Collision lesion of mandible--coexistence of keratocystic odontogenic tumor with central giant cell granuloma: a rare case report.

AIM AND BACKGROUND An odontogenic keratocyst (OKC) or keratocystic odontogenic tumor (KCOT) and giant cell granuloma (GCG) in the jaws are common lesions which have been studied extensively in detail over the years. However, a lesion showing features of both is exceptionally rare and is reported only twice in the literature till date. CASE DESCRIPTION A rare case of OKC in mandible showing foci of GCG like areas is reported in a 29 years old male patient. CONCLUSION It seems to be a collision lesion, though the possibility of KCOT showing a reactive response to form giant cells or it being a rare variant cannot be totally ruled out. CLINICAL SIGNIFICANCE This entity requires aggressive treatment since biological behavior of this unique lesion is difficult to predict unless more of such lesions are reported and followed up in future.