So-called 'hybrid' lesion of desmoplastic and conventional ameloblastoma: report of a case and review of the literature.

So-called 'hybrid' lesion of ameloblastoma, which is composed of desmoplastic ameloblastoma and conventional follicular/plexiform ameloblastoma, is an unusual variant of ameloblastoma and only eight cases of 'hybrid' lesion have been published in the English literature. To enhance knowledge of this interesting tumor, we add a case of 'hybrid' lesion that occurred in the right mandible of a 48-year-old Japanese male. Radiographic examination disclosed a honeycomb appearance at the anterior alveolar region, combined with a unicystic radiolucency in the molar region of the mandibular body. Histologically, the former showed microscopic features of desmoplastic ameloblastoma and the latter those of follicular ameloblastoma with focal granular cell transformation. The lesion was enucleated with curettage of surrounding bone and the lesional cavity was marsupialized. Although tumor tissues reappeared at 3, 5, 7 and 14 months after the surgery, the patient has remained disease free for 11 years after the last vaporization by CO2 laser of the recurred tumor. Many more cases of 'hybrid' lesion are needed to clarify the clinicopathological, histopathological and biological characteristics of this interesting variant of ameloblastoma.