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Dx:Ameloblastic Fibro-odontoma

KEY FACTS

Terminology

Ameloblastic fibro-odontoma (AFO)Definition: Mixed ectodermal-mesenchymal tumor similar to ameloblastic fibroma but with scattered collectionsof enamel and dentin

Imaging

Well-defined, sometimes corticated, lucent area with specks of tooth-density materialwithin

Calcifications may bedoughnut-shaped with rim of enamel density

Associated with missing tooth or unerupted tooth

Most common inposterior mandiblepericoronal to developing tooth

May appear as small as enlarged tooth follicles or few cm in diameter

Larger lesions have more calcified material

CBCT will show buccolingual expansion

Top Differential Diagnoses

Ameloblastic fibroma

Odontoma

Adenomatoid odontogenic tumor

Calcifying cystic odontogenic tumor

Calcifying epithelial odontogenic tumor

Pathology

Islands of odontogenic epithelium in loose primitive connective tissue resembling dental papilla

Clinical Issues

Age: 2nd decade

M = F

Large lesions may present as painless bony swelling

Treatment: Enucleation, recurrence rare

Development of ameloblastic fibrosarcoma after curettage has been reported but is very rare

TERMINOLOGY

Abbreviations

Ameloblastic fibro-odontoma (AFO)

Definitions

Mixed ectodermal-mesenchymal tumor similar to ameloblastic fibroma but with scattered collections of enameland dentin

IMAGING

General Features

Best diagnostic clue: Largely radiolucent area with specks of tooth density materialwithin it associated withmissing tooth or tooth that has not erupted

Location: Most common in posterior mandible occlusal or pericoronal to developing tooth

Size: May appear as small as enlarged tooth follicles or a few cm in diameter

MorphologyWell defined

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May or may not be corticatedMixed density internal structure but mostly radiolucentLarger lesions have more calcified materialCalcifications may bedoughnut-shapedwith rim of enamel densityCalcifications do not resemble teethUnilocular; rarely multilocular

Imaging Recommendations

Best imaging toolCBCT will show buccolingual expansion if present and relationship of related tooth to vital structures (inferioralveolar nerve canal or maxillary sinus)Periapical or panoramic radiography may be 1st diagnostic imaging to determine cause of unerupted tooth

DIFFERENTIAL DIAGNOSIS

Ameloblastic Fibroma

Entirely radiolucent

Histology may show small foci of calcified material indicating AFO

Odontoma

Larger amount of calcified materialIf odontoma is still developing, may look like AFO

AFO calcified material never resembles teeth

Odontoma is usually self limiting, stops growing after teeth development ends

Adenomatoid Odontogenic Tumor

"Snow flake" or fine calcifications

Mostly in anterior maxilla

Mostly pericoronal

Calcifying Cystic Odontogenic Tumor

Can be pericoronal

Varied amounts of calcifications: If sparse, may resemble AFO

Older mean age group

Calcifying Epithelial Odontogenic Tumor

Occurs in older patients with prevalence in middle age

Usually much larger

PATHOLOGY

Microscopic Features

Small islands of odontogenic epithelium in loose primitive connective tissue that resembles dental papilla

Calcified foci of enamel and dentin matrix formation in close relationship to epithelial structures

CLINICAL ISSUES

PresentationMost common signs/symptomsMissing or unerupted toothTooth may be displacedPainless swelling of affected bone

Demographics

Age2nd decade

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While teeth are developing

Gender: No gender predilection

Treatment

Enucleation

Tumor separates easily from bony bed

Recurrence is rareDevelopment of ameloblastic fibrosarcoma after curettage has been reported but is very rare

DIAGNOSTIC CHECKLIST

Consider

AFO is considered to be stage of development of odontoma and not separate entity by some investigators dueto similarity in histopathology