Chondrosarcoma, [s8]rare

About 20% of primary bone tumours are chondrosarcomas; they occur in the pelvis (30%), the femur (the lower rather than the upper end, 20%), the ribs (10%), and the skull and facial bones (10%). Most arise de novo, but about 20% arise in patients with chondromatosis, and less than 5% from patients with chondromas. They are less aggressive than osteosarcomas, and spread by local infiltration; blood-stream spread is late. Histological grading is useful in establishing the likely prognosis.

The patient presents with a bony swelling which is often slightly painful and tender. Pelvic masses are hidden by the overlying tissue, and present late.

CHONDROSARCOMA X-RAYS show an area of translucency with trabeculae, multilocular areas of bone destruction, and scattered fluffy areas of calcification. There is usually a surrounding area of soft tissue swelling. Cortical destruction is late, and periosteal reaction is limited. You may see Codman's triangle (32.13) in limb tumours.

THE DIFFERENTIAL DIAGNOSIS includes subacute and chronic osteomyelitis, chondromas, bone cysts, fibrous dysplasia, and other bone tumours. Confirm the diagnosis by biopsy.

PROGNOSIS. Without treatment 5% of patients survive 5 years, and none 15 years. Adequate surgery enables 50% of patients to survive 5 years and 35% 15 years.

MANAGEMENT. Chondrosarcomas are radioresistant; there is no chemotherapy. You can treat most limb tumours surgically. Amputate through the bone or joint proximal to the tumour. The recurrence rate after adequate excision is low. If possible refer the patient.

Early rib lesions have the best prognosis. If you suspect a rib lesion and cannot refer him, resect it with at least 5 cm of rib on either side, and preferably remove some of the neighbouring ribs. He must be intubated and have a general anaesthetic, in case you open his pleura (9.2).