessary for such cyst In eruption cysts, hemorrhage into the cyst cavity is

common as a result of trauma (giving the cyst a bluish color)

The lining of eruption cysts may be similar to that of dentigerouscysts BUT is usually modified by chronic inflammation(possibly

due to trauma) and may contain blood(possibly due to traumatoo)


10/18

/1810

Odontogenic keratocysts (Keratinizing cystic odontogenic tumor): Clinical features:

o Odontogenic keratocyst is the second most common epithelialized odontogenicdevelopmental cyst(3-11% of all odontogenic cysts)

o Origin of lining epithelium is odontogenic(epithelial rests or glands of Serres"remnants of dental lamina")

o Odontogenic keratocysts are developmental in originbecause they have no specific causebehind their formation

o About 70-80%of odontogenic keratocysts occur in the body and ascending ramus of themandible (50% of cases occur in 3

rdmolar region)

o In both the mandible and the maxilla the majority of cysts occur in the region posterior to thepremolars

o When odontogenic keratocysts are small, they are asymptomatic (or give rise to few symptoms)and discovered incidentally during routine radiographic examination

o Pain is rare unlessodontogenic keratocyst gets infected(secondary infection not by default)o Unlike radicular and dentigerous cysts which tend to expand in a unicentric ballooning pattern,

odontogenic Keratocysts enlarge predominantly in an anteroposterior direction

(NOT ballooning) and can reach large sizes without causing gross bony expansion

o An important clinical feature of keratocyst is their tendency to recur even after surgicaltreatment

o Odontogenic keratocysts have more growth potential than most other odontogenic cystso The majority of Keratocysts are present as solitary lesions(one lesion only)o Multiple odontogenic Keratocystsare associated with nevoid basal cell carcinoma

syndrome (Gorlin syndrome)

Nevoid Basal Cell Carcinoma Syndrome (NBCCS):o Inherited as an autosomal dominant traito NBCCS is caused by mutation in tumor suppressor gene on chromosome 9q termed

patched gene (PTCH)


11/18

/1811

o Clinical manifestations of Nevoid Basal Cell Carcinoma Syndrome:a. Skin:

- Multiple nevoid basal cell carcinomas(in about 90% of cases) that might occuranywhereand commonly appear around the age of puberty

**Typical basal cell carcinomas occur on sun-exposed skin in adults

- Hyperkeratosis of palms and soles

- Cysts and benign tumors of skinb. Oral:

- Multiple Odontogenic keratocyst(in about 90% of the cases) that might occurthrough-out the lifetimeof the patient but tend to appear earlier than single

odontogenic keratocysts not associated with NBCCS

c. Skeletal:- Rib abnormalities- Vertebral deformities- Cleft lip and palate

d. CNS:- Calcified falx cerebriand brain tumors

e. Ophthalmologic:- Hypertelorism


12/18

/1812

o Treatment and Prognosis: Nevoid basal cell carcinomas are treated by Mohs surgery Odontogenic keratocysts are surgically removed Usually have normal lifespan

Radiographic features:o Present as a unilocular or multilocular radiolucency

o The lesion is often well-circumscribedwith peripheral radiopaque (corticated)margin

o Can present like dentigerous cystin association with unerupted tooth (in 25%-40% of cases)

o Can present like lateral periodontal cyst

oo

o Can displace teeth, roots, and perforate cortical plate Microscopic features:

o Epithelial lining: Odontogenic keratocysts are lined by thin and

folded layer of keratinized stratified

Sequamous epithelium(6-10 cells thick,

uniform thickness, corrugated surface)** Thin epithelial lining means no inflammation


13/18

/1813

** Parakeratosis predominates(nucleated

keratinocytes)

** Cells desquamate into the cyst lumen

Polarization of basal cell nuclei High mitotic activity

** Mitotic activity in this cyst is higher than

any other odontogenic cyst and so many mitotic figures are foundin basal and supra-

basal cells

If the odontogenic keratocyst becomes secondarily infectedthen the epithelial liningloses its characteristic histology and becomes similar to the lining of

radicular cyst

Radicular and dentigerous cysts may rarely produce keratin (by Metaplasia)but their epithelial lining is usually orthokeratinizedand doesnt show the regular andordered epithelial differentiation that characterize the odontogenic keratocyst

