[Ameloblastic carcinoma and malignant amelobastoma: histological reunderstanding]

Twenty-four cases of malignant ameloblastoma were reported, among them were nineteen cases followed up for 5 to 30 years. Histologic characteristics include predominated proliferation of the peripheral cells with papillary protruding to stroma, replacement of the stellate reticular cells in the follicular center by sarcomatous cells, as well as large and deep-stained or alveolar nuclei with moderate atypia, and high mitosis of the tumor cells. Clinico-radiologically, the tumor showed malignant features such as fast growing recently, pain, anesthesia, cauliflower ulcer, limited mouth opening, and large multilocular radiolucent area with ill-defined border. The biological behavior, nomenclature of the ameloblastic carcinoma or malignant ameloblastoma, and differential diagnosis from other tumors were also discussed.