Primary intraosseous odontogenic carcinoma arising in an odontogenic cyst or de novo: a clinicopathologic study of six new cases.

The term primary intraosseous odontogenic carcinoma (PIOC) has been primarily used to describe a squamous cell carcinoma within the jaws arising either from a previous odontogenic cyst or de novo. Here, we report 6 new cases of PIOC, affecting 4 female and 2 male patients with a mean age of 56.2 years. Two cases involved the maxilla and 4 cases occurred in the mandible. The typical radiographic presentation was that of a radiolucent lesion with well or ill defined margins. Histopathologically, 4 cases were diagnosed as well differentiated keratinizing PIOC arising from previous odontogenic cysts (2 odontogenic keratocysts and 2 periapical cysts). The remaining 2 cases were poorly differentiated nonkeratinizing PIOC, which appeared to arise de novo. Treatment consisted of surgical removal, with postoperative radiotherapy in 5 cases, and to date neither recurrence nor metastasis have occurred. Knowledge of the clinical, radiographic, and histopathologic features of PIOC allows accurate diagnosis and appropriate treatment of this rare malignancy.