Malignant transformation of a giant cell tumor 25 years after initial treatment

The current authors report a patient in whom a malignant fibrous histiocyto ma developed long after a benign giant cell tumor of bone was removed from the same site. Twenty-five years after a benign giant cell tumor of the lat eral condyle of the proximal tibia had been treated by curettage and iliac bone grafting without radiotherapy, a 53-year-old woman noted progressive p ain and an enlarging mass in the same area, Radiographs showed osteolytic c hange, whereas magnetic resonance imaging indicated a tumor arising at the site of the giant cell tumor and extending beyond the bone. Examination of an open biopsy specimen showed a high-grade malignant fibrous histiocytoma with some areas rich in giant cells, After five courses of caffeine assiste d intraarterial chemotherapy, the tumor was resected with an adequate margi n, and the defect was reconstructed with an implanted prosthesis of corresp onding shape. The extensor mechanism of the knee was reinforced using an al lograft of fascia from the tensor fascia lata muscle. The resected specimen showed a good histologic response (95% tumor necrosis) to preoperative che motherapy, Excellent function in the knee has been regained with no evidenc e of disease recurrence. Caffeine potentiated chemotherapy was effective in minimizing the extent of tumor excision, in this case of high-grade malign ant fibrous histiocytoma representing transformation from a benign giant ce ll tumor.