Lipoma
A lipoma is a common benign tumour of adipose tissue, usually found in the subcutaneous tissue. It classically presents as a soft, mobile, slow-growing, well-circumscribed subcutaneous lump.
This updated UKMLA guide
Epidemiology
Lipoma is the most common mesenchymal tumour (~1 in 1,000 people develop a lipoma at some point in their lifetime) [Ref]
Slightly more common in males [Ref]
Most common in 40-60 y/o [Ref]
Causes and Risk Factors
The exact underlying cause is unknown
- Potential association between trauma and lipoma
- Genetic factors may play a role
Clinical Features and Diagnosis
Lipoma is primarily a clinical diagnosis (for suspicious masses, radiological imaging may be necessary – see the red flag section below)
| Distribution and location |
|
| Symptoms | Often asymptomatic
Unless large lipomas compress nearby structures and cause pain |
| Appearance and on examination |
The overlying skin surface should be normal |
A lipoma is classically described as a soft, non-tender, mobile subcutaneous mass with well-defined borders that is slow-growing.
Red Flags and When to Refer
A lipoma is benign, but the most important differential diagnosis to exclude is a soft tissue sarcoma (esp. liposarcoma)
The key red flag outlined by NICE is an unexplained lump that is increasing in size (esp. if rapidly) [Ref]
- Perform an urgent ultrasound (very urgent <48 hours in children)
- If the ultrasound findings are suggestive of soft tissue sarcoma or uncertain but clinical concern remains → consider referral
- Adults → suspected cancer pathway referral
- Children → very-urgent referral (<48 hours)
Some other textbook red flags for liposarcoma that are not mentioned by NICE: [Ref1][Ref2]
- Superficial mass that is >5 cm in size
- Any deep-seated mass
- Painful mass
- Rapidly increasing in size
- Skin changes overlying the mass (e.g. discolouration, ulceration)
- Immobile (fixed to underlying tissue)
- Firm or hard consistency
Management
Most lipomas require no treatment
Surgical excision can be used for:
- Symptomatic lesions (e.g. pain or discomfort, functional impairment, neurological symptoms), or
- Enlarging lesions on sites that are likely to become symptomatic