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Multiple Hereditary Exostoses

What is multiple hereditary exostoses? 

Hereditary multiple exostoses is a condition that is characterized by multiple, benign chondrogenic lesions that are found on the bones’ surface. Fortunately, there is a very low chance (1-5%) that they become malignant. The most commonly affected bones are the femur, tibia, and humerus. 

What are the symptoms of multiple hereditary exostoses?

Symptoms include:

  • Short stature
  • Deformity of the knees and ankles
  • Issues with range of motion
  • Problems with movement
  • Painful snapping of the muscles and tendons
  • Abnormal limb lengths
  • Prominence of superficial locations

If lesions are on the spine, they can cause additional symptoms like sleep apnea, dysphagia, headaches, pain, dizziness, differences in gait, weakness, paresthesias, and other neurological symptoms. 

There is also a very low chance that the lesions could transform into chondrosarcoma. If the lesions do become malignant, there will be additional symptoms, and they will require additional treatment. 

What causes multiple hereditary exostoses?

Inherited in an autosomal dominant pattern, mutated EXT1, EXT2, and EXT3 genes cause multiple hereditary exostosis. EXT2 mutations result in a higher chance of malignant transformation. 

How is multiple hereditary exostoses diagnosed?

This condition is typically diagnosed within the first decade of life. Affected individuals often notice lesions in the most superficial locations, the tibia and scapula, which can then be found using a radiograph. 

At times, the condition is diagnosed at birth if the parents have already been diagnosed, as doctors will specifically look for it. 

What are the treatments for multiple hereditary exostoses?

For many, treatment is not necessary; they remain asymptomatic. If they do need it, surgery is used. Other procedures may be necessary to correct other symptoms, like deformity of the knees and ankles. If the lesions become malignant, other treatment will be needed. 

Where can I find out more about multiple hereditary exostoses?

Multiple Hereditary Exostoses Articles