** Odontogenic keratocyst must not be used to describe any cyst producing keratin such as

radicular and dentigerous cysts

o Fibrous capsule: Thin & free from inflammatory cell infiltration & have low tensile strength

** The fibrous wall of odontogenic keratocyst is thin and has low rupture strength relative to that

of the radicular cyst and this makes enucleation (surgical removal) of odontogenic

keratocysts more difficultand recurrence may thus follow retention offragments of the torn wall and lining

Contains daughter cysts Small groups of epithelial cells are often found in

the capsule and these can give rise to independent

daughter cysts around the main lesion

Retention of daughter cysts when the mainlesion is enucleatedis one of the factors associated

with the high recurrencerate of keratocyst

More daughter cysts are found in nevoidBasal Cell Carcinoma syndrome

o Lumen: Odontogenic keratocysts contain white cheesy material consisting of keratinous

debris

Little free fluid Odontogenic Keratocysts have low soluble protein level less than 4 g/dl composed

predominantly of albumin


14/18

/1814

Growth of the odontogenic keratocyst:o Growth of odontogenic keratocysts is predominantly in anterio posterior direction(not

equally in all directions in a unicentric ballooning pattern)

o Growth of odontogenic keratocysts is NOT due to osmotic pressure(since growth isn'tequal in all directions but more in the anteroposterior direction)

o Odontogenic keratocyst has aggressive pattern of growthand that's why ithas beenproposed that this lesion is named the keratinizing cystic odontogenic tumor

o Factors involved in growth and enlargement of odontogenic keratocysts:1. Active epithelial growth Epithelial lining of odontogenic keratocyst shows higher rate of mitotic activity

than other odontogenic cysts

Epithelial proliferation is NOT uniformbut tends to occur in clustersprojecting andfolding into surrounding Cancellous bony spaces in a multicentric pattern of

growth(not unicentric)

Abnormalities in the expression of some of the key proteins controllingthe cell proliferation cycle similar to that seen in neoplasia

The proliferative activity and altered expression of cell cycle related proteins of theepithelial lining is higher in odontogenic keratocysts associated with the

Nevoid Basal Cell Carcinoma syndrome2. Cellular activity in the connective tissue capsule Active growth of the capsule occurs in association with the proliferating areas of the

epithelium

Osteoclasts tend to be located around the tips of the projections of the lining which areproliferating into the Cancellous spaces

3. Production of bone resorbing factors Like the radicular cyst, odontogenic keratocyst releases bone resorbing factors

including: Prostaglandins, Interleukin 1, Interleukin 6 and Collagenase enzyme

In comparison to radicular cysts, odontogenic keratocysts have less bone resorbingactivity.However, it is likely that this is the result of the focal rather than uniformpattern of growth activity of the cyst wall

The aggressive behavior of odontogenic keratocysts indicates that they secrete moreinterleukin 1than radicular or dentigerous cysts

4. Intracystic pressure Increase in Intracystic pressure is due to:

a. Hypertonic nature of the contents of odontogenic keratocystsb. Accumulation of Sequamous debris within the lumen

Increase in Intracystic pressure is unlikely to be a significant factor in cystexpansion,and would not account for the biological behavior of the lesion


15/18

/1815

Why does OKC show high recurrence rate?o Epithelial buddingand daughter (satellite) cystformationo Relatively thin fibrous capsuleo Thin friable epitheliumo Biological quality of the cyst epithelium

Management and prognosis:o Surgical excision

Peripheral ostectomy, Carnoy solution, intracystic Carnoy solution injection, decompressionfirst

o Recurrence rate of 30%(3-60%)o Most recur within 5 years, and others may not recur until 10 years or more and this necessitates

the long term clinical and radiographic follow upo Occasionally, local resection and bone graftingo If multiple Odontogenic Keratocysts are present, evaluate the patient for nevoid basal

cell carcinoma syndrome

Differential diagnosis for odontogenic Keratocysts radiographically includes:1. Dentigerous cysts(associated with unerupted 3rdmolars)2. Developmental lateral periodontal cysts3. Ameloblastoma4. Glandular odontogenic cyst

Orthokeratinized Odontogenic Cyst It accounts for 7-17% of all keratinizing jaw cysts It is NOT a specific type of odontogenic cysts It was previously considered as orthokeratinized variant of OKC Histopathological features:

o Orthokeratinized odontogenic cysts are lined by keratinizedstratified Sequamous epithelium

