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Introduction • Adamantinoma, adamantoblastoma, multilocular cyst • True neoplasm of enamel organ type tissue which does not undergo differentiation to the point of enamel formation 2nd most common odontogenic neoplasm worldwide, • most common (61.5%) odontoplasmic neoplasm in India www.facebook.com/notesdental.

Pathogenesis • Its said to be of varied origin, conceivably may be derived from — Cell rests of the enamel organ, either remnants of • Dental lamina • Hertwig's sheath • Epithelial rests of Malassez. — Epithelium of odontogenic cysts, particularly the dentigerous cyst and odontomas. — Disturbances of the developing enamel organ. — Basal cells of the surface epithelium of the jaws. — Heterotopic epithelium in other parts of the body, especially the pituitary gland. Overexpression of TNF-a, antiapoptotic proteins (Bcl-2, BCI- • XL), and interface proteins (fibroblast growth factor [FGF], matrix metalloproteinases [MMPs] www.facebook.com/notesdental.

Variants of Ameloblastoma — Central (intraosseous) ameloblastoma — most common, 2nd common odontogenic tumor — Peripheral (extraosseous) ameloblastoma — soft tissue — Pituitary ameloblastoma (cranio pharyngioma, Rathke's pouch tumor) — Adamantinoma of long bones www.facebook.com/notesdental.

Clinical Features: Central Type • 10 years through 90 years. • No significant sex predilection • Occurs in all areas of the jaws - mandible is the most commonly affected area (more than 80%) — Molar angle ramus area — 3 times more commonly than the premolar and anterior regions combined • It may be either solid or unicystic type • Usually asymptomatic and are discovered either during Routine radiographic examination Or because of asymptomatic jaw expansion www.facebook.com/notesdental.

www.facebook.com/notesdental.

Clinical Features: Peripheral (extraosseous) Ameloblastoma • Histologically resembles the typical central ameloblastoma But occurs in the soft tissue outside and overlying the alveolar bone. • Originate from either surface epithelium or remnants of dental lamina Slight predilection for males, 2 : 1 ratio of mandible over the maxilla Found as nodules on the gingiva, varied in size from 3 mm- 2 cm in diameter Relatively innocuous, lacks the persistent invasiveness of the intraosseous lesion Very limited tendency for recurrence • www.facebook.com/notesdental.

Peripheral (extraosseous) Ameloblastoma www.facebook.com/notesdental.

Pituitary ameloblastoma • Neoplasm involving the central nervous System. • grows as a pseudoencapsulated mass • Usually found in suprasellar area but sometimes it may be found in the intrasellar area. • It may also destroys the pituitary gland • Peak Incidence - 13 and 23 years of age • Patient may have endocrine disturbance, drowsiness or even toxic symptoms. www.facebook.com/notesdental.

Pituitary ameloblastoma na I.ST 10497 13/26 L2.O SOL www.facebook.com/notesdental 12-97.

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Radiographic Features It may be either multilocular or unilocular • Multilocular cyst like lesion of the jaw — tumor exhibits a compartmented appearance — With septa of bone extending into the radiolucent tumor mass — Honey Comb or soap bubble www.facebook.

Slow growth of the Ameloblastoma Radiograph taken at intervals of two years www.facebook.com/notesdental.

Histological Features • Six histopathologic subtypes — Follicular - 29.5% recurrence rate — Acanthomatous - 4.5 % recurrence rate — Granular cell — Basal cell — Desmoplastic — Plexiform - 16.7% recurrence rate • Mixtures of the different patterns commonly are observed. • Very few lesions are found to be composed purely of one subtype • Lesions are subclassified according to the predominant pattern that is present. www.facebook.com/notesdental.

Histological Features • Stroma: moderately to densely collagenized CT. • Epithelial tissue — Disconnected islands, strands, and cords within the collagenized fibrous CT stroma - vary considerably in size — Consist of tall columnar cells with hyperchromatic nuclei, reverse polarity of the nuclei, and subnuclear vacuole - characteristic palisading pattern — This formation mimic normal embryologic development of the tooth bud at the stage of enamel matrix production www.facebook.com/notesdental.

Histological Features • Zone of hyalinization of the collagen - present immediately adjacent to the epithelium — Fibroblasts are almost totally absent within the zone — Attempt to complete its embryologic function and produce enamel matrix, signals the connective tissue to induce dentin formation — But cells in the CT are unable to differentiate into odontoblasts and ends up with hyalinization www.facebook.com/notesdental.

