Diagnosis Of Cysts InThe Oral Cavity

Regions

By:SASHI KUMAR MANOHARCRIDepartment Of Oral Medicine & RadiologyVMSDC

Definition

A Cyst is a pathologic cavity having fluid, semi fluid or gaseous content and which is not created by accumulation of pus.

Most cysts, but not all, are lined by epithelium. (KRAMER 1974)

Types Of Cysts

TRUE CYSTS :

Cysts which are lined by epithelium, E.g. Dentigerous Cyst, Radicular Cyst, etc.

PSEUDO CYSTS : Cysts which are not lined by

epithelium, E.g. Solitary Bone Cyst, Aneurismal Bone Cyst, etc.

Parts Of A Cyst

A Cyst has the following parts:

1. Wall 2.Lumen Of Cyst 3.Epithelial Lining

Classification

CYSTS OF THE ORAL REGION

EPITHELIAL LINED

DEVELOPMENTAL

ODONTOGENICNON

ODONTOGENIC

INFLAMMATORY

NON EPITHELIAL LINED

EPITHELIAL-LINED CYSTS

DEVELOPMENTAL ORIGIN i) Odontogenic a) Dentigerous cyst b) Odontogenic Keratocyst c) Lateral Periodontal Cyst d) Gingival cyst

ii) Non-Odontogenic a) Globulomaxillary cyst b) Nasolabial cyst c) Median Palatal cyst

INFLAMMATORY ORIGIN a) Radicular cyst b) Residual cyst c) Paradental cyst

NON-EPITHELIAL LINED CYSTS

a) Solitary Bone Cyst b) Aneurysmal Bone Cyst c) Traumatic Bone Cyst

Frequency Of Epithelial Cysts Of Oral Region

(SHEAR 2006)

52.30%

18.10%

11.60%

8%

5.60%

4.20% SHEAR 2006 Radicular cyst

Dentigerous cyst

Odontogenic keratocyst

Residual cyst

Paradental cyst

Unclassified odontogenic cysts

Criteria For Diagnosis

Based On Clinical Features Based On Anatomical Site Of Jaw Based On Histological Features Based On Aspirate Fluid Based On Radiographic Features

Based On Clinical Features Small cysts are usually symptomatic Large cysts exhibits large swelling and

pain Irregularity of teeth-missing tooth,

impacted tooth, supernumerary tooth, displacement of tooth, non vital tooth, carious tooth, etc

Presence of fluctuation in the swelling upon palpation

Condition of the bone plate-bulging and thinning over the outer cortical bone plate

Based On Anatomical Site Of Jaw Mandibular regions: -3rd molar regions, canine regions-

common impacted tooth regions- Dentigerous Cyst

-angle of mandible, ascending ramus of mandible regions- Odontogenic Keratocyst

-Premolar and molar regions-Lateral Periodontal Membrane- Lateral Periodontal Cyst

-solitary bone cyst and aneursymal bone cyst occurs only in the mandible

Maxillary regions-canine and 3rd molar regions

impacted canines and 3rd molars-Dentigerous Cyst

Based On Histological Features

Sample specimens stained with Eosin & Hemotoxylin stains

Dentigerous Cyst

Dentigerous cysts exhibts two types with variant histologic features

Inflammed Type Non-Inflammed Type

Inflammed Type

Lining shows varying degrees of hyperplasia with rete ridges and occasionally even keratinization.

Wall is composed of mature connective tissue which shows infiltration by chronic inflammatory cells

Focal areas of mucous cells can be seen in the lining. Small odontogenic epithelial islands can be seen in the wall.

Non-Inflammed Type

Lining derived from reduced dental epithelium, consists of 2-4 cell layers of non keratinized epithelium, without

rete ridges.

Wall composed of thin fibrous connective tissue appearing immature, as it is derived from the dental papilla.

NON INFLAMED dentigerous cyst showing a thin nonkeratinized epithelial lining

INFLAMED DENTIGEROUS CYST showing a thicker epitheliallining with hyperplastic rete ridges. The fibrous cyst capsule shows a diffuse chronic inflammatory infiltrate

Periapical Cyst

Cholesterol crystals in from of clefts are often seen in the connective tissue wall, inciting a foreign body giant cell reaction

Originate from disintegrating RBC’s in presence of inflammation

Different types of dystrophic calcification are also seen in connective tissue wall.

