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Patient Awareness · Benign Soft Tissue Tumours

Lipoma & Lipomatous Tumours

A soft, mobile lump of fat under the skin is the commonest benign soft-tissue tumour of adult life — harmless in the vast majority of people, but worth checking when it grows, hurts or feels deep.

Overview

What is a lipoma?

A lipoma is a benign tumour of mature fat cells. It sits in the fat layer beneath the skin, feels soft and rubbery, slides easily under the fingers and grows very slowly. Lipomas account for up to 16% of all benign soft-tissue tumours and are seen most often in adults aged 40–60 years. Most cause no symptoms at all unless they press on a nearby nerve or structure.1

Key point: a lipoma cannot turn into cancer. The reason we still examine fatty lumps carefully is that a rare fatty cancer — a liposarcoma — can look similar from the outside, and the two are told apart by imaging rather than by feel.5
Who's Affected

Who gets lipomas and where do they occur?

Age
40–60 yrs

Typical age at presentation

Frequency
Up to 16%

Of all benign soft-tissue tumours

Usual size
1–3 cm

Larger if left untreated for years

  • • Subcutaneous: trunk, neck, shoulders and the upper arms or thighs — by far the commonest
  • • Intramuscular: less often, within the muscle itself
  • • Retroperitoneal: uncommon, deep inside the abdomen, and always needs specialist imaging
  • • Multiple lipomas tend to cluster over the torso and upper limbs

1,4

Causes

What causes a lipoma?

The precise cause is not known. What we do know is that many lipomas carry a rearrangement of chromosome 12q13-15 involving the HMGA2 gene, a change that arises in the fat cells themselves rather than being inherited in most people.2

Possible contributors
  • • Minor injury to the area has been suggested as a trigger
  • • Excess body weight is associated but not proven as a cause
  • • Some families carry an inherited tendency to multiple lipomas
  • • No definite, modifiable risk factor has been established

2,3

Warning Signs

When should I get a fatty lump checked?

A typical lipoma is a painless, soft, rubbery mass that moves freely under the skin. The features below are the ones that take a lump out of the "typical" category and make specialist review worthwhile.1

Rapid growth
Enlarging beyond 5 cm within about six months.
Pain or tenderness
Discomfort over the lump, or restriction of movement.
Deep, firm or fixed
A mass that does not slide freely, or sits below the muscle layer.
Skin change or inflammation
Redness, warmth, ulceration or change in the overlying skin.
Why these features matter

Each one is also a feature of an atypical lipomatous tumour or a liposarcoma. Recognising them early means the lump is imaged, and if needed biopsied, before any operation — which is what keeps treatment simple and complete.5

Diagnosis

How is a lipoma diagnosed?

Examination and ultrasound
  • • A classic superficial lipoma is often diagnosed on examination alone — soft, mobile and painless
  • • Ultrasound shows a uniform, hyperechoic mass with a thin capsule
  • • Ultrasound is quick, radiation-free and ideal for small, superficial lumps
  • • Measurements are recorded so any future growth can be compared objectively
MRI and biopsy
  • • MRI shows pure fat signal on T1-weighted images without contrast enhancement
  • • Thick septa, nodules or enhancement point away from a simple lipoma
  • • A planned core biopsy is reserved for deep, large or atypical lesions to exclude liposarcoma
  • • Deep and intramuscular lesions are always imaged before removal
Where a fatty mass looks anything other than straightforward, the diagnosis is settled with a properly planned biopsy and reviewed through specialist diagnostic guidance before any surgery is arranged.1,5
Treatment

How are lipomas and lipomatosis treated?

Most lipomas need nothing more than reassurance. Treatment is offered when the lump causes symptoms, interferes with function, or troubles the patient cosmetically.1,3

1. Observation
  • • The right choice for a small, painless, typical lipoma
  • • No imaging needed once the diagnosis is clinically clear
  • • Return for review if the lump grows, hardens or becomes painful

1

2. Surgical excision
  • • For symptomatic, painful or cosmetically concerning lesions
  • • The lipoma is removed complete with its capsule
  • • Recurrence about 5% per treated site
  • • Small superficial lesions can often be removed through a minimally invasive approach

1,3

3. Liposuction
  • • Useful in diffuse lipomatosis where many lesions coexist
  • • Minimises scarring across a wide area
  • • Higher chance of residual fat than with formal excision

3

4. Medical and supportive care
  • • Evidence for drug treatment is limited
  • • Weight management and metabolic control may help in Dercum's disease
  • • Pain management matters in painful lipomatosis

6

What are multiple lipomatous tumours?

