Ameloblastic carcinoma developing in preexisting ameloblastoma with a mutation of the p53 gene: a case report.

Abstract

Ameloblastic carcinoma is a rare malignant odontogenic tumor. Here we present a case of a large ameloblastic carcinoma, which developed in a preexisting ameloblastoma in the right submandibular region. The patient was an 84-year-old woman who had received several surgical procedures for ameloblastoma, including a segmental mandibulectomy. The dimensions of the tumor were 12 × 8 × 5 cm, and both benign ameloblastoma and ameloblastic carcinoma were observed histologically. Based on histologic diagnosis, immunohistochemical staining and sequence analysis for p53 were performed. Overexpression of p53 was observed only in the ameloblastic carcinoma. Additionally, a mutation of the p53 gene (TP53) in exon 5 was found by sequence analysis in the ameloblastic carcinoma. This is the first case of ameloblastic carcinoma with a mutation of the p53 gene that has been associated with carcinomatous transformation.