Multicentric chondrosarcomas.

Multicentric chondrosarcomas, other than those from mesenchymal chondroma, are rare and difficult to differentiate from metastatic disease. Eight new patients with multicentric chondrosarcomas are reported. Five patients had chondrosarcomas that were monomelic, 3 had disseminated chondrosarcomas, 3 had synchronous involvement, and 5 had metachronous involvement; 1 patient had Ollier's disease. A bimodal age distribution was apparent: 4 patients were between 62 and 76 years old, and the remaining 4 were between 16 and 33 years old. Average duration of followup was 6 years, 4 months. Each of the patients with synchronous chondrosarcomas had single bone lower extremity involvement and presented with symptoms occurring at only 1 of the 2 sites of tumor. Each of the 5 patients with metachronous chondrosarcomas experienced involvement of a different bone when the second tumor presented. Only 1 of these metachronous chondrosarcomas was limited to the lower extremity. The second tumor occurred in all patients after excellent control of the primary tumor by wide excision. The average duration between diagnosis of the 2 tumors was 4 years, 4 months (range, 8 months-12 years, 9 months). Patients who had nonmonomelic malignancies must be viewed with a considerably more guarded prognosis than those who had monomelic chondrosarcoma because each of the 2 deaths resulting from progressive disease occurred among the 3 patients with nonmonomelic chondrosarcoma. The nonmonomelic malignancies may represent metastatic chondrosarcoma with a rare predilection to bony involvement. Monomelic chondrosarcoma simply may represent lesions analogous to the skip lesions observed in osteosarcoma.