PERIPHERAL AMELOBLASTOMA OF THE VENTRAL TONGUE MIMICKING A PREMALIGNANT LESION: A RARE CASE REPORT WITH IMMUNOHISTOCHEMICAL CONFIRMATION

Abstract

Background: Peripheral ameloblastoma is a rare benign extraosseous odontogenic epithelial tumor accounting for approximately 1–5% of all ameloblastomas. It predominantly arises from the gingival or alveolar mucosa, while occurrence on the tongue is exceptionally rare. Because chronic tongue ulcers frequently suggest premalignant or malignant lesions, diagnosis can be challenging. Case Presentation: A 47-year-old man with type 2 diabetes mellitus, hypertension, and previous cerebrovascular accident presented with a progressively enlarging non-healing ulcer over the left ventral aspect of the tongue for three months associated with contact bleeding. Clinical examination revealed a 5 × 4 cm ulceroproliferative lesion without cervical lymphadenopathy. The lesion was clinically diagnosed as a premalignant lesion of the tongue. Wide local excision was performed. Histopathological examination demonstrated islands of odontogenic epithelium composed of peripheral palisading columnar cells exhibiting reverse nuclear polarity surrounding central stellate reticulum-like cells with focal keratin formation. Surgical margins were free of tumor. Immunohistochemistry demonstrated diffuse CK19 and PanCK positivity, focal calretinin and BCL2 positivity, low basal Ki-67 proliferative activity, and negative EMA expression, confirming the diagnosis of peripheral ameloblastoma. The postoperative course was uneventful, and no recurrence was observed during follow-up. Conclusion: Peripheral ameloblastoma involving the tongue is exceptionally uncommon and may clinically mimic premalignant or malignant lesions. Histopathological examination combined with immunohistochemistry is indispensable for establishing the diagnosis. Complete surgical excision provides an excellent prognosis.