Benign metastasizing ameloblastoma or malignant ameloblastoma?

Ameloblastoma of the maxilla is a rare odontogenic tumor that rarely metastasizes. We report a patient who was diagnosed with ameloblastoma of the maxilla 6 years ago and had undertaken the operation. However, the recurrence occurred, and further pulmonary disease was discovered. He did not experience chest pain and other respiratory systematic symptoms. Whether this metastasizing ameloblastoma should be ranged among malignant or benign is discussed. The term benign metastasizing ameloblastoma is suggested to describe this kind of tumor.