頭蓋冠傍骨性骨肉腫の1例

A Case of Parosteal Osteosarcoma at the Cranial Vault

I．はじめに

　骨膜由来の骨肉腫の一型と考えられている傍骨性骨肉腫（parosteal osteosarcoma）は，一見良性腫瘍を思わせる分化した組織像を呈し，全摘により良好な予後が期待できる，通常骨肉腫と生物学的特徴を異にする特異な骨肉腫である^5,6）．その発生部位は，大腿骨，脛骨，上腕骨，腓骨などの長管骨の骨幹端で，上顎骨，下顎骨などの顔面骨発生例の報告も散見されるが，頭蓋冠発生例の報告は，極めて稀である．本邦例としては，Iemotoらの側頭骨に発生した25歳女性例が報告されているにすぎない^4）．

　われわれが経験した頭蓋冠傍骨性骨肉腫に関し，若干の文献的考察を加え，報告する．

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 ex-isted between the temporal muscle and the periosteum. The histologic-al diagnosis was parosteal osteosarcoma. There have been only 12 cases of parosteal osteosar-coma of the skull reported. The pathological, neuror-adiological findings and treatment of parosteal osteosar-coma 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 encoun-tered.

A small tumoral attachment existed at the parietal re-gion. The tumor was detached from the skull and the surrounding cranial bone was removed.