Mucus cell metaplasia as well as respiratory cells may be seen in the epithelial lining.

Keratinization if found is due to metaplasia and must not be confused with an OKC.

Quiescent epithelium lining a mature, long-standing periapical cyst

Mucous cells in the surface layer of the stratified squamous epithelial lining of a periapical cyst

Mural nodule of cholesterol-containing granulation tissue fungating into the cavity of a radicular cyst

Odontogenic Keratoyst (OKC)

The epithelial lining is composed of a uniform layer of stratified squamous epithelium,usually six to eight cells in thickness

The epithelium and connective tissue interface is usually flat, and rete ridge formation is inconspicuous.

The basal cell layer has columnar / cuboidal cells with reversely polarized nuclei, imparting a “picket fence” or “tombstone” appearance

The luminal surface shows flattened parakeratotic epithelial cells, which exhibit a wavy or corrugated appearance

Small satellite cysts, cords, or islands of odontogenic epithelium may be seen within the fibrous wall

Epithelial lining is 6 to 8 cells thick, with a hyperchromatic and palisaded basal cell layer

Note the corrugated parakeratotic surface

Satellite microcysts in the wall of an odontogenic keratocyst that appear to be arising direct from an active dental

lamina

Based On Aspirate Fluid

1.Dentigerous Cyst →Clear, pale, straw coloured fluid,

rich in cholesterol crystals

2.Odontogenic Keratocyst →Creamy white, cheese like material, thick aspirate

3.Infected Cyst →Yellowish, foul smelling fluid, pus

discharge

4. Aneurysmal Bone Cyst →Blood on aspiration

5.Solid Tumor Mass →Negative aspiration

Based On Radiographic Features

Various radiographic methods that are used are:

Intra-Oral Periapical Radiography Occlusal Radiography Orthopantomogram CT scan

Radiographic Features Of Cysts

DENTIGEROUS CYST -

Unilocular or occasionally multilocular well-defined, radiolucency with sclerotic margins

3 types - Central Type - Lateral Type - Circumferential Type

Central Type

Lateral Type

Circumferential Type

(a) (b)Figure (a) shows two types of dentigerous cyst The one on the right is lateral typeThe one on the left is circumferential type

Figure (b) shows central type of dentigerous cyst. Appreciate the resorption of the root of the first mandibular molar

PERIAPICAL CYST

Round, ovoid radiolucency with thin sclerotic borders and usually associated with pulpally affected tooth

Loss of lamina dura at the apex of the tooth root

Figure shows well defined radiolucency associated with the apex of a non-vital root filled tooth.

Odontogenic Keratocyst

Unilocular or multilocular well defined radiolucent area with smooth and scalloped radiopaque margins

(a) (b) (c)

Figure (a)shows a small OKC lesionWith scalloped border

Figure (b)shows a larger OKC lesionWith scalloped border

Figure (c)shows a larger multilocular OKC lesionWith scalloped border

Figure shows an OKC lesion that has envelopedAn unerupted tooth to produce a “DENTIGEROUS” appearance

Common Epithelial Cysts Of Oral Region

Dentigerous Cyst Periapical Cyst Odontogenic Keratocyst

Dentigerous Cyst

The dentigerous cyst is defined as a cyst that originates

by the separation of the follicle from around the crown of an unerupted tooth

It develops by accumulation of fluid between the

reduced enamel epithelium and the tooth crownThe dentigerous cyst encloses the crown of an unerupted tooth and is attached to the tooth at the cementoenamel junction

Etiology

Reduced Enamel Epithelium

Dentigerous cyst arises from accumulation of fluid between the reduced enamel epithelium and the tooth crown

Clinical Features

AGE : 1st to 3rd decades.

GENDER : More frequently in males than in females.