Follicular (Simple) Ameloblastoma • Most commonly encountered variant • Many small discrete islands of tumor • Composed of a peripheral layer of cuboidal or columnar cells • This strongly resemble ameloblasts or preameloblasts • It enclose a central mass of polyhedral, loosely arranged cells resembling the stellate reticulum www.facebook.com/notesdental.

Follicular (Simple) Ameloblastoma Low Power High Power www.facebook.com/notes.

Follicular (Simple) Ameloblastoma • Clinically, ameloblastoma has been found to be of 2 types i.e solid and cystic • CYSTIC — Stellate reticulum like tissue has undergone complete breakdown or cystic degeneration, www.facebook.c.

Plexiform Ameloblastoma • Ameloblast like tumor cells are arranged in irregular masses • Network of interconnecting strands of cells • Strands is bounded by a layer of columnar cells • Between these layers may be found stellate reticulum like cells - less prominent comparatively. • double rows of columnar cells are lined up back to back. www.facebook.com/notesdental.

Plexiform Ameloblastoma www.facebook.com/notesdental.

Plexiform Ameloblastoma www.facebook.com/notesdental.

Acanthomatous Ameloblastoma • Cells occupying the position of the stellate reticulum undergo squamous metaplasia, • Sometimes with keratin formation in the central portion of the tumor islands. • This usually occurs in the follicular type of ameloblastoma. • On occasion, epithelial or keratin pearls may even be observed. www.facebook.com/notesdental.

Acanthomatous Ameloblastoma www.facebook.com/notesdental.

Granular Cell Ameloblastoma • Marked transformation of the cytoplasm, usually of the stellate reticulum like cells -very coarse, granular, eosinophilic appearance. • This often extends to include the peripheral columnar or cuboidal cells as well. • Ultrastructural studies, cytoplasmic granules represent lysosomal aggregates • This type appears to be an aggressive lesion with a marked recurrence • In addition, several cases of this type have been reported as metastasizing. www.facebook.com/notesdental.

Granular Cell Ameloblastoma www.facebook.com/notesde.

Basal cell type of Ameloblastoma • Considerable resemblance to the basal cell carcinoma of the skin. • Rarest histologic subtype • Epithelial tumor cells are more primitive and less columnar • Generally arranged in sheets, more so than in the other tumor types www.facebook.com/notesdental.

Basal cell type of Ameloblastoma Islands of hyperchromatic basaloid cells with peripheral palisading www.facebook.com/notesdental.

Desmoplastic Ameloblastoma • Characteristically found in a dense collagen stroma that may appear hyalinized and hypocellular. • Greater tendency to grow in thin strands and cords of epithelium rather than in an island like pattern. • Epithelial proliferation almost seems to be flattened or cuboidal rather than columnar and fragmented by the dense hyalinized stroma. • Reverse polarity of nuclei and subnuclear vacuole formation may be difficult to recognize • Increased production of the cytokine known as transforming growth factor-b (TGF-ß) www.facebook.com/notesdental.

Desmoplastic Ameloblastoma Thin cords of ameloblastic epithelium within a dense fibrous connective tissue stroma. www.facebook.com/not.

UNICYSTICAMELOBLASTOMA • Second and far less frequent - 6% • Comparatively found in younger population • Associated with an impacted tooth • Often provisional diagnosis is dentigerous cyst • Considerably better overall prognosis and a much reduced incidence of recurrence. www.facebook.com/notesdental.

UNICYSTICAMELOBLASTOMA A. single large cystic space with prominent basal cells in lining and no inflammation. B, eosinophilic luminal cells overlie stellate reticulum—like areas, and basal cells exhibit palisaded nuclei. www.facebook.com/notesdental.

Differential Diagnosis • Small and unilocular ameloblastoma — Residual cyst— history of extraction of the teeth. — Lateral periodontal cyst —found in incisor, canine and premolar area in maxilla and ameloblastoma occur in mandibular molar area — Giant cell granuloma — Traumatic bone cyst — Primordial cyst • Multilocular ameloblastoma — Odontogenic myxoma www.facebook.com/notesdental.

Treatment Objective: complete removal of the neoplasm based on — individual patient situation — best judgment of the surgeon — lesion involving, mandible or maxilla • Include both radical and conservative surgical excision, curettage, chemical and electrocautery, radiation. • Or a combination of surgery and radiation. • Curettage is least desirable - highest incidence of recurrence • Radiation - highly radioresistant, so not preferred now www.facebook.com/notesdental.

Case : Ameloblastoma.

Case : Ameloblastoma.

Case : Ameloblastoma.

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