An intramuscular lipoma is a rare noncancerous (benign) tumor that forms deep inside a muscle. Tumors that don’t cause symptoms rarely require treatment. Your provider may remove a large intramuscular lipoma that pinches nerves, causes nerve pain or muscle cramps — or forms an unsightly bump under the skin.
An intramuscular lipoma is a rare, noncancerous (benign) tumor. It’s made of yellow fatty tissue that forms inside a muscle. Healthcare providers sometimes call this type of soft tissue tumor a deep-seated lipoma because it forms under the fascia. Fascia is a thin sheet of connective tissue that holds muscles in place.
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You may better understand this condition when you break down the terms:
Intramuscular lipomas are rare, accounting for less than 1% of lipomas. Adults ages 40 to 70 are most likely to develop intramuscular lipomas. But the tumors can affect all ages and genders.
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Up to 15% of people have intramuscular lipomas in more than one muscle, but most people have one tumor in one muscle.
Intramuscular lipomas most commonly form deep within muscles in your:
Certain tumor characteristics determine the type of intramuscular lipoma:
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Experts aren’t sure why some people develop intramuscular lipomas. Potential causes include:
Intramuscular lipomas are slow-growing tumors. They may be smaller than half an inch (1 centimeter) or as large as 10 inches (25 centimeters). Smaller tumors don’t always cause symptoms. When symptoms occur, you may notice swelling (edema) or a soft lump underneath your skin that moves. The lump may feel firm when you contract your muscles. You may also experience muscle cramps or muscle pain.
A medical doctor called an orthopedist diagnoses and treats conditions that affect the musculoskeletal system.
Your healthcare provider relies on imaging scans to diagnose soft tissue tumors. You may get one or more of these tests:
You may also get a needle biopsy to confirm that the tumor isn’t a soft tissue cancer like liposarcoma.
You might not need treatment if the intramuscular lipoma doesn’t cause problems. Your healthcare provider may monitor the tumor for signs of growth or changes.
Your provider may recommend treatment if the tumor causes problems or the biopsy doesn’t clearly determine whether the tumor is benign or cancerous. You may also want treatment if the lump is noticeable, making you self-conscious about your appearance.
Treatment involves surgically removing (excising) the tumor. Infiltrating tumors have a 50% to 80% recurrence rate after surgical removal. Well-defined tumors rarely grow back.
An infiltrating intramuscular lipoma can invade nearby tissues, tendons and muscle. A large tumor may cause a pinched nerve and neuropathy (nerve pain).
Intramuscular lipomas are rare and occur for unknown reasons. There isn’t any way to prevent them.
Most people with intramuscular lipomas don’t need treatment. If the tumor causes pain or other problems, you can have surgery to remove it.
Call your healthcare provider if you experience:
You may want to ask your healthcare provider:
No. There’s no evidence of an intramuscular lipoma ever being anything but benign (not cancerous). A biopsy can help determine whether the tumor is cancerous and confirm a lipoma diagnosis.
A note from Cleveland Clinic
You should contact your healthcare provider anytime you notice changes like a lump or swelling underneath your skin. Often, these lumps are nothing to worry about. Soft tissue tumors like intramuscular lipomas are very rare. And if you have one, it’s reassuring to know that these fatty tumors aren’t cancerous. Most people don’t need treatment. But if the tumor causes pain, cramps or looks unsightly, you can get surgery to remove it.
Last reviewed on 07/29/2022.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy