Isfahan University of Medical SciencesDental Research Journal1735-33279320120821Spindle cell variant of ameloblastic carcinoma arising from an unicystic amelobastoma: Report of a rare case10931093ENVenkateshV. KamathDepartment of Oral and Maxillofacial Pathology, Dr. Syamala Reddy Dental College, Hospital and Research Center, Munnekolala, Marathalli, Bangalore, India. kamathvv2003@yahoo.comKrishnanandSatelurKomaliYerlagudda20120821Malignant transformation of ameloblastomas arising from an odontogenic cyst or de novo is wellrecognized.Malignancies in ameloblastomas may involve metastasis or a local dysplastic change inthe tissue. The latter are classified as ameloblastic carcinomas. A 75-year-old male presented with amandibular cystic swelling, with no evidence of metastasis. Dysplastic ameloblastic cells with spindlecelltransformation were seen arising from a cystic lining with features of a unicystic ameloblastoma.Immunohistochemically the lesion stained positive with cytokeratin 8,19 and alpha smooth muscleactin, but was negative for vimentin. A diagnosis of spindle-cell ameloblastic carcinoma was made.Spindle-cell ameloblastic carcinomas are rare and this is the second case arising from a unicysticameloblastoma reported in literature. The recognition of this transformation and inclusion of thisentity in the classification of ameloblastic carcinomas is stressed.Key Words: Ameloblastic carcinoma, ameloblastoma, odontogenic carcinoma, spindle-celltransformation, unicystic ameloblastoma