Primary Undifferentiated Pleomorphic Sarcoma of the Biceps Femoris Muscle Complicated by Hemorrhage: An Underrecognized Entity.

Malignant fibrous histiocytoma currently known as undifferentiated pleomorphic sarcoma is the commonest 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 male complicated by hemorrhage. Diagnostic workup included ultrasonography, magnetic resonance imaging (MRI), histopathology and positive results on immunohistochemistry especially CD-68. High-grade liposarcoma and rhabdomyosarcoma were regarded as differential diagnoses 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 a special mention in this report. Radical excision with tumor-free margins of the biceps femoris and tendon reconstruction was undertaken. MRI at six months follow-up did not reveal tumor recurrence at the site of surgery and CT chest did not reveal metastases.