Ghost cell odontogenic carcinoma arising from calcifying cystic odontogenic tumor: a case report.

Ghost cell odontogenic carcinoma (GCOC) is an exceptionally rare and malignant odontogenic tumor with aggressive growth characteristics. We describe a case of GCOC which was considerably derived from a previously resected calcifying cystic odontogenic tumor (CCOT). Cellular atypia, mitotic activity, Ki-67 labeling index and matrix metalloprotease-9 positive expression rate were all increased in the currently resected specimen compared to the initial one. This is a rare case of malignant transformation of CCOT to GCOC with respect to its histopathological and immunohistochemical findings.