Xanthoma

Localized or generalized deposits of lipid-laden macrophages (foam cells) in the skin, subcutaneous tissue, tendons, or internal organs

Aetiology

  • Primary (genetic) hyperlipoproteinemia
  • Secondary causes:
    • Diabetes mellitus
    • Hypothyroidism
    • Nephrotic syndrome
    • Primary biliary cholangitis
    • Obesity
    • Drugs (retinoids, corticosteroids, estrogens)

Pathophysiology

  • Elevated plasma lipoproteins leak through capillary walls
  • Lipids are phagocytosed by macrophages
  • Accumulation of foam cells in the dermis or tendons → xanthoma formation

Clinical presentation

1. Xanthelasma Palpebrarum

  • Most common type
  • Yellow, soft plaques on eyelids (medial canthus)
  • May occur with normal lipid levels
  • Associated with cardiovascular risk
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2. Eruptive Xanthoma

  • Sudden onset of multiple yellow papules with erythematous halo
  • Common on buttocks, shoulders, extensor surfaces
  • Associated with severe hypertriglyceridemia
  • May be accompanied by pancreatitis
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3. Tuberous Xanthoma

  • Firm, painless nodules or plaques
  • Located on elbows, knees, buttocks
  • Associated with Type III hyperlipoproteinemia
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4. Tendinous Xanthoma

  • Subcutaneous nodules over tendons
    • Achilles tendon
    • Extensor tendons of hands
  • Strongly associated with familial hypercholesterolemia
  • High risk of premature cardiovascular disease

5. Plane Xanthoma

  • Flat, yellow-orange plaques
  • May be localized or generalized
  • Can be associated with paraproteinemia or hematologic malignancy

Investigations

Histopathology

  • Foam cells in dermis
  • Cholesterol clefts may be seen
  • No epidermal involvement
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Management

  • Usually complete surgical excision (+ biopsy) with a wide margin
  • May be treated topically if smaller and not invasive