SITE : 2/3rd associated with unerupted mandibular 3rdmolar Maxillary canine Mandibular premolar Maxillary 3rd Molar Supernumerary tooth also can be involved

Sign & Symptoms

Most cysts grow to a large size before being discovered while observing a dental x ray to detect the cause of an unerupted tooth.

Large lesions can cause cortical expansion, leading to facial asymmetry, teeth displacement, root resorption, even pain, if infected.

Gross Specimens

Multiple gross specimens of Dentigerous Cyst

Notice the cystic lesionencloses the crown of the tooth and is attached to itscementoenamel junction

Differential Diagnosis

Although dentigerous cysts present a unique feature, but some lesions must be considered in its differential diagnosis :

1. Unicystic ameloblastoma2. Adenomatoid odontogenic tumor.

Complications

Recurrence due to incomplete surgical removal.

Development of ameloblastoma either from lining epithelium or from odontogenic islands in the connective tissue wall.

Development of squamous cell carcinoma either from lining epithelium or from odontogenic islands in the connective tissue wall.

Development of mucoepidermoid carcinoma from mucus secreting cells in the lining.

Periapical Cyst

Synonyms : Radicular cyst Apical Periodontal cyst

Periapical cysts are the most common inflammatory cysts

They arise from the epithelial residues in the periodontal ligament as a result of periapical periodontitis following death and necrosis of the pulp.

Etiology

Periapical cysts usually arises at the apical end of a carious tooth, they arise from the epithelial residues in the periodontal ligament

Carious infection followed by slow necrosis of the pulpal tissues of the tooth

Death of pulpal tissues results in formation of granulation tissue at the apical end of the tooth root

Lession develops to cyst following periapical periodontitis

Clinical Features

Age: 3rd, 4th and 5th decades

Sex: Slightly frequent more in males

Site: Maxillary anterior region and mandibular anterior regions

Frequency: Most common inflammatory cystic lesion of the oral region

Signs & Symptoms

Primarily asymptomatic Usually associated carious tooth and non vital

tooth

Discovered during routine dental X ray exam while

examining a carious tooth

Slowly enlarging hard bony swelling initially. Later, if cysts breaks through cortical plates, lesion becomes fluctuant

Rare in deciduous teeth

Odontogenic Keratocyst (OKC)

OKC’s arises from cell rests of the dental lamina.

They exhibit a different growth mechanism and biologic behavior from the more common dentigerous cyst and radicular cyst.

Several investigations suggest that odontogenic keratocysts

can be regarded as benign cystic neoplasms rather than cysts

Etiology

cell rests of serres (dental lamina)

OKC arises from Islands of epithelial cells that

originate from the oral epithelium and remain in the tissue after inducing tooth development.

Clinical Features

AGE: Occurs over a wide age range and cases have been recorded as early as the first decade and as late as

the ninth In most series there has been a pronounced peak

frequency in the second and third decades

GENDER: More frequently in males than in females

SITE: The mandible is involved far more frequently than the maxilla

50% cases occur in angle region and extending to the ascending ramus and forwards to body of mandible

Signs & Symptoms

Pain, swelling or discharge seen Occasionally, paraesthesia of the lower lip or

teeth. Some are unaware of the lesions until they develop pathological fractures

In many instances, patients are remarkably free of symptoms until the cysts have reached a large size, involving the maxillary sinus and the entire ascending ramus, including the condylar and coronoid processes

occurs because the OKC tends to extend in the medullary cavity and clinically observable expansion of the bone occurs late.

Gross Specimens

Gross specimens of eneucleatedOdontogenic Keratocyst (OKC)

Differential Diagnosis

In case of unilocular radiolucency– Dentigerous cyst, Eruption cyst,Unicystic ameloblastoma etc.

In case of multilocular radiolucencies – Conventional ameloblastoma, Central giant cell granuloma, Aneurysmal

bone cyst etc.

Complications

Malignant transformation of cyst lining rare, but has been reported.

High rate of recurrence

Reasons for recurrence :

1. Thin, fragile lining is very difficult to remove completely.

2. New cysts develop from satellite cysts left behind.

3. New cysts can also develop from basal cells of overlying oral epithelium, especially in ramus – 3rd molar region.

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