Subacromial impingement syndrome in hereditary multiple exostoses.

An unusual cause of subacromial pain was observed in a 32-year-old woman with multiple exostoses. The pain was the direct result of the mechanical impingement syndrome from these exostoses. Hereditary multiple exostoses should be investigated systematically, because many other, more common pain-producing conditions are possible. Secondary malignant degeneration of one of the cartilaginous coverings of the exostoses is very rare.