Odontogenic ghost cell carcinoma: report of four new cases and review of the literature.

Only 12 odontogenic ghost cell carcinomas (OGCC) have been reported in the English language literature to date. This article reports four additional cases of this rare odontogenic tumour and examines them in relation to those previously described. Judging from the number of published cases, the OGCC is more prevalent in Asians than other racial groups, occurs more often in the maxilla than the mandible, and is slightly more common in males than females. Histologically, elements of a benign calcifying odontogenic cyst (COC) can be identified in all the malignant variants, either separated or admixed with the malignant epithelial component. The latter can consist of either small basaloid cells or large epithelial cells. Despite the differing histological presentations, the biological behavior of the tumour is unpredictable, with some cases characterized by relatively indolent growth and others by a locally aggressive and potentially fatal course. The tumour apparently arises most often from malignant transformation of a preexisting benign COC, although it may also develop from other odontogenic tumours.