Multiple hereditary exostoses is an autosomal dominant disorder where the main feature is multiple projections of bone in the metaphyses and  on the diaphyses of long bones. In this case report we describe two siblings affected by multiple exostoses.

Our patient is a 26 year-old woman with bony overgrowhs on the knee, wrists and distal ends of the radii. She first noticed enlargement of the tibia in early childhood. She had been evaluated in other hospitals without a definite diagnosis. Physical examination showed bony tuberances on the proximal end of both tibiae, right ssapulae and distal ends of both radii. Radiological examination revealed typical exostoses  at the ends of long bones (radius, humerus andtibia). Her 24-yar old brother had a similar history and physical findings (bony tuberances on distal radii, tibia, femur). Radiological examination revelaed the same abnormalities as his sister, establishing the diagnosis as multiple hereditary exostoses. Although not examined personally, two sisters and the father were claimed to have similar abnormalities.

Multiple exostoses is usually diagnosed during the first decade of life. New outgrowhts and enlargement of old exostoses may occur through adolescence. No new lesions form after puberty.  Thereafter, pain or new growth should be evaluated considering malignant transformation.. Patients should followed for other complications including nerve, spinal chord and blood vessel compression and arthritis. The diagnosis may be delayed as the case under discussion and hereditary exostoses should be included in the differential diagnosos of patients presenting with bony overgrowths.