[A case of parosteal osteosarcoma at the cranial vault].

A rare case of parosteal osteosarcoma of the cranial vault has been reported. A 32-year-old male was admitted complaining of a hard scalp mass at the left temporoparietal region for several years. On admission he showed no neurological abnormalities. The craniogram, CT and MRI revealed a calcifying mass attached by a small stalk to the skull, and a radiolucent cleft between the tumor and the skull. On operation, the tumor proved to be hard, and it existed between the temporal muscle and the periosteum. A small tumoral attachment existed at the parietal region. The tumor was detached from the skull and the surrounding cranial bone was removed. The histological diagnosis was parosteal osteosarcoma. There have been only 12 cases of parosteal osteosarcoma of the skull reported. The pathological, neuroradiological findings and treatment of parosteal osteosarcoma were the main topics of discussion. This disease should be considered as one of the possible etiologies when a patient with a tumor of the skull is encountered.