Angiolipoma
Painful subcutaneous lipoma · angiolipoma
Angiolipomas are benign adipocytic tumours containing mature adipocytes intermixed with a prominent vascular network. They are common, particularly in young men, presenting as multiple tender subcutaneous nodules on the trunk and limbs. Their distinctive feature — pain on palpation — distinguishes them from ordinary lipomas. Familial angiolipomatosis is a recognised autosomal-dominant phenotype. Management is conservative or excisional based on symptoms.
Epidemiology
- Adults 20-50 years; male predominance (~3:1).
- Multiple in ~70%; solitary in 30%.
- Familial angiolipomatosis: autosomal-dominant; numerous angiolipomas; family clustering.
- Sites: forearms (commonest), trunk, upper arms, thighs.
Pathology
- Encapsulated subcutaneous lesion.
- Mixture of mature adipocytes and small thin-walled blood vessels with fibrin thrombi (pathognomonic histological clue).
- Vascular proportion variable (5-100%):
- Predominant fat with scattered vessels → typical angiolipoma.
- Predominant vessels with sparse fat → cellular angiolipoma (more concerning histologically but still benign).
- No atypia, no mitoses, no necrosis.
- IHC: CD34+ vessels, S100+ adipocytes; benign Ki-67.
- Molecular: distinct from spindle cell lipoma (no 13q14 deletion).
Clinical features
- Multiple small (0.5-2 cm) soft mobile subcutaneous nodules.
- Painful on palpation — the hallmark distinguishing from ordinary lipoma.
- Pain may radiate; can be spontaneous in some lesions.
- Slow growth.
- Overlying skin normal.
- Sites: forearms, upper arms, anterior trunk.
- Family history common in familial angiolipomatosis.
Differentials
- Ordinary lipoma — typically painless.
- Spindle cell / pleomorphic lipoma — posterior neck / shoulder; older male.
- Glomus tumour / glomangioma — paroxysmal pain, cold sensitivity, point tenderness.
- Leiomyoma — painful clustered nodules (Reed syndrome / HLRCC).
- Schwannoma / neurofibroma — pain on tinel sign; nerve distribution.
- Eccrine spiradenoma / eccrine angiomatous hamartoma — painful eccrine origin.
- Dercum disease (adiposis dolorosa) — painful fatty masses, obese postmenopausal women.
- Granular cell tumour.
Mnemonic for painful subcutaneous tumours: BANGLE — Blue rubber bleb naevus, Angiolipoma, Neuroma, Glomus, Leiomyoma, Eccrine spiradenoma. (Or LEND AN EGG.)
Management
- Clinical diagnosis usually adequate with classic painful subcutaneous nodules in a young male.
- Conservative: reassurance; analgesia if needed (NSAIDs).
- Excision: simple excision for symptomatic / cosmetically prominent lesions; usually well-circumscribed, easy dissection.
- Recurrence rare.
- Cellular angiolipoma: complete excision; pathology to confirm benign nature.
- Familial angiolipomatosis: counsel about benign nature; surgical removal of symptomatic lesions only.
- No metastatic potential.
References
- Howard WR, Helwig EB. Angiolipoma. Arch Dermatol. 1960;82:924-931.
- Lin JJ, Lin F. Two entities in angiolipoma: a study of 459 cases. Cancer. 1974;34:720-727.
- Sciot R et al. Cytogenetic analysis of subcutaneous angiolipoma: further evidence supporting its difference from ordinary pure lipomas. Am J Surg Pathol. 1997;21:441-444.
- WHO Classification of Tumours Editorial Board. WHO Classification of Soft Tissue and Bone Tumours, 5th ed. Lyon: IARC; 2020.
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