Odontogenic tumor 2 l Oral pathology MCQs

 

Tumor of Odontogenic Tissue Origin ; cementoblastoma , odontogenic myxoma and fibroma , ameloblastic fibro-odontome (describing histopathology , radiographically and treatment of each tumor)  l oral pathology MCQ for dental students

ODONTOGENIC TUMORS

AMELOBLASTOMA

• Most common Odontogenic epithelial tumor
• Arise from remnants of dental lamina, reduced enamel epithelium , rest of Malassez, basal cell layer overlying surface epithelium
• locally invasive, but does not metastasize.

Common (Follicular, Polycystic) Ameloblastoma.

•  Posterior mandible and ascending ramus
• Most common type
• Characteristic feature: "Eggshell crackling" because ameloblastoma can expand the bony cortices, but due to their slow growth the periosteum can produce a thin shell of bone .
• X-ray of  Ameloblastoma   : Multilocular radiolucency or soap bubble appearance

Histopathology of Ameloblastoma :

• Epithelial processes composed of well-organized single layer of Ameloblast-like cells with "Reversed polarity" which surround loosely arranged polyhedral or angular cells resembling stellate reticulum.

Histologic patterns are:

• Follicular Pattern:
• Most prevalent, resembling the earlier stages of tooth development.
• Palisaded ameloblast-like cells with reversed polarity + centrally a stellate reticulum-like cells + microcysts.
• Plexiform Pattern:
• Epithelium in "fishnet" or mesh arrangement.
• Acanthomatous Pattern:
• Central epithelial cells transform into squamous cells that produce keratin within individual cells or in the form of keratin pearls.
• Granular cell Pattern:
• sheets of large eosinophilic granular cells.
• Basal cell Pattern:
• darkly stained cells with little evidence of palisading at periphery.
• They have mistaken for basal cell carcinoma.
• Desmoblastic Pattern:
• The epithelial component is widely separated by fibrous tissue that is dense & scar-like.
• has a mixed radiolucent/radiopaque radiographic  appearance that resembles Fibro-osseus lesions
• It is more difficult to treat, because it penetrates the surrounding bone trabeculae & remains undetected.
• [These histological variants do not affect tumor behavior]

Unicystic Ameloblastoma:

• large unilocular cyst commonly associated with the crown of an impacted tooth [ mostly with a severely displaced mandibular third molar]

 X-ray of Unicystic Ameloblastoma :

• unilocular radiolucency with well-demarcation & even corticated

Three histological variants:

1. Luminal Unicystic Ameloblastoma: fibrous C.T capsule surrounding a large fluid-filled lumen + cytoplasmic vacuolization.
2. Intraluminal Unicystic Ameloblastoma:One or more nodules of ameloblastoma project from cyst lining to the lumen mostly of plexiform type
3. Intramural Unicystic Ameloblastoma: The fibrous cyst wall is infiltrated by typical follicular or plexiform ameloblastoma

Peripheral Ameloblastoma [ least common]

• Rare, Limited to the soft tissue of the posterior gingiva
• Resemble Pyogenic granuloma or fibroma
• Radiographically = Only superficial saucerization of the cortical plate.
• Treatment of all Ameloblatsomas : Local excision to Block resection

Adenomatoid odontogenic tumor (AOT)

• Originates from reduced enamel epithelium

Radiographically:

• Unilocular radiolucency with well-corticated borders that surround the crown of impacted tooth (cuspid), like dentigerous cyst & the difference between them are:

1. Radiolucency extends apically beyond CEJ.
2. The presence of flecks of radiopacities (snowflake).

Microscopic picture Adenomatoid odontogenic tumor (AOT)

1. Epithelia in ductal like patterns [microcysts resembling duct cut in cross section (they are not
2. Ducts & are never seen cut longitudinally) lined by cells similar to ameloblasts.
3. Spherical calcification

• Treatment: ENUCLEATION

CALCIFYING EPETHELIAL ODONTOGENIC TUMOR (PINDBORG TUMOR) CEOT

• Originats from dental lamina A/O REE
• could be mistaken for a poorly differentiated carcinoma.
• Affects posterior body of the mandible

Histopathology of  CALCIFYING EPETHELIAL ODONTOGENIC TUMOR (PINDBORG TUMOR) CEOT =

• squamous & clear cells that
• spherical calcification
• amyloid staining & hyaline deposits
• lack of stromal inflammatory reaction
• Concentric spherical calcifications ( Liese-gang ring calcifications) **
• It differs from ameloblastoma by:

1. epithelial cells do not resemble ameloblasts.
2. contains spherical diffuse calcification

