惡性周邊神經髓鞘腫瘤通常來源於臀部和下肢坐骨神經周圍附近的神經細胞。往往與疼痛和感覺遲鈍有關，而當壓迫到相關的神經時會發展成頑固性肢體疼痛。在這份病例報告中，我們提出了一個不常見的左臀部惡性周邊神經鞘腫瘤的個案，且一開始伴隨有進行性感覺遲鈍和麻木等症狀在左大腿後側。雖然病患接受了左側下肢肢體保留手術與輔助性放射治療和化學治療，但這些腫瘤仍然無情地快速成長。然後，惡性周邊神經髓鞘腫瘤壓迫到病人左側坐骨神經並造成頑固性肢體疼痛。最後病人因為惡病體質而往生。

　　Malignant peripheral nerve sheath tumor usually originates from peripheral nerve cells of sciatic nerves in the buttock and lower extremities. It often is associated with pain and dysesthesia, and develops intractable limb pain when compressing the associated nerve. In this report, we present an unusual left buttock malignant peripheral nerve sheath tumor case with progressive hypoesthesia and numbness over the posterior aspect of left thigh in the beginning. Though he had undergone limb-sparing resection with adjuvant radiation therapy and chemotherapy, this tumor progressed quickly and relentlessly. Finally, the malignant peripheral nerve sheath tumor compressed the left sciatic nerve and developed intractable limb pain, and the patient passed away with cachexia.