[Orbital invasion of a maxillary ameloblastoma].

A 66-year-old man with a history of repeated surgery, external radiation and brachytherapy for ameloblastoma presented with a recurrence of the tumor with sinus, intraorbital and skull base infiltration. Histopathologic examination of the resected orbital and sinus tissue confirmed the diagnosis of ameloblastoma. Immunohistochemical staining for CD56 was strongly positive in the tumor cells. Although ameloblastoma is usually a low-grade malignant tumor, it can be locally aggressive with invasion of the surrounding tissue. Maxillary ameloblastomas are more likely to infiltrate the orbit.