Lipoma
A lipoma is a benign, freely mobile subcutaneous fat tumor that is diagnosed clinically on the basis of a soft, painless, slowly growing mass and managed with observation unless the lesion is symptomatic, atypical, or the patient requests removal, in which case elective excision is curative. Features that break the typical pattern, size 5 cm or larger, deep or fascial fixation, rapid growth, or unexplained pain, should trigger imaging and specialist evaluation to exclude liposarcoma rather than routine removal.
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What this article covers
- Overview
Benign fat tumor: a lipoma is a benign neoplasm of mature adipose tissue that forms a soft, encapsulated subcutaneous mass; its malignant counterpart is liposarcoma.
- Epidemiology
Common soft-tissue mass: lipomas are among the more frequently encountered benign subcutaneous masses in adults presenting for evaluation of a lump.
- Risk factors
Age 40 to 60 years: most lipomas first become apparent in this age window.
- Pathophysiology
Mature adipocyte proliferation: the tumor arises from the same mesenchymal lineage as normal fat, producing a mass histologically indistinguishable from mature adipose tissue and explaining its soft…
- Clinical features
Defining triad: the diagnostic pattern is a soft, freely mobile, painless subcutaneous mass; a lesion with all three features can be diagnosed clinically without further testing.
- Differential diagnosis
Epidermoid (epidermal inclusion) cyst: presents as a mobile dermal or subcutaneous nodule but with a central punctum, a feature absent in a lipoma.
- Diagnosis
Clinical pearl. A subcutaneous mass that is soft, mobile, and painless is almost always a lipoma; a mass that is large, fixed, deep, rapidly growing, or painful is not, and deserves imaging before it is casually excised in clinic.
- Management
First step, observe the typical lesion: a stable, asymptomatic, clinically typical superficial lipoma can be observed without intervention.
- Complications
Recurrence: local recurrence after complete excision is uncommon and should trigger reconsideration of the diagnosis if it is rapid or repeated, since true lipomas rarely recur once fully excised.
- Prognosis
Benign course: simple lipomas are benign and do not ordinarily transform into liposarcoma.
- Prevention
No primary prevention: there is no described modifiable risk factor or screening interval for sporadic lipoma; surveillance focuses on atypical features rather than prevention of the tumor itself.
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