ConditionSkin, hair & nails
Lipoma (Fatty Lump)
A lipoma is a slow-growing, benign lump of fat cells that forms just under the skin. It feels soft and rubbery, moves easily under the fingers and is usually painless. Lipomas are very common, typically appear between ages 40 and 60, and most often develop on the shoulders, back, neck, arms (including near the elbow), trunk and thighs. They are not cancer and rarely cause problems. A lump that is hard, painful, growing fast or larger than about 5 cm (2 in) should be checked.
Also called: Fatty tumor, fatty lump, adipose tumor, benign lipomatous tumor
At a glance
- What it is
- A benign, soft lump of fat cells under the skin.
- How common
- Very common; about 1 in 100 people; many have more than one.
- Typical features
- Soft, doughy, movable, painless, slow-growing, usually under 5 cm.
- Common sites
- Shoulders, back, neck, upper arms, forearms, trunk and thighs.
- Warning signs
- Rapid growth, hard or fixed lump, pain, deep location, size over 5 cm.
- Treatment
- None needed unless bothersome; surgical removal or liposuction if wanted.
When to get help
See a doctor within a day or two
- A lump that is growing quickly over weeks
- A lump that is hard, fixed to deeper tissue or painful at rest
- A lump deep in a muscle, or larger than about 5 cm (2 in)
- A lump that returns quickly after removal
Book a routine appointment
- Any new lump you are unsure about
- A soft lump that has become uncomfortable, presses on a nerve or is in an awkward place
- Many lumps appearing, especially with a family history of similar lumps or bowel polyps
- A lump that is red, warm or tender (more typical of a cyst or infection)
Usually safe to manage at home
- A long-standing, soft, movable, painless lump under 5 cm that has not changed, already checked by a doctor
What a lipoma feels like
- soft, doughy or rubbery
- moves easily when pressed
- smooth edges, often round or oval
- usually 1 to 5 cm, sometimes larger
- painless, unless it presses on a nerve or contains many blood vessels (angiolipoma)
- normal skin color over it
Lipoma on the arm or near the elbow
The arms are a common site. A soft lump on the upper arm, forearm or near the elbow that moves under the skin is often a lipoma. Other lumps around the elbow include:
- olecranon bursitis: a soft, fluid-filled swelling right over the point of the elbow
- rheumatoid nodules or gout tophi: firm lumps on the forearm near the elbow
- ganglion or epidermoid cysts
A doctor can usually tell these apart by examination, sometimes with an ultrasound.
Causes and risk factors
The exact cause is unknown. Factors include:
- genetics: lipomas often run in families
- age: most appear between 40 and 60
- minor injury: some appear after a blow to the area
- inherited conditions causing multiple lipomas: familial multiple lipomatosis, Gardner syndrome, Cowden syndrome
- Dercum disease: many painful lipomas, mostly in women
- Madelung disease: symmetrical fatty deposits around the neck and shoulders, linked to heavy alcohol use
Lipoma vs other lumps
| Lump | Key features |
|---|---|
| Lipoma | Soft, movable, painless, slow-growing |
| Epidermoid (sebaceous) cyst | Firmer, often with a central dark pore, can become red, inflamed and drain cheesy material |
| Dermatofibroma | Small, firm, skin-colored or brown bump that dimples when pinched |
| Swollen lymph node | Firm, in the neck, armpit or groin, often with infection |
| Liposarcoma and other sarcomas | Usually deep, firm, larger than 5 cm, growing, sometimes painful |
When to worry: lipoma or sarcoma?
Soft tissue sarcomas are rare cancers that can resemble lipomas. Doctors use these warning signs to decide on further tests:
- size larger than about 5 cm
- growing in size
- deep to the muscle layer
- hard or fixed
- painful
- recurring after removal
Diagnosis
Most lipomas are diagnosed by examination. Further tests are used when the lump is atypical:
- Ultrasound: confirms a fatty lump and its depth.
- MRI: for large, deep or unusual lumps.
- Biopsy: if sarcoma is a concern, ideally planned with a sarcoma specialist team.
Treatment
Lipomas do not need treatment unless they cause symptoms or you want them removed.
- Surgical excision: the most effective option. Done under local anesthetic in the office or day surgery. The lipoma is removed through a small incision, usually with low recurrence.
- Liposuction: for larger lipomas, leaves smaller scars but has a higher chance of recurrence.
- Steroid injections: can shrink small lipomas but rarely remove them.
The removed tissue is usually sent to a lab to confirm the diagnosis.
Do not try to remove or squeeze a lipoma yourself; it is not a pus-filled cyst and will not drain.
Outlook
Lipomas are harmless and do not turn into cancer. They may slowly grow but usually stay stable for years. Removal is curative in most cases, though new lipomas can appear elsewhere.
Frequently asked questions
What is a lipoma?
A lipoma is a benign lump of fat cells under the skin. It is soft, moves easily and is usually painless. Lipomas are very common, harmless and usually appear in adults between 40 and 60 on the shoulders, back, arms, neck or thighs.
How can I tell a lipoma from a cyst?
A lipoma is soft, doughy and moves easily, with no opening on the skin. A cyst is usually firmer, may have a central dark pore, and can become red, painful and drain material when inflamed. A doctor can confirm with an examination or ultrasound.
Should I worry about a lipoma on my arm?
Usually not. Most lumps on the arm that are soft, movable and painless are lipomas. See a doctor if the lump is larger than about 5 cm, growing, hard, fixed, painful or deep, so it can be checked to rule out rare cancers.
Can a lipoma go away on its own?
Lipomas rarely disappear on their own. They usually stay the same size or grow very slowly. Since they are harmless, many people leave them alone. Surgical removal is the only reliable way to get rid of one.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Dermatology: Lipoma
- MedlinePlus: Lipoma
- NHS: Lipoma
- American Academy of Family Physicians: Diagnosis and management of common benign skin tumors
- American Cancer Society: Soft tissue sarcoma signs and symptoms