Mucinous fibrous sarcoma, also known as mucinous malignant fibrous histiocytoma, is a malignant soft tissue tumor that is more common in elderly patients, slightly more common in males. it is more common in patients aged 60 to 80 years old and rarely occurs in patients younger than 20 years old. Qu Huayi, Department of Bone Oncology, Peking University People’s Hospital The most common site of the tumor is the extremities, including the periphery of the limb girdle bone, and the lower extremity is common. Notably, about half of the patients occur in the subcutaneous, superficial layer of the deep fascia, and the other lesions occur in the deep subfascial and muscular layers. Mucinous fibrosarcoma has a more specific tumor tail sign phenomenon on MRI that can aid in the diagnosis, and the presence of this sign also suggests a more extensive tumor resection to reduce postoperative local recurrence. Local recurrence is common after tumor resection, so the scope of surgery should be wide enough to reduce tumor recurrence. Metastases are rare in low-grade malignant mucinous fibrosarcoma, but about 20-30% of patients with moderate and highly malignant mucinous fibrosarcoma may develop lung metastases, bone metastases, and even lymph node metastases in some patients. Treatment is based on extensive surgical resection.