Porphyria cutanea tarda

Presents with blistering and crusted skin lesions on the back of hands and other sun-exposed areas of the body. Other common features include skin fragility, with minor trauma causing blister formation, hypertrichosis, skin hyperpigmentation, and dark or reddish urine.

Factors that contribute to susceptibility include alcohol use, smoking, hepatitis C, HIV, iron overload, hereditary haemochromatosis gene mutations, oestrogen use, and uroporphyrinogen decarboxylase (UROD) mutations.

Results from an acquired, substantial deficiency of UROD in the liver.

Diagnosis is established by finding substantial increases in porphyrins in urine or plasma.

Treatment includes repeated phlebotomy or low-dose hydroxychloroquine or chloroquine; remission can usually be achieved within 6 months.

Most common of the porphyrias.

Porphyria cutanea tarda (PCT) is a blistering cutaneous condition caused by a substantial deficiency of hepatic uroporphyrinogen decarboxylase, the fifth enzyme in the haem biosynthetic pathway. Substrates for the deficient enzyme, which are porphyrinogens (reduced porphyrins), accumulate, are oxidised to porphyrins, transported to the skin, and cause photosensitivity.[1]Phillips JD, Andersen KE. The porphyrias (Chapter 58). In: Kaushansky K, Lichtman MA, Beutler E, et al, eds. Williams Hematology, 9th ed. New York, NY: McGraw-Hill;2016: 889-914. PCT is usually associated with liver cell damage.