Three times more common in males than females. Also known as an exostosis. Benign lesion composed of a stalk and a rounded bony lesion, capped by cartilage. Most freqently seen near the ends of long bones. Irregularly mushroom shaped lesions, from 1-20 centimeters in size.
External surface is made of cartilage.
Inner portion composed of bone, often with a marrow cavity. Both the bone and the cartilage are histologically benign. Can occur as a solitary lesion or as one of multiple lesions. Individuals with multiple hereditary exostosis, an autosomal dominant hereditary disease, can have several hundred of these lesions. Present as slow growing masses which can be painful.