Aggressive (malignant?) epithelial odontogenic ghost cell tumor

Although the calcifying odontogenic cyst (COC) is a well-established pathologic entity, it has been recognized that there is an odontogenic neoplasm with histologic features similar to the COC that has often been diagnosed as COC. Investigators have applied several terms to this neoplasm, but we prefer the term epithelial odontogenic ghost cell tumor (EOGCT). No reports have appeared previously in the literature describing either carcinoma arising in a COC or malignant EOGCT. Three cases are reported here with aggressive growth and histologic features strongly implying a malignant potential, although none is known to have metastasized. Two occurred in the maxilla and one in the mandible. One was discovered 9 years following removal of a typical COC, and another recurred rapidly after excision.