Multiple Hereditary Exostosis

What is multiple hereditary exostosis?

Multiple hereditary exostosis (MHE) is an inherited disorder in which bony bumps (exostoses) grow on the bones. These bumps are noncancerous but can sometimes make it hard to move if they are near the joints. The size, number, and locations of these bumps vary, but they are usually on the bones of the legs, arms, fingers, toes, shoulders, and pelvis.

The bumps usually continue to grow while a child grows but almost always stop when the child is fully grown. Very rarely, MHE can become a cancerous tumor called chondrosarcoma. This usually happens between the ages of 20 and 50, when the person is fully grown and MHE growth has stopped.

What are the symptoms of multiple hereditary exostosis?

People with MHE tend to be shorter than average and may have bowed arms or legs. They may also complain of stiffness, especially near the elbows, forearms, and hips. The bumps can be painful. Bumps near the knees can make it hard to walk or run. 

How is multiple hereditary exostosis diagnosed?

MHE is usually diagnosed when parents notice painless, hard bumps on their child’s arms or legs. The child’s doctor usually orders an x-ray to confirm the diagnosis.

How is multiple hereditary exostosis treated?

Some people with MHE don’t notice decreases in motion or function and don’t require treatment. But if one of the bumps is painful or makes it hard to move, it can be removed with surgery. If a bump is causing bowed arms or legs, removing the bump may be enough to allow the bone to straighten as the child grows. In more severe cases, surgery to straighten or lengthen the bone also may be required.