A lipoma is a slow-growing lump of fat that sits just beneath the skin. It feels soft, rubbery, and moves easily when you press on it with your fingers, almost as if it’s not connected to the skin above. Lipomas are benign, meaning they’re not cancerous, and they affect roughly 1 in every 1,000 people, most commonly between the ages of 40 and 60.
What a Lipoma Looks and Feels Like
Most lipomas are small, typically less than 2 inches (5 centimeters) across. They have a doughy, spongy texture and are usually painless. You’ll most often find them on the neck, shoulders, back, abdomen, arms, or thighs, though they can appear almost anywhere fat tissue exists. They sit in the layer between your skin and the underlying muscle, and because they’re encapsulated in a thin fibrous shell, they tend to feel like a distinct, movable marble under the skin.
Lipomas grow slowly, sometimes over months or years. Many people have them for a long time before noticing, and some never grow large enough to be bothersome at all.
Why Lipomas Form
Lipomas are classified as mesenchymal tumors, meaning they arise from the connective tissue cells that can develop into fat cells. The exact trigger isn’t fully understood, but there are a few known contributing factors.
Genetics plays a clear role. A condition called familial multiple lipomatosis causes clusters of lipomas on the trunk and limbs and runs in families through an autosomal dominant pattern. That means if one of your parents carries the gene variant, you have a 50% chance of inheriting it. Even outside of this specific condition, lipomas tend to cluster in families.
Trauma to an area may also be a trigger. One theory is that an injury causing fat cell death and local inflammation can kick-start lipoma formation at that site. This doesn’t mean every bruise leads to a lipoma, but it may explain why some people develop one in a spot that was previously injured.
When a Lipoma Causes Pain
Standard lipomas are painless, which is part of why many people ignore them. But a subtype called an angiolipoma contains blood vessels mixed in with the fat tissue, and these can be tender or outright painful to the touch. If you have a lump that fits the description of a lipoma but hurts when pressed, an angiolipoma is the likely explanation. These are still benign but may warrant removal simply because of the discomfort.
Lipoma vs. Liposarcoma
The concern most people have when they find a soft lump under their skin is whether it could be cancer. Liposarcoma is a rare malignant tumor that can resemble a lipoma, and distinguishing the two matters.
A few red flags suggest a lump needs closer evaluation: it’s larger than 5 centimeters, it’s deep (below the muscle layer rather than just under the skin), or it’s growing rapidly. Guidelines from major oncology organizations recommend imaging with MRI for any deep mass regardless of size, any surface mass over 5 centimeters, or any mass that’s growing fast.
On imaging, a benign lipoma typically appears as a well-defined, uniform fatty mass with thin internal walls (called septa) that are less than 2 millimeters thick. A liposarcoma, by contrast, tends to show irregular borders, thicker internal walls, or areas that don’t look like pure fat. When imaging alone can’t settle the question, genetic testing on a tissue sample is the gold standard. A specific gene amplification test can distinguish lipomas from liposarcomas with over 97% accuracy.
For the vast majority of small, soft, movable lumps just under the skin, the answer is a straightforward lipoma. But if a lump is large, deep, firm, or changing quickly, getting it checked is worthwhile.
How Lipomas Are Diagnosed
Most lipomas are diagnosed with a simple physical exam. A doctor can often identify one by feel alone: soft, movable, painless, and sitting just under the skin. For lumps that are larger or in unusual locations, imaging helps confirm the diagnosis.
Ultrasound is the typical first step for superficial lumps. A lipoma shows up as a well-defined, bright mass with smooth edges. MRI provides more detail for deeper or larger masses, where a lipoma appears identical to the surrounding body fat on all imaging sequences. CT scans can also identify lipomas by their characteristic low density, consistent with fat.
Biopsy is reserved for cases where imaging raises any doubt about whether the lump is truly benign.
Surgical Removal
Most lipomas don’t need treatment. Removal is typically considered when a lipoma is painful, growing, cosmetically bothersome, or pressing on nearby nerves or structures.
The standard approach is surgical excision, which involves cutting the lipoma out along with its capsule. Because the entire capsule is removed, lipomas rarely come back in the same spot after surgery. New lipomas can develop elsewhere over time, but recurrence at the original site is uncommon.
A variation called minimal excision extraction uses a smaller incision to reduce scarring. Liposuction is another option, using a needle and large syringe to suction out the fatty tissue. Liposuction leaves a smaller scar but may not remove the capsule completely, which can slightly increase the chance of regrowth.
Recovery After Removal
Recovery from lipoma surgery is generally quick. Most people return to normal activities and work the day after the procedure. You can expect some pain at the incision site lasting anywhere from a few days to a couple of weeks. During healing, you’ll want to avoid activities that stretch the incision and stay out of pools, hot tubs, and bathtubs for about two weeks to keep the wound clean and dry.
Scarring and bruising are the main side effects, and both tend to fade over time. The extent of scarring depends on the size of the lipoma and the technique used.
Non-Surgical Options
For people who want to avoid surgery, a couple of alternatives exist, though neither is as definitive as excision.
Steroid injections can shrink small lipomas by causing localized fat breakdown, but they rarely eliminate the lump entirely. They’re sometimes used to reduce a lipoma’s size enough that it’s no longer noticeable.
A newer approach uses deoxycholic acid injections, the same compound approved for reducing fat under the chin. When injected into a lipoma, it disrupts fat cell membranes, triggering inflammation and gradual fat breakdown. The body’s immune cells then clear the released fat over the following weeks. One study of 12 small lipomas showed an average 75% size reduction after one to four treatments. This option works best on smaller, superficial lipomas and is considered off-label use, so availability varies. For larger lipomas, multiple treatment sessions spaced months apart can produce meaningful shrinkage, though complete elimination isn’t guaranteed.