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Updated: Dec 17 2021

Porphyria Cutanea Tarda

  • Snapshot
    • A 25-year-old woman, on oral contraceptives, comes to the dermatologist’s office complaining of a rash on her hands, forearms, and face. On exam, her arms and dorsal hands are covered with oozing erosions and ulcers. Alongside these ulcers are patches of hyperpigmented skin. On questioning, we find that her mother has had similar episodes.
  • Introduction
    • Blistering cutaneous photosensitivity caused by hepatotoxic triggers
    • Autosomal dominant or sporadic defect in heme synthesis
      • deficiency of hepatic uroporphyrinogen decarboxylase
        • accumulation of uroporphyrin 1
    • Recurrent flares triggered by hepatotoxins that upregulate heme/P450 synthesis
      • alcohol and estrogen = most common triggers
      • viral hepatitis
      • HIV
      • iron
    • Associated conditions
      • alcoholism
      • liver disease
      • hemochromatosis
      • chronic hepatitis C
      • oral contraceptives
  • Epidemiology
    • Most common form of porphyria
    • Middle-aged men and women
    • Younger women on oral contraceptives
  • Presentation
    • Skin findings
      • skin fragility
      • erythema, edema, vesicles progressing to non-healing blisters, erosions, ulcers
        • in sun-exposed areas (face, neck, dorsal hands, forearms)
      • hypertrichosis of face
      • hyperpigmentation of skin
      • scleroderma-like plaques
    • Non-skin findings
      • no abdominal pain (as in other porphyrias)
      • red-brown urine (port-wine urine) from porphyrin pigment
  • Evaluation
    • Diagnosis by skin biopsy
      • subepidermal split (bullae)
      • linear, eosinophilic acid-Schifff positive globules ("Caterpillar bodies")
      • direct immunofluorescence
        • deposition of IgG, IgM, C3 in papillary dermis
    • Or diagnosis by urine
      • ↑ urine uroporphyrin levels (2-5x above coproporphyrins)
      • Wood’s lamp
        • distinctive orange-pink color due to ↑ uroporphyrin
    • To monitor
      • LFTs, iron studies, renal function test, HIV, hepatitis serologies
  • Differential Diagnosis
    • Pseudoporphyria (from NSAIDs)
    • Porphyria variegata
    • Acute intermittent porphyria
    • Erythropoietic protoporphyria
      • burning pain, erythema, and swelling develops on skin minutes after sun exposure
      • no scarring or blistering
      • protoporphyrins elevated in plasma and RBCs
      • treatment: limit sun exposure; beta-carotene reduces photosensitivity
  • Treatment
    • Avoid exposures (alcohol, estrogen, primidone, other hepatotoxins)
    • Sunscreen use
    • Iron removal by phlebotomy – first line
      • reduces hepatic iron stores – produces remission
      • if phlebotomy not available, deferoxamine
    • Hydroxychloroquine
      • increases excretion of uroporphyrin
  • Prevention & Complications
    • Prevention
      • avoid triggers
  • Prognosis
    • Complete clinical clearing in between 2 months and 2 years after stopping triggers exposures
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