Porphyrias are associated with enzymatic defects in heme biosynthesis. Porphyria cutanea tarda (PCT) is the most common type. Patients have photosensitivity, skin fragility, and characteristic lesions on sun-exposed sites (most common on the dorsal hands and forearms). Typically, the skin is easily traumatized with blisters, erosions, superficial scars, milia, and hypertrichosis. PCT does not cause the life-threatening neurologic attacks associated with the acute porphyrias.
PCT may be induced by ethanol, estrogens, oral contraceptives, infections (hepatitis C and HIV), polychlorinated hydrocarbons, dialysis, and iron overload. Pseudoporphyria, which is clinically indistinguishable from PCT, is associated with dialysis and certain medications (NSAIDs, furosemide, hydrochlorothiazides, and amiodarone, among others).
Management and Disposition
Laboratory diagnostics may begin in the ED with blood chemistries, porphyrin studies (24-hour urinary porphyrins can be ordered), and referral to a dermatologist. Long-term treatment includes phlebotomy and antimalarials (which can induce fatal hepatotoxicity in PCT patients). Discontinue any medications that might initiate PCT or pseudoporphyria.
Porphyria Cutanea Tarda. Blisters and erosions of PCT. (Photo contributor: Selim Suner, MD, MS.)
Consider PCT in a patient with fragile skin with erosions and scarring, but only on sun-exposed skin.
PCT does not have acute attacks of abdominal pain, neurologic deficits, psychosis, or autonomic dysfunction. Variegate porphyria, common in South Africans with Dutch ancestry, does present with the typical skin lesions and acute attacks.
Examination of the urine with a Wood’s lamp may reveal orange-red fluorescence.
Always consider medications (both prescribed and over-the-counter medications) and infections as they can worsen PCT.
Porphyria Cutanea Tarda. The easily traumatized skin and erosions of PCT. (Photo contributor: Alan B. Storrow, MD.)