Ollier's disease with multiple sarcomatous transformations.

A 53-year-old man had the monomelic form of Ollier's disease, which resulted in deformity of the left leg. The patient was otherwise well until pain and increasing size of the left thigh led him to seek treatment. Biopsy revealed chondrosarcomatous transformation in the distal left femur. Hip disarticulation was performed. This case is unusual in that multiple foci of chondrosarcomatous transformation at various stages of development were present throughout the left femur, tibia, and fibula.