Exostoses (Swimmer’s Ear)

Hereditary Multiple Exostoses

Hereditary multiple exostoses is a rare genetic condition characterized by abnormal bony growths (exostoses) at the ends of long bones in the ribs, vertebrae, arms, legs and hipbones, and flat bones such as the shoulder blade. The number and size of growths, and the bones involved vary from person to person. Exostoses develop during childhood and puberty. New growths cease when bones stop growing and adult height is reached, but existing exostoses continue to grow slowly.

The exostoses may be felt under the skin. Bone growth may be affected, leading to short stature and differences in the length of your right and left limbs. It can cause bowing of the forearm and ankles, and abnormal hip joint development, which leads to pain and difficulty in walking. The bony overgrowths may irritate the surrounding tissue and compress important structures such as nerves and blood vessels. Hereditary multiple exostoses can lead to problems during pregnancy and childbirth. It is usually benign and rarely turns cancerous.

Hereditary multiple exostoses is usually diagnosed before the age of 12 with X-ray imaging and is confirmed with genetic testing. However, if you have a family history of hereditary multiple exostoses, genetic testing may be performed to identify the disorder in your child even before birth.

Hereditary multiple exostoses has no cure. Most often, it does not disable you, and you can live a healthy and active life. Your doctor will treat pain with medication. Sometimes, surgery may be necessary to remove large exostoses and growths that are compressing important surrounding structures or causing tissue irritation. Periodic monitoring of your exostoses is necessary to identify any cancerous changes.