Abstract Malignant fibrous histiocytoma—currently known as undifferentiated pleomorphic sarcoma—is the most common soft tissue sarcoma of mesenchymal origin. Undifferentiated pleomorphic sarcoma is commonly located in the extremities, trunk, head, and neck in decreasing order of frequency. We report a case of primary undifferentiated pleomorphic sarcoma of the biceps femoris muscle in a 50-year-old man complicated by hemorrhage. Diagnostic workup included imaging, histopathology, and positive results on immunohistochemistry, especially CD68. High-grade liposarcoma and rhabdomyosarcoma were regarded as differential diagnosis of undifferentiated pleomorphic sarcoma. Demonstration of spontaneous hemorrhage within the lesion on follow-up ultrasonography done at one month from the time of diagnosis deserves special mention in this report. Radical excision with tumor-free margins of the biceps femoris and tendon reconstruction were undertaken. MRI at six-month follow-up did not reveal tumor recurrence at the site of surgery and CT chest did not reveal metastases.
Reddy Ravikanth (2025) studied this question.