What is a lipoma?

A lipoma is a knot of fatty tissue that is usually found just below the skin (subcutaneous). Lipomas can occur almost anywhere on the body, but are most commonly found on the trunk, shoulders, neck, and armpits. Lipomas can rarely form in muscles and internal organs.

A lipoma can be described as a rubbery bulge that feels like it can move. Lipomas tend to grow slowly, often over a period of months or years. They are usually small (usually less than 2 inches across). Sometimes larger lipomas do occur, with some reaching almost 8 inches across.

Lipomas are fairly common, occurring in 1 in every 1,000 people. People with a lipoma usually have only 1, though about 20% of those affected can have several.

Lipomas affect all age groups and can even be present at birth; however, they usually form in people who are between the ages of 40 and 60.

Are lipomas cancerous?

A lipoma is nearly always benign, meaning it is not cancerous and will not develop into cancer. There is a very rare form of cancer known as liposarcoma that occurs within fatty tissue and may look like a deep lipoma. A lipoma that grows quickly or is painful should be checked out by a doctor, and may need a biopsy.

What causes lipomas?

The causes of a lipoma are unknown. It is possible that they are caused by a physical trauma. However, it is unclear whether the trauma causes a lipoma to form, or if the lipoma is discovered simply as a result of medical attention to that area of the body.

In other cases, genetic (inherited) conditions such as Gardner syndrome and hereditary multiple lipomatosis cause a person to have several lipomas. Another rare condition, Madelung's disease, is seen mostly in men who drink a lot of alcohol.

What are the symptoms of lipomas?

Lipomas rarely cause pain, and so most people have no symptoms. However, a person with a lipoma can have some pain if the lipoma presses on the nerves or has some blood vessels running through it.

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