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"Ameloblastoma" Odontogenic tumor Oral Pathology
- 1.
- 2. Ameloblastoma "Unicentric, non-functional, intermittent ingrowth, anatomically benign and clinically persistent neoplasm.“ -Robinson
- 3. Synonyms: • Adamantinoma • Adamantoblastoma •Multilocular cyst The ameloblastoma is the most common clinically significant odontogenic tumor. Ameloblastoma are tumors of odontogenic epithelial origin. Slow-growing, locally invasive tumor that run a benign course in most cases. May arise from: 1. Rests of dental lamina, 2. Developing enamel organ, 3. Epithelial lining of an odontogenic cyst 4. Basal cells of the oral mucosa.
- 4. Clinicoradiographic varieties: 1. Conventional solidor multicystic (about 86% of all cases) 2. Unicystic (about 13% of all cases) 3. Peripheral (extraosseous) (about 1% of all cases)
- 5. Conventional Ameloblastoma •Age incidence:3rd & 4th decades •Sex incidence: Slightly more in males •Site predilection: 80% occur in posterior mandible, followed by maxillary molar region. •Signs & symptoms: Slowly growing, painless, hard bony swelling or expansion of jaw. Thinning of cortical plates produces “Egg shell crackling”. •Other symptoms – Tooth mobility ,root resorption and paraesthesia if inferior alveolar nerve is affected.
- 6. RADIOLOGICAL FEATURES • Typically rounded,well defined multilocular radiolucency with scalloped margins. • Large loculations – “SOAP BUBBLE” appearance. • Small loculations- “HONEY COMBED” appearance. • Buccal and lingual cortical expansion is frequently present. • Resorption of the roots of teeth adjacent to the tumor is common.
- 7. HISTOPATHOLOGIC FEATURES • FOLLICULAR •PLEXIFORM • ACANTHOMATOUS • DESMOPLASTIC • GRANULAR CELL • BASAL CELL TYPE • CLEAR CELL TYPE • 7 Subtypes seen:
- 8. FOLLICULAR AMELOBLASTOMA •Most common andrecognizable. •Islands of epithelium resemble dental organ surrounded by mature connective stroma. •Individual follicles show central mass of stellate reticulum like cells surrounded by a single peripheral layer of ameloblast like cells. •Nuclei of peripheral cells are reversely polarized. •Within the islands, cyst formation is common.
- 10. PLEXIFORM AMELOBLASTOMA • Long, anastomosingcords or larger sheets of odontogenic epithelium. • The cords or sheets of epithelium are bounded by columnar or cuboidal ameloblast-like cells surrounding more loosely arranged epithelial cells. • Supporting stroma tends to be loosely arranged and vascular. • Cyst formation is relatively uncommon in this variety.
- 11. ACANTHOMATOUS PATTERN • Central areaof follicles show extensive squamous metaplasia, often associated with keratin formation. • Change does not indicate a more aggressive course for the lesion. • Can be confused with squamous cell carcinoma or squamous odontogenic tumor.
- 12. DESMOPLASTIC PATTERN • Thistype of ameloblastoma contains small islands and cords of odontogenic epithelium in a densely collagenized stroma. • Peripheral columnar ameloblast-like cells are inconspicuous about the epithelial islands.
- 13. GRANULAR AMELOBLASTOMA • Follicles /sheets of cells showing granular cell change. • These cells have abundant cytoplasm filled with eosinophilic granules. • Seen in younger persons and appears to be more aggressive clinically.
- 14. BASAL CELL PATTERN •Least common type. • Lesions are composed of nest of uniform basaloid cells. • No stellate reticulum present centrally and peripheral cells tend to be cuboidal rather than tall columnar.
- 15. DIFFERENTIAL DIAGNOSIS: Odontogenic keratocyst Fibrousdysplasia Ossifying fibroma Central giant cell granuloma TREATMENT • Can vary from simple enucleation to curettage to en-bloc resection. • As lesion spreads through medullary spaces, simple enucleation can leave islands of tumor within the jaws, leading to recurrence. • Marginal resection is the optimal method. • Rarely can undergo malignant transformation.
- 16. UNICYSTIC AMELOBLASTOMA •Controversy, whetherit arises de novo or as neoplastic transformation of odontogenic cyst lining. CLINICAL FEATURES: - •Age incidence: Young individuals. •Sex incidence: More in Males •Site predilection: 90% cases occur in posterior mandible. •Signs & Symptoms: Asymptomatic swelling of jaws. Many lesions contain a tooth inside.
- 17. RADIOLOGICAL FEATURES: - • Typicallyseen as well defined, unilocular radiolucency, many times surrounding the neck of impacted 38 or 48 – impossible to distinguish from dentigerous cyst. • Occasionally, may not be associated with teeth – then they may be diagnosed as OKC or a radicular cyst.
- 18. HISTOPATHOLOGICAL FEATURES: - • Threevariants are recognized(According to Ackermann) 1. LUMINAL UNICYSTIC 2. INTRALUMINAL UNICYSTIC 3. MURAL UNICYSTIC
- 19. Luminal Unicystic Ameloblastoma • Tumoris confined to the luminal surface of the cyst. • The lesion consists of a fibrous cyst wall with a lining that consists totally or partially of ameloblastic epithelium. • Basal layer of columnar or cuboidal cells with hyperchromatic nuclei that show reverse polarity and basilar cytoplasmic vacuolization. • Overlying epithelial cells are loosely cohesive and resemble stellate reticulum.
- 20. Intraluminal Unicystic Ameloblastoma • Oneor more nodules of ameloblastoma project from the cystic lining into the lumen of the cyst. • Lining often shows arrangement similar to plexiform ameloblastoma.
- 21. Mural Unicystic Ameloblastoma • Thefibrous wall of the cyst is infiltrated with typical follicular / plexiform ameloblastoma. • Believed to be more aggressive than other two variants.
- 22. Differential diagnosis- • Enucleation •Local resection Treatment - Odontogenic keratocyst Dentigerous cyst Radicular cyst Ameloblastoma Adenomatoid odontogenic tumor Calcifying epithelial odontogenic tumor
- 23. PERIPHERAL AMELOBLASTOMA • Uncommonand accounts for about 1% to 10% of all ameloblastomas. • Arises from rests of dental lamina. Clinical Features - Painless, nonulcerated sessile or pedunculated gingival or alveolar mucosal lesion. Age – Middle aged persons. Site – posterior gingival and alveolar mucosa. More common in mandible.
- 24. HISTOPATHOLOGIC FEATURES - •Islands of ameloblastic epithelium that occupy the lamina propria underneath the surface epithelium. • Proliferating epithelium may show any of the features described for the intraosseous ameloblastoma. Treatment- • Surgical excision.
Editor's Notes
- #4 The ameloblastoma is the most common clinically significant odontogenic tumor. Ameloblastomas are tumors of odontogenic epithelial origin. Slow-growing, locally invasive tumors that run a benign course in most cases. May arise from, Rests of dental lamina, developing enamel organ, epithelial lining of an odontogenic cyst basal cells of the oral mucosa.