Late development of a malignant fibrous histiocytoma at the site of a giant cell tumor.

A case of late development of a high grade malignant fibrous histiocytoma at the site of a previously surgically treated giant cell tumor is reported. The patient initially was treated for a benign giant cell tumor of the lateral condyle of the distal femur by curettage, implant of auto and allograft bone, but no radiation. Eighteen years later, he noted progressively increasing pain and disability. Radiographs showed some change, but magnetic resonance imaging clearly disclosed a tumor arising at the site and extending outside the bone. After chemotherapy, the tumor was resected and histologically showed no evidence of a recurrent giant cell tumor, only a high grade malignant fibrous histiocytoma.