About exostoses, multiple

What is exostoses, multiple?

Hereditary multiple osteochondromas (HMO) is a rare genetic disorder characterized by multiple benign (noncancerous) bone tumors that are covered by cartilage (osteochondromas), often on the growing end (metaphysis) of the long bones of the legs, arms, and digits. These osteochondromas usually continue to grow until shortly after puberty and may lead to bone deformities, skeletal abnormalities, short stature, nerve compression and reduced range of motion. Hereditary multiple osteochondromas is inherited as an autosomal dominant genetic condition and is associated with abnormalities (mutations) in the EXT1or EXT2 gene.

Hereditary multiple osteochondromas was formerly called hereditary multiple exostoses.

What are the symptoms for exostoses, multiple?

Most people with an exostosis don't have symptoms, but it can cause Pain in certain situations.

Types of Exostosis

Although exostoses can occur on any bone, they're more common in some parts of the body, particularly in or around the foot or in the hip. Bone spurs are often found:

Under the heel. This type of bone spur can be caused by plantar fasciitis. When your plantar ligament (located in the sole of the foot) pulls on your heel, it can cause a buildup of extra tissue. 

Big toe. The base of the big toe is the most common place to develop arthritis in the foot. When a bone spur develops on the top of the big toe, it can keep you from moving it as much as you need to when you walk. This is called hallux rigidus or stiff big toe.

Back of the heel. Also called a "pump bump," Haglund's deformity refers to a bone spur on the back of the heel. This type of exostosis can occur when pump-style shoes rub against the back of the heel. Though it's called a pump bump, any type of shoe with a rigid back can cause this irritation.

Hip. Osteoarthritis wears away the cartilage in the hip and causes the bones to start rubbing together. This friction leads to the growth of bone spurs.  

Other types of exostoses include:

Osteochondroma. This is a growth of bone and cartilage that happens near the bone's growth plates. It usually affects the long bones in the leg, shoulder, or pelvis. Unlike a lot of bone spurs, this type of exostosis happens in younger people, usually between the ages of 10 and 30.

What are the causes for exostoses, multiple?

You can have an exostosis in your:

  • ear canal
  • ankle
  • jaw
  • sinuses
  • long bones of the leg

What are the treatments for exostoses, multiple?

An exostosis may require no treatment at all. But in some cases, treatment may be necessary.

For surfer’s ear: In more serious cases, surfer’s ear can be treated by an operation known as canalplasty. Wearing ear plugs or a head covering may be a way for surfers to avoid this type of exostosis.

For Haglund’s deformity: Haglund’s deformity occasionally requires surgical removal of the bony growth. Conservative, nonsurgical treatments for Haglund’s deformity include:

  • wearing shoes with lower heels
  • wearing open-backed shoes
  • wearing special orthotics in your shoes
  • getting physical therapy, including massage and ultrasound therapy (a method that’s been used for rheumatoid arthritis)
  • taking anti-inflammatory drugs

For paranasal sinus osteoma: Your doctor may recommend surgically removing the osteoma. This depends on whether you can manage your symptoms without surgery.

What are the risk factors for exostoses, multiple?

Here are some of the leading types of exostosis:

Surfer’s ear

“Surfer’s ear” is a bony growth inside the ear canal. The new bone growth occurs along the part of the ear canal leading to the eardrum. It can occur in one or both ears. As the exostosis develops, it can cause hearing loss.

The cause is not certain, but irritation of the bone by water and wind may facilitate the abnormal growth. Surfer’s ear is usually more serious if you’re a surfer or a sailor. Learn how to get water out of your ear if you’re a surfer or swimmer.

The formal name for surfer’s ear is exostosis of the external auditory canal.

Haglund’s deformity (foot)

Haglund’s deformity is a type of exostosis on the heel of the foot. It’s also known as “pump bump,” because it develops when the stiff back of your shoe rubs against the bump in your heel. Other names for this exostosis are Mulholland deformity and retrocalcaneal exostosis.

A common symptom is pain in the heel that doesn’t go away after resting. It occurs most frequently in middle-aged women and can appear on either or both feet.

Contributing factors include having a tight Achilles tendon, having a high arch in your feet, and heredity.

Paranasal sinus osteoma

The paranasal sinuses are four pairs of sinus cavities, which are the air spaces surrounding your nose. In this type of exostosis, there is an abnormal growth of the bone that forms the sinus cavity.

Often you feel no symptoms. But sometimes, even a small growth can cause a lot of pain. The bone growth can block your sinus from draining properly, causing congestion. It may also cause pain by putting pressure on a nearby nerve.

This type of exostosis is often discovered when you get a sinus scan or X-ray.

Buccal exostosis (jaw)

This is a type of abnormal growth on the upper or lower jawbone. It tends to appear in early adolescence. It’s usually painless, but it might affect the way your mouth looks. It also may get in the way when you’re cleaning your teeth.

Buccal exostosis generally shows up near the back of the mouth, but it may be found in other parts of your mouth.

The cause is not yet known. Genetics may play a role, as may heavy use of the jaw.

Osteochondroma (leg, hip, shoulder)

Osteochondroma is the most common type of noncancerous growth on the bones. It usually has no symptoms, but it may cause other complications.

This type of abnormal bone growth most commonly affects the long bones of the leg, the pelvis, or the shoulder blade. It’s also called osteocartilaginous exostosis.

Osteochondroma affects 1 to 2 percent of the population. It occurs during the growth period of the bone. It’s typically noticed in childhood or the teen years.

Symptoms may include:

  • below-normal height for a child’s age
  • one leg or arm being longer than the other
  • pain during exercise
  • soreness of nearby muscles

Hereditary multiple exostoses (HME)

When more than one abnormal bone growth (exostosis) appears, the cause is usually hereditary. HME is a rare condition that usually shows up in childhood. Sometimes it’s visible to the eye as a lump or protrusion of a bone.

This form of exostosis usually occurs around the long bones of the leg. It sometimes occurs in the upper arm or shoulder blade.

Two other names for this condition are multiple osteochondromatosis and diaphyseal aclasis.

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