Two or more lipomas together are described as lipomatosis. Several recognised patterns exist:

  • • Familial multiple lipomatosis — inherited in an autosomal dominant pattern, with numerous lipomas under the skin
  • • Dercum’s disease — painful lipomatosis, most often in women with obesity, and associated with metabolic disturbance
  • • Madelung’s disease — symmetrical fatty deposits around the neck and shoulders, linked with alcohol use and mitochondrial defects

3,6

Angiolipoma — the tender fatty lump

What it is and who gets it
  • • A variant of lipoma containing proliferating small blood vessels
  • • This vascular component is what makes it tender rather than painless
  • • Usually young adults, occasionally running in families
  • • Typical sites: forearms, trunk and back, in the fat under the skin
How it is diagnosed and treated
  • • MRI shows a fat-signal mass with internal vascular channels
  • • Under the microscope: mature fat cells interspersed with vessels
  • • Surgical excision is curative
  • • Recurrence after complete removal is very low

7

Outlook

What is my outlook after treatment?

Malignant potential
None
A true lipoma does not become cancer
Recurrence after excision
~5%
Per treated site
Angiolipoma recurrence
Very low
After complete removal

For a single lipoma the outlook is excellent. Multiple lipomatosis behaves more like a long-term condition that may need periodic treatment, and how well a patient does depends on the number of lesions and how effectively symptoms are controlled.1,3

Decision Guide

Which approach is right for me?

Observation if…
  • • The lump is small, soft, mobile and painless
  • • It has been unchanged for months or years
  • • It causes no functional or cosmetic concern
Excision if…
  • • The lipoma is painful or presses on a nerve
  • • It limits movement or catches on clothing
  • • It is cosmetically troubling, or you simply want it gone
Imaging first if…
  • • The lump is deep, fixed or larger than 5 cm
  • • It has grown noticeably in the last six months
  • • It sits within muscle or inside the abdomen
Follow-up

What follow-up will I need?

Surveillance plan
  • • Annual clinical examination is sufficient for most patients
  • • Imaging is repeated if a lesion changes rapidly or sits deep
  • • After excision, the wound is reviewed and the specimen result explained
  • • Any new lump is examined rather than assumed to be another lipoma

1

Living with multiple lipomas
  • • Treatment is staged over time rather than done all at once
  • • Weight and metabolic control can help in Dercum’s disease
  • • Reducing alcohol intake matters in Madelung’s disease
  • • Normal activity and exercise are encouraged throughout

3,6

Next Steps

Next Steps — Talk to a Specialist

Book an AppointmentContact the clinic
Sources

References

  1. 1Lipoma of the soft tissue: clinical presentation, imaging and management — review article. ScienceDirect, 2025.
  2. 2Genetic alterations of chromosome 12q13-15 (HMGA2) in benign lipomatous tumours. ScienceDirect / Pathology - Research and Practice.
  3. 3Multiple symmetric lipomatosis and familial multiple lipomatosis: clinical spectrum and management. NCBI PMC.
  4. 4Kransdorf MJ, Bancroft LW. Benign soft tissue tumors: lipoma and variants — imaging review. PubMed.
  5. 5Imaging characteristics distinguishing lipoma from atypical lipomatous tumour / well-differentiated liposarcoma. NCBI PMC.
  6. 6Hansson E, Svensson H, Brorson H. Review of Dercum's disease and proposal of diagnostic criteria and treatment. NCBI PMC.
  7. 7Angiolipoma: clinical features, imaging and surgical outcomes — case series. NCBI PMC.
Medical Disclaimer

Important Notice: This information is provided for educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. It should not be used to diagnose or treat any health condition.

Always seek the advice of a qualified orthopaedic oncologist or healthcare provider with any questions about a fatty lump, lipoma or any other medical condition. Never disregard professional medical advice or delay seeking it because of something you have read here.

Treatment varies with the site, size and depth of the lesion, the symptoms it causes and the structures around it. Individual outcomes differ, and decisions are best made after a specialist assessment.

The Orthoncology Clinic is committed to providing current, evidence-based information while emphasising multidisciplinary collaboration for complex tumour management.