Ameloblastoma

 Definition:

Ameloblastoma is a benign locally aggressive neoplasm arising from the odontogenic epithelium and it is the most common odontogenic neoplasm of the oral cavity.

It was described by Robinson in 1937, as a benign tumor that is:

UNIAC

 “usually unicentric, nonfunctional, intermittent in growth, anatomically benign and clinically persistent.”

Etiology

• Trauma
• Infection
• Previous inflammation
• Extraction of tooth
• Dietary factors
• Viral infection

Histogenesis of Ameloblastoma

Ameloblastomas may arise through:

• Enamel organ of the developing tooth germ.
• Cell rest of Serre (remnants of dental lamina).
• Epithelial lining of the odontogenic cysts,especially the dentigerous cyst.
• The basal cell layer of the oral epithelium(rarely).
• Reduced enamel epithelium.
• Cell rest of Malassez

Clinical Features:

Incidence: Approximately one percent among all

oral tumors and 18 percent of all odontogenic

tumors are ameloblastomas.

Age: Second, third, fourth and fifth decade of life,

the mean age of occurrence is about 32 years. 

Sex: Males are affected more often than females.Tumorsize is usually larger in women

Site: Mandible(80%), especially in them molar-ramus area (70%), although some lesions may develop in the premolar (20%) or symphysis(10%) regions.

Clinical Presentation

• Slow, enlarging, painless, ovoid or fusiform bony hard swelling of the jaw
• Expansion and distortion of cortical plates of jaw and displacement of regional teeth
• Untreated lesions cause extensive destruction leading to "Egg-Shell Cracking" and "Pathological Fracture"

Radiographic Features

• A well-defined, multilocular, radiolucent area in the bone with a typical “honey-comb” or “soap-bubble”appearance
• Few lesions can be unilocular too
• If loculations are large: " Soap-bubble" appearance
• Small loculations: "Honey combed appearance"
• Resorption of roots of adjacent teeth
• May be associated with unerupted tooth
• Margins: Scalloping

Histopathological Features

Various Patterns:

1. Follicular : Most common
2. Plexiform
3. Granular
4. Desmoplastic
5. Basal Cell Pattern

Ameloblastomatous cells shows Vickers and Gorlin Crieteria:

• Peripheral layer of tall columnar cells with Hyperchromasia
• Reverse polarity of nucleus
• Subnuclear vacuole

Follicular Ameloblastoma:

• In follicular type, the neoplastic odontogenic epithelial cells proliferate in the form of multiple, discrete follicles or islands within the fibrous connective tissue stroma
• Each follicle is boarded by single layer of tall columnar cell with reverse polarity
• Central core of loosely arranged cells resembling stellate reticulum
• Cyst formation is common

Plexiform Ameloblastoma

• Neoplastic odontogenic epithelium proliferates in long anastomosing strands or large sheets
• "Fishnet appearance"

Acanthomatous Ameloblastoma

• Extensive squamous metaplasia
• Keratin formation in central portion of follicular ameloblastoma
• May be confused with Squamous Cell Carcinoma

Granular Cell Pattern

• Epithelial cells transform into granular cells
• Cells have eosinophilic granules
• Clinically aggressive

Desmoplastic Pattern

• Islands and chords of odontogenic epithelium with densely collagenized stroma

Basal Cell Pattern

• Least Common Type
• Nests of uniform basaloid cells

TREATMENT

Surgical enucleation of the tumor and thorough

curettage of the surrounding bone.