Malignant fibrous histiocytoma arising from a calcifying enchondroma--a case report.

A man, 79 years of age, developed a malignant fibrous histiocytoma which arose in relation to a calcifying enchondroma of the distal femur. Radiographs showed a fracture through an intensely calcified bony tumour with no bony destruction. The clinical diagnosis was a dedifferentiated chondrosarcoma. Histology showed an anaplastic sarcoma with calcified tissue showing extensive areas of necrosis and degeneration. No chondrosarcomatous foci were found.