Abstract
An autopsy case of malignant ameloblastoma in a 64-year-old Japanese woman is presented, which started as a benign ameloblastoma with plexiform and follicular patterns, and transformed into a malignant histology with atypical and mitotic tumor cells in the course of several recurrences. An autopsy revealed several relatively large metastases in the lungs bilaterally consisting of malignant ameloblastoma and intracranial invasion of malignant tumor cells to the left temporal lobe. Immunohistochemical staining of proliferating cell nuclear antigen (PCNA) demonstrated a significant increase in the proliferative activity of neoplastic cells between the primary tumor and two recurrent ones (P < 0.01, Newman-Keul's test). This data provides evidence of malignant transformation in a benign ameloblastoma in the course of multiple recurrences. Immunostaining of PCNA may be useful in determining the possibility of malignant transformation in recurrent cases of ameloblastoma.
