Intraosseous squamous cell carcinoma arising in association with a squamous odontogenic tumour of the mandible

We report a rare occurrence of intraosseous squamous cell carcinoma (SCC) arising in association with a squamous odontogenic tumour (SOT), which had not previously been documented in the literature. A 53-year-old man had, for 5 years, a well-demarcated radiolucency attached to the impacted third molar of the mandible. The enucleated specimen had a characteristic pattern of SOT, but in which a few epithelial islands showed atypical features suggestive of SCC. Intense p53-, proliferating cell nuclear antigen- and Ki-67-positive cells were detected in carcinoma areas. Within 2 months, aggressive bone destruction showing typical findings of intraosseous SCC appeared. The present tumour is presumably a malignant variant of SOT. (C) 1999 Elsevier Science Ltd. All rights reserved.