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 to lipoma is based on PCDS guidance, which covers causes, signs and symptoms, diagnosis, and management.
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