Primary intraosseous squamous carcinoma. Report of two cases.

Two cases of primary intraosseous squamous carcinoma (PIOSC) are reported. One PIOSC is in the mandible of a 24-year-old man and appears to be a keratinizing PIOSC arising de novo. The other PIOSC presented in the edentulous maxilla of a 56-year-old man and was diagnosed as a PIOSC arising from an odontogenic cyst. The 2nd tumor subsequently metastasized to a cervical lymph node. Previous reports have noted a favorable prognosis for PIOC arising in odontogenic cysts, and only 3 other instances of metastases of a PIOSC in an odontogenic cyst have been documented.