 

Radiographically of  calcifying epethelial odontogenic tumor (pindborg tumor) ceot:

• uni or multi locular radiolucency with scalloped margins with flecks of calcified structure around crown of impacted mandibular molar

Differential Diagnosis:

• Dentigerous cyst
• Adenomatoid odontogenic tumor
• Ameloblastic Fibroodontoma

Treatment: resection including a margin of normal tissue

Calcifying odontogenic cyst/ tumor ( GHOST CELL CYST)

• Contains "ghost cells" & "Spherical calcification"
• It affects mostly areas anterior to the first molar

Radiographically GHOST CELL CYST:

• Unilocular radiolucency containing flecks of indistinct radiopacities + Associated with unerupted tooth (mostly canine)

Histopathology of GHOST CELL CYST =

• Outer layer of palisaded cells & an inner layer of stellate reticulum
• Enlarged eosinophilic keratinized , epithelial cells without visible nuclei "ghost cells" within the stellate reticulum + multiple calcifications

Treatment GHOST CELL CYST:

• Enucleation for cystic lesion
• More aggressive treatments for solid lesion

SQUAMOUS ODONTOGENIC TUMOR

• anterior to the molars of either jaw
• Triangular Unilocular radiolucency close to the roots of erupted teeth.

Treatment :

• curettage and extraction of involved tooth
• Local curettage & exo of involved tooth.
• usually misdiagnosed as ameloblastoma, resulting in unnecessary radical surgery.

Squamous odontogenic tumor

• Anterior to the molars of either jaw
• Triangular unilocular radiolucency close to the roots of erupted teeth.

Treatment of Squamous odontogenic tumor:

1. Curettage and extraction of involved tooth
2. Local curettage & exo of involved tooth.
3. Usually misdiagnosed as ameloblastoma, resulting in unnecessary radical surgery.

 

Ameloblastic fibroma

• True biphasic tumor
• May represent the early developing stage of ameloblastoma

X-ray of ameloblastic fibroma:

• Unilocular or multilocular radiolucency with impacted tooth in mandibular or maxillary molar area

Histopathology of ameloblastic fibroma

• Odontogenic epithelia resembelling dental lamina & the cap & bell stages of early odontogenesis. 
• Zones of hyalinization are often surrounding the epithelial component of the lesion.” Juxtaepithelial’’

Treatment of ameloblastic fibroma

• Enucleation [lesion is well-encapsulated & easily separated from the surrounding]
• Recurrence is high due to inadequate initial removal of what are frequently multilocular lesions

 

Ameloblastic fibro-odontoma

Radiographically ameloblastic fibro-odontoma

• Well- circumscribed uni or multilocular radiolucency  with variable amount of calcification with unerupted tooth

Histopathology ameloblastic fibro-odontoma  :

• General features of ameloblastic fibroma but contains enamel & dentin matrix . More calcified lesions show mature dental structures ( as rudimentary tooth or conglomerate masses of enamel and dentin)

Treatment: curettage            

Odontogenic myxoma

• Derived from embryonic c.t ( ectomesenchyme)

Radiographically odontogenic myxoma:

• Multilocular radiolucency with "soap bubble" or "honey comb" pattern.
• The radiolucent defect may contain thin, wispy trabeculae of residual bone which often arranged at right angles to one another

Histopathology odontogenic myxoma:

1. Widely separated spindle or angular-shaped cells against a background of mucoid, ground substance.
2. In the periphery, the myxomatous tissue penetrates the bone →difficulty in removing the lesion.
3. Misdiagnosed histologically with: chondromyxoid fibroma or, myxoid neurofibroma

Treatment:

1. Small myxoma → curretage with careful periodic evaluation
2. Large myxoma → block resection,
3. Because of the gelatinous nature of the lesion, it is important to remove an intact specimen to reduce the chance of recurrence.

 

CEMENTOBLASTOMA

• Cementum-like tissue growing in continuity with the apical layer of a molar or premolar that produces expansion of cortical plates & pain [ diagnostic feature]
• Molar/premolar area of mandible with lesions attached to the apical 1/3 of the vital root.

Radiographically of CEMENTOBLASTOMA

1. Unilocular well-demarcated radiolucency or mixed radiolucent/radiopaque or completely radiopaque
2. Root resorption.

Histopathology CEMENTOBLASTOMA

• Unmineralized cementum matrix that are continuous with the normal cementum layer of the tooth roots.
• Periodontal ligament follows the bulbous periphery of the lesion.
• Reversal lines which is indicate extensive remodeling during growth of the lesion.
• Central region has mngc

Treatment : enucleation