Lipoma
Soft, rubbery fatty lump under the skin. The most common soft tissue tumor - almost always harmless.
What to look for
Side-by-side comparison
Normal tissue
No lumps under skin
Lipoma
Soft, rubbery, mobile lump
A lipoma is a slow-growing, soft, rubbery, movable lump located just beneath the skin, composed of mature fat cells enclosed in a thin fibrous capsule. Lipomas are the most common soft tissue tumor, affecting approximately 1 in 1,000 people.
They feel distinctly different from other lumps: soft (not firm), rubbery (not hard), freely mobile under the skin (you can push them around), and usually painless. Most lipomas are 2-5cm but can occasionally grow larger.
Lipomas can occur anywhere with subcutaneous fat but are most common on the trunk, upper arms, upper thighs, and neck. They can be solitary or multiple (familial multiple lipomatosis). They almost never undergo malignant transformation.
The main clinical concern is distinguishing lipoma from liposarcoma - a rare malignancy of fat tissue. Red flags for liposarcoma include: deep location (below the muscle fascia), rapid growth, large size (>5cm), firmness rather than softness, fixation to underlying tissue, and pain. Any deep or rapidly growing fatty mass warrants imaging.
Quick self-check
Does this look like lipoma? Answer 2 questions.
Is the lump soft, rubbery, and moves easily when pushed?
Has it been growing slowly or stayed the same size?
Risk factors
- Age 40-60 (most common age at presentation)
- Genetic predisposition (can run in families)
- Obesity does not cause lipomas despite both involving fat
When to see a dermatologist
- ⚠A lump that is hard, firm, or fixed rather than soft and mobile
- ⚠Rapid growth of a previously stable fatty lump
- ⚠A deep lump larger than 5cm
- ⚠Any lump that is painful at rest
Often confused with
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Full ABCDE check →Frequently asked questions
Can a lipoma become cancer?
Malignant transformation of a lipoma is extremely rare - so rare that many pathologists question whether it occurs at all. Liposarcoma is a separate entity that develops independently, not from pre-existing lipomas.
When should a lipoma be removed?
Only if it causes discomfort, restricts movement, is cosmetically bothersome, or if there is diagnostic uncertainty. Most lipomas can be safely monitored without treatment.