惡性纖維組織細胞瘤是成年人最常見的惡性軟組織肉瘤，以男性居多，好發於四肢及後腹腔，但是原發於泌尿系統的惡性纖維組織細胞瘤是非常罕見的。本例為62歲男性，在左側輸尿管患有惡性纖維組織細胞瘤，病人接受腎臟輸尿管及膀胱袖口切除。確立診斷主要依據病理顯微及免疫組織化學檢查。病人拒絕接受放射線治療，然而術後追蹤18個月並無復發或轉移的跡象。許多文獻建議針對惡性纖維組織細胞瘤給予輔助性的化學治療或放射線治療，至於效果如何仍需進一步的研究。

Malignant fibrous histiocytomas (MFHs) are the most common soft-tissue sarcoma of adulthood; they have a male preponderance, and often involve the extremities and retroperitoneum, but a primary MFH of the urinary tract is extremely rare. We report a 62-year-old male with MFH of the left ureter, in which a left nephroureterectomy with bladder cuff resection was performed. The diagnosis was established on the basis of the pathologic microscopic findings and immunohistochemistry. Most studies recommend adjuvant chemotherapy or radiotherapy for these tumors, but the role of these treatments needs further investigation.