PP115: Ameloblastoma of the jaw bones: A great mimicker offering diagnostic challenge in tertiary cancer centre – An Indian experience

Abstract

Purpose Ameloblastoma is most frequently encountered odontogenic tumor arising from rests of dental lamina, or lining of an odontogenic cyst. Delayed presentation and presence of histologic mimics make the diagnosis challenging. This prompted us to study the clinical, radiological & histopathologic features in ameloblastomas at a tertiary cancer centre and evaluate features of distinction from histologic mimics to attain accurate diagnosis. Material and methods The clinical, radiological details and H& E sections of 70 cases of ameloblastomas were retrieved and reviewed. Histologic typing was done. The treatment modalities and recurrences were studied. Results Mandible was involved in 78.6% cases, maxilla in 21.4%. Swelling was the commonest presenting symptom [98%].The most common radiologic appearance was lytic lesion seen in 75.7.%; 18.6 % were sclerotic masses while 5.7% had a mixed lytic-sclerotic appearance. A well-defined razor-sharp border was the characteristic feature (71.4%). Microscopically, follicular type was the most common [75.7%] Reverse polarity and Stellate reticulum cells; the most crucial diagnostic features; were appreciated in 74.3% & 80% cases respectively. Pseudoepitheliomatous hyperplasia [PEH] occurred in 17.1 % cases, merged with the ameloblastic tumour, making the distinction from Squamous carcinoma difficult in a biopsy. Acanthomatous variant [10%] also mimicked SCC. CK 19 and calretinin positivity helped in differentiating ameloblastoma from PEH & SCC. Follicular and Solid type predominated in cases of recurrences occuring following limited resection [20%]. Conclusions The diagnosis of ameloblastoma is challenging due to heterogeneity in the histology and variety of histologic mimics. Differentiation from benign lesions & tumours is vital in view of its locally aggressive nature which necessitates radical excision, to prevent recurrence. Distinguishing from OSCC in a biopsy is crucial to avoid overtreatment. High index of suspicion, clinico-radiological correlation and IHC are of utmost importance in making the right diagnosis preoperatively, essential for planning adequate treatment.