Hereditary multiple osteochondromas



What is hereditary multiple osteochondromas?

Hereditary multiple osteochondromas (HMO) (formerly called hereditary multiple exostoses) is a genetic condition in which people develop multiple benign (noncancerous) bone tumors that are covered by cartilage (called osteochondromas).

These tumors most commonly develop on the metaphysis of the long bones of the lower and upper extremities. Sometimes even the digits are involved in some cases of hereditary multiple osteochondromas.

The number and location of osteochondromas varies greatly among affected individuals. These tumors are not present at birth, but almost all affected people develop multiple osteochondromas by the time they are 12 years old. Once the bones stop growing, the development of new osteochondromas also usually stops.

These lesions may lead to certain musculoskeletal deformities, along with short stature, compression of the nerves and even the range of motion of the affected extremity is decreased.

How common is hereditary multiple osteochondromas?

Hereditary multiple osteochondromas is an extremely rare genetic pathological condition. Please discuss with your doctor for further information.


What are the symptoms of hereditary multiple osteochondromas?

The common symptoms of hereditary multiple osteochondromas are:

  • Abnormality of the humerus
  • Abnormality of tibia morphology
  • Failure to thrive
  • Multiple exostoses
  • Abnormality of femur morphology
  • Abnormality of the dentition
  • Abnormality of the metaphysis
  • Anteverted nares
  • Aseptic necrosis
  • Bone pain
  • Cranial nerve paralysis
  • Genu valgum
  • Hypoplasia of the ulna
  • Madelung deformity
  • Micromelia
  • Muscle weakness
  • Radial bowing
  • Short stature
  • Abnormal pericardium morphology
  • Abnormal pyramidal signs
  • Chondrosarcoma
  • Dilatation
  • Elbow dislocation
  • Hemiplegia/hemiparesis
  • Osteoarthritis
  • Osteolysis
  • Pelvic bone exostoses
  • Recurrent fractures
  • Scoliosis
  • Synostosis of joints

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

If you have any signs or symptoms listed above or have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.


What causes hereditary multiple osteochondromas?

As stated, mutation in genes EXT1 or EXT2 is responsible for the development of hereditary multiple osteochondromas. The function of these genes is to suppress tumors. This condition is inherited as an autosomal dominant trait in which only one copy of the defective gene from either parent is good enough for a child to get this condition.

In some cases, there may be de novo mutations or spontaneous mutations in which a child can get this condition with any prior family history of hereditary multiple osteochondromas. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary to cause a particular disease. The abnormal gene can be inherited from either parent or can be the result of a new mutation in the affected individual. Studies suggest that individuals with EXT1 mutations tend to have more symptoms than those with EXT2 mutations of hereditary multiple osteochondromas.

Risk factors

What increases my risk for hereditary multiple osteochondromas?

Please consult with your doctor for further information.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is hereditary multiple osteochondromas diagnosed?

If the child has a family history of hereditary multiple osteochondromas then the diagnosis of this condition becomes easier. A thorough clinical evaluation along with radiographic studies in the form x-ray, MRI or CT scans of the affected area may point towards a diagnosis of it.

Additionally, a molecular testing will clearly show mutations in EXT1 or EXT2 gene which will confirm the diagnosis of it.

How is hereditary multiple osteochondromas treated?

The front line treatment for hereditary multiple osteochondromas is surgery. This is quite essential for relief of symptoms like pain and decreased range of motion. It also helps in restoring normal circulation through the affected area which tends to get impaired as a result of hereditary multiple osteochondromas. In case if these osteochondromas become malignant then surgical removal followed by chemotherapy and radiation therapy is required for treatment.

The signs that an individual is having a malignant tumor are pain and an accelerated growth of the tumor. It is essential for children with this condition to have regular screenings done to look for signs of any malignancy and if present prompt treatment should be given so as to remove the malignant lesions that develop as a result of hereditary multiple osteochondromas.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage Hereditary multiple osteochondromas?

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.


Review Date: February 23, 2018 | Last Modified: January 30, 2018

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