Recurrent tumours of ameloblastoma: Clinicopathologic features and diagnostic outcome

Abstract

Background: Ameloblastoma is a benign epithelial odontogenic tumor with a tendency for recurrence. The recurrent tumors behave unpredictably with atypical microscopic changes and likelihood of malignant transformation. Aims: To study the clinicopathologic features and diagnostic outcome of recurrent tumors of ameloblastoma in Enugu. This is a six-year (2012-2017) retrospective study of 17 consecutive patients with recurrent tumors of ameloblastoma in a Teaching Hospital in Nigeria. Materials and Methods: The relevant clinicopathologic information, histology slides, and blocks were retrieved and reviewed. Descriptive analysis was used to determine the frequency, tables for categorical variables, and a Chi-square test was used to determine the statistical significance. Result: Recurrent tumors constituted 33.3% (17/51) of all confirmed diagnoses of ameloblastoma. The diagnostic outcome of the recurrent tumors was conventional ameloblastoma 58.8% (10), unicystic ameloblastoma 5.9% (1), and ameloblastic carcinoma 35.3% (6). There was bilateral mandibular extension in 60.0% (9), pain 58.8% (10), ulceration 29.4% (5), and matted lymph nodes 5.9% (1). Tumors with positive fluid aspirates 82.4% (14) yielded dark-brown fluids in 90.0% (9) of recurrent ameloblastomas and in 66.7% (2) of ameloblastic carcinomas. Atypical peripheral hyperplasia, nuclear hyperchromatism, and increased vascularization were commonly observed in benign recurrences. The frequency of recurrence is significantly associated with the biological behavior of ameloblastoma P = 0.03. Conclusion: Recurrent tumors of ameloblastoma presented atypical features and malignant transformation.