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.
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.
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.
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.
In most cases, doctors can diagnose a lipoma with a simple physical examination. However, if the lipoma is large and/or painful, the doctor may order a test to confirm that the lump is not cancerous. These tests may include a biopsy, computed tomography (CT scan), or magnetic resonance imaging (MRI).
A biopsy is a procedure in which a small piece of the fatty tissue is removed from the lipoma so it can be examined under a microscope for signs of cancer. An MRI uses a magnet, radio waves, and a computer to take a series of very clear, detailed pictures. Like an MRI, a CT scan (or CAT scan) is a procedure that makes a series of detailed pictures, taken from different angles.
Once a lipoma is diagnosed, your doctor will discuss whether treatment is needed and what the options are.
In many cases, lipomas do not need to be treated. Instead, your doctor may simply recommend watching the lipoma on a regular basis. Sometimes a patient may choose to have the lipoma removed if there is concern about its location and how it affects the person’s appearance. (This procedure may not be covered by health insurance.)
Occasionally, a lipoma causes pain or affects muscle development and needs to be removed. Lipomas are usually self-contained, meaning they do not invade (move into) the surrounding tissue. Therefore, it is usually possible for the doctor to make a small incision (cut) in the skin and then either squeeze out the lipoma, or use liposuction.
During the liposuction procedure, an incision is made in the lipoma, and a thin, hollow tube called a cannula is inserted into the incision. The cannula is then moved back and forth to loosen the fat, which is vacuumed up through the tube.
Liposuction can be useful for larger lipomas, but the procedure is associated with a higher rate of recurrence (the lipoma grows back). Procedures to remove lipomas are usually done under local anesthesia, and patients go home the same day.
The outlook for people with lipomas is extremely positive. Because lipomas are generally harmless and cause no discomfort, they do not affect a person's quality of life. Lipomas do not increase the risk of other diseases, and people who choose to have their lipomas removed for cosmetic reasons usually have limited scarring.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 03/18/2016