Ameloblastoma and its Management in Oral Surgery

Ameloblastoma

1. AMELOBLASTOMA Presented by , Deepthi p Final bds part ii Dept. Of oral and maxillofacial surgery

2. Introduction A tumour or neoplasm is defined as ‘an abnormal mass of tissue which is uncontrolled and uncoordinated with that of the normal tissue and persists in same excessive manner even after the cessation of the stimulus that evoked the change.’ -Sir Rupert Willis

3. Based on origin 1.Odontogenic 2. Non Odontogenic Based on its nature 1.Benign 2.Malignant Classification

4. 2017 WHO classification of Odontogenic tumours

5. AMELOBLASTOMA- Definition "Usually unicentric, nonfunctional, intermittent in growth, anatomically benign and clinically persistent"- Robinson True neoplasm of enamel organ type tissue. Second most common odontogenic neoplasm. Low grade, basaloid tumour with a variable range of histopathologic patterns, clinical forms and behaviour .

6. History Named as adamantinoma by Louis Charles Malassez because of its histological similarity with adamantinoma of long bones. Coined as ameloblastoma by Churchill and Ivey in 1934. First detailed description given by Falkson in 1879.

7. Classification Clinical classification Conventional/ Multicystic /Solid (most common) Unicystic Peripheral ( extraosseous ) Pituitary ameloblastoma Malignant ameloblastoma Based on histological type Follicular ameloblastoma Plexiform ameloblastoma Acanthomatous ameloblastoma Granular cell ameloblastoma Basal cell type of ameloblastoma Desmoplastic ameloblastoma

8. Etiology Traumatic episodes: Extraction, cystectomy, fractures Infections Dietary deficiency: vitamin D deficiency,Lack of protein intake Virus infection

9. Pathogenesis Ameloblastoma is believed to be derived from a) Cell rest of enamel organ, either remnants of dental lamina or Hertwig's sheath, the epithelial rest of Malassez . b) Epithelium of odontogenic cysts, particularly the Dentigerous cyst & odontomas . c) Disturbance to developing enamel organ. d) Basal cells of the surface epithelium of the jaws. e) Heterotopic epithelium in other parts of body especially the pituitary gland.

10. Clinical features Age: 20-40 years Sex: no significant sex predilection Race: more common in blacks than in white race. Site: mandible > maxilla(more than 80% mandible)with in mandible molar ramus area is affected three times more commonly than premolars & anteriors .

11. Signs and symptoms It starts as a slow growing, painless, hard, non tender, ovoid swelling which often enlarges in size as it causes little discomfort in early stage. Facial asymmetry. Mobilty of teeth and exfoliation. Ill fitting dentures. Pain or paresthesia if impinges on nerve. Inability to occlude. Ulcerations.

12. Radiographic features Presents a unilocular or multilocular radiolucency in diff forms and shapes. 50% multilocular,2% peripheral and 6% unicystic lesions. Multilocular radiolucency with compartmentalised appearance due to bony septa (HONEY COMB or SOAP BUBBLE APPEARANCE). Root resorption and tooth displacement.

13. Small / large unilocular or multilocular lesion may show unerupted toothBuccolingual cortical expansion( hollowing out)

14. Histopathology 6 HISTOLOGIC SUBTYPES : Follicular ameloblastoma Plexiform ameloblastoma Acanthomatous ameloblastoma Granular ameloblastoma Basal cell type of ameloblastoma Desmoplastic ameloblastoma

15. Unicystic ameloblastoma Defined as a single cystic cavity showing ameloblastomatous differentiation. Age: The patients are younger than those with the solid/ multicystic form i.e. around 20 yrs. Sex Predilection: equal. Location: 90% occur in the mandible usually in the posterior region. Typically surrounds the crown of unerupted mandibular third molar and resembles dentigerous cyst.

16. Histopathology ACKERMANN CLASSIFICATION: Luminal type: the tumor is confined to the luminal surface of the cyst by fibrous connective tissue partially or totally. Intraluminal: the tumor nodules projects from the cystic lining. Mural: the tumor infiltrates the fibrous cystic wall. (high recurrence rate)One large expansile .

17. Peripheral ( extraosseous ) ameloblastoma Rare type. Develops in soft tissue of gingiva and mucosa. Non invasive. Clinical features: Younger individuals. Mandible>maxilla -In premolar region. Appears as a nodule on the gingiva/ mucosa. Size 3mm-2cm

18. Pituitary ameloblastoma Craniopharyngioma / Rathke's pouch tumor. Neoplasm involving CNS. Grows as a pseudo encapsulated mass in the suprasellar area and destroys pituitary gland. Clinical features: Endocrine disturbances, drowsiness & even toxic symptoms. Histologically similar to oral ameloblastoma but also contains irregular calcified masses as well as occasional focu of metaplastic bone or cartilage.

19. Differential diagnosis Ameloblastic fibroma Odontogenic myxoma Central giant cell granuloma Dentigerous cyst OKC

20. Investigation RADIOGRAPHS Biopsy CT MRI ultrasound

21. Treatment Treatment options include: a) Radical & conservative surgical excision. b) En bloc resection c) Segmental resection d) Curettage e) Chemical & electrocautery f) Antibiotics g) Radiation resistant

22. Simple excision/ enucleation In case of peripheral ameloblastoma,simple excision of the lesion is performed. Means removal of the tumor by scraping it from the surrounding normal tissue. Curettage given a cure rate of only 10%. 60-90% of recurrence rate. Complications of curettage: Seeding into lungs Malignant transformation Failure of curettage is probably related to the fact that the nest of tumor cells extend beyond clinical & radiographic margins of the lesion. Therefore impossible to eradicate the lesion by scraping procedure.

23. En bloc resection Means removal of tumor with a rim of uninvolved bone but maintaining the continuity of jaw. Frequently used therapeutic measure.

24. Segmental resection Means removal of segment of the maxilla / mandible up to & including hemi section or more. Includes hemimaxillectomy & hemimandibulectomy . Most Commonly used treatment. Least chance of recurrence. It is noted that the lesion most likely to recur after segmental resection are those over 5cm.

25. Chemotherapy May be sensitive to platinum agents. May have role in improvement in non surgical patients. Eg; cyclophosphamide, cisplatin,vinblastine , methotrexate etc. RADIATION THERAPY Ameloblastoma is generally radioresistant . Post operatively in patients with gross/microscopic residual diseaseRecurrent disease. Patients who are poor candidates of surgery

26. Prognosis Simple curettage- 90% recurrence rate. Ameloblastoma of maxilla - moreaggressive poor prognosis.

27. Reference Textbook of oral and maxillofacial surgery third edition – SM BALAJI. Shafer’s Textbook of oral pathology – 8 th edition.