咬筋に生じた粘液線維肉腫の1例

A case of myxofibrosarcoma presenting in the masseter muscle

はじめに

　粘液線維肉腫（myxofibrosarcoma：MFS）は高齢者の四肢に好発し，無痛性で緩徐に増殖する，頭頸部では稀な悪性軟部腫瘍である。今回われわれは，咬筋原発と考えられるMFSの1例を経験したので報告する。

　Myxofibrosarcoma is a malignant soft tissue tumor that is common in the extremities of elderly people, but rarely occurs in the head and neck region.

　A 63-year-old man presented with a 45 mm mass in his right cheek region. Preoperative contrast-enhanced MRI and echography revealed no clear malignant findings. Tumor excision was performed；however, the postoperative pathological diagnosis was high-grade myxofibrosarcoma. The tumor has a high postoperative local recurrence rate, although preoperative diagnosis is difficult.

　The patient had been well without tumor recurrence or metastasis at the latest follow-up, 34 months after the surgery.