Malignant ameloblastoma or ameloblastic carcinoma.

The World Health Organization defines malignant ameloblastoma as a lesion exhibiting features of an ameloblastoma in primary and metastatic growths. To cases collected from the literature we have added two of our own cases in which features of an ameloblastoma were coupled with malignant behavior. It was noted that the diagnosis of "malignant ameloblastoma" is at present used in a rather indiscriminate way, resulting in the grouping of lesions that exhibit considerable differences in biological behavior and histomorphology. This might be due to the fact that the WHO classification emphasizes metastasis as a diagnostic criterion but is rather vague in defining histopathologic aspects. It is advocated that the term malignant ameloblastoma be reserved for those lesions that, in spite of a seemingly innocuous histology, have given origin to metastatic growths, while the WHO classification should be modified to include ameloblastic carcinoma as a diagnostic term for lesions that combine features of an ameloblastoma with a less-differentiated histomorphology.