Extraskeletal myxoid chondrosarcoma. A clinicopathologic study of ten patients with long-term follow-up.

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma that has been reported to have a relatively good prognosis. The authors report ten patients with EMC on whom there was a minimum follow-up of 10 years. The patients' ages ranged from 31 to 72 years (mean, 57 years); there were six men and four women (seven white, three black). The tumor locations included the knee area and thigh (three patients each), the shoulder (two patients), and the leg and foot (one patient each). The tumors ranged from 3.5 to 18 cm in greatest dimension (median, 11.5 cm). All cases had typical histologic features. Lung metastases developed in all patients but one, and three patients had extrathoracic metastases (one in regional lymph nodes; one in subcutis; and one widespread). Four of the patients who had metastases also had local recurrence, as did the only patient without known metastases. Seven patients died of tumor at 4, 5, 8, 10, 15, 16, and 17 years, respectively, and the three remaining patients were alive with metastatic disease at latest follow-up of 13, 14, and 16 years. The authors' results are distinctly different from those previously reported in series with shorter follow-up times. The authors conclude that extraskeletal myxoid chondrosarcomas are indolent but resilient and capricious tumors with a high potential for metastasis, especially to the lungs, over the long-term.