A 54-year-old black man presented with a soft-tissue sarcoma of the left anterior thigh. Surgical staging studies and initial biopsy results identified the lesion as a grade IIB pleomorphic liposarcoma. After radical hip disarticulation, follow up pathologic studies of the disarticulated limb showed the tumor to be confined to the anterior compartment of the left thigh without extracompartmental extension. The post-excisional surgical pathology report identified at least four different malignant mesenchymal elements: liposarcoma, myosarcoma, chondrosarcoma, and extraosseous osteogenic sarcoma. The sarcoma was therefore reclassified as a malignant mesenchymoma. The fact that the tumor was found to be intracompartmental at the time of surgery changed the staging of the tumor to stage IIA. A radical surgical margin, as recommended by Enneking, remained the treatment of choice. Three months postoperatively, the patient had chest pain and dyspnea. Chest films revealed multiple pulmonary nodules and the patient died of pneumonia 3 months later.