** Orthokeratinization predominates(nuclei-free

keratinocytes)o Orthokeratinized odontogenic cysts do NOT have the characteristic lining of

Odontogenic Keratocysts

o Treatment and Prognosis:o Surgical enucleation and curettageo Recurrence is rare(around 2%)o Orthokeratinized odontogenic cysts have No association with nevoid basal cell carcinoma syndrome


16/18

/1816

Lateral periodontal cyst: Lateral periodontal cyst is the uncommon epithelialized odontogenic developmental

cyst(less than 2% of all odontogenic cysts)

Origin of lining epithelium is odontogenic(epithelial rests or glands of Serres"remnants of dental lamina")

Lateral periodontal cysts are developmental in originbecause they have no specific causebehind their formation

Pathogenesis:o Lateral periodontal cysts are derived from the post-functional dental lamina and they have

limited growth potential

Clinical Features:o Lateral periodontal cysts are asymptomaticmost of the time and discovered incidentally

during routine radiographic examination

o 75-80% of lateral periodontal cysts occur in premolar-canine-lateral incisor areao Lateral periodontal cysts occur in Mandible > Maxillao Lateral periodontal cyst is located on the lateral surface of a tooth that is vital

Radiographically:o Present as a well defined radiolucencythat is relatively small(less

than 1 cm in diameter)

o Present as a unilocular or multilocular radiolucency(whenpresent as multilocular radiolucency they are described as "botryoid

odontogenic cyst"because of their resemblance to a bunch of grapes)

o Radiographic features are not diagnostic Differential diagnosis for lateral periodontal cyst

radiographically includes:

1.Odontogenic keratocyst2.Lateral radicular cyst (associated with non-vital tooth)

Histologically:o The lateral periodontal cysts are lined by thin non-

keratinized Sequamous epithelium

** Thin epithelial lining means no inflammation

o Lateral periodontal cyst has plaque-like thickening Treatment and prognosis:

o Surgical excision or curettageo Preserve dentitiono Recurrence is infrequento Botryoid is different


17/18

/1817

Gingival cyst Gingival cysts are uncommon epithelialized odontogenic developmental cysts Origin of lining epithelium is odontogenic Odontogenic keratocysts are developmental in originbecause they have no specific cause

behind their formation

Gingival cysts are of little clinical significance Gingival cysts are common in neonateswhen they are often referred to as (Bohns nodule or

Epsteins pearls)

Gingival cysts of neonates are similar to epidermoid cystsinhistopathology (epithelium and keratin only)

Gingival cysts of adults are similar to lateral periodontalcystsin histopathology

Most gingival cysts disappear spontaneously by 3months of age

Paradental cyst Paradental cysts are epithelialized odontogenic inflammatory cysts Origin of lining epithelium is odontogenic(reduced enamel

epithelium)

Paradental cysts are inflammatory in originand arise becauseof extension of inflammation into the reduced enamel epithelium

inducing cystic changes

Teeth associated with paradental cysts may show cervical enamelextension

Paradental cyst arises alongside a partially erupted molarinvolved by pericoronitis

Almost, all paradental cysts occur in the mandibleand most ofthem are buccally or distobuccally located

Radiographically:o Present as a well defined radiolucency related to the

neck of the tooth and the coronal third of the root

Histopathologically:o Inflammatory paradental cysts resemble inflammatory radicular cysts

Glandular odontogenic cyst: Glandular odontogenic cysts are uncommon epithelialized odontogenic developmental

cysts

Origin of lining epithelium is odontogenic


18/18

/1818

Odontogenic keratocysts are developmental in originbecause they have no specific causebehind their formation

Clinical Features:o Strong predilection for the anterior portion of the jaws, especially the mandibleo Variable sizeo Pain or paresthesia

Radiographically:o Present as unilocular or multilocular

radiolucency

Histologically:o Glandular odontogenic cysts have a lining with

glandular structure

Prognosis:o Glandular odontogenic cysts have aggressive locally

invasive nature and a tendency to recur

Date post:	04-Jun-2018
Category:	Documents
Upload:	prince-ahmed
View:	226 times
Download:	1 times

7- Cysts of the Jaws

Documents