Porphyria cutanea tarda

PCT is the most common of the porphyrias. It is most common in middle-aged men and in women associated with oestrogen therapy. Incidence of PCT has not been accurately determined and differs by geographical area, probably reflecting geographical variations in the prevalence of susceptibility factors. Prevalence in the US has been estimated to be 1 in 25,000, and yearly incidence in the UK has been estimated at 2 to 5 per 1 million.[1]Phillips JD, Anderson KE. The porphyrias (Chapter 59). In: Kaushansky K, Lichtman MA, Prchal JT, et al, eds. Williams Hematology, 10th ed. New York, NY: McGraw-Hill;2020:961-86.

A massive outbreak of PCT in the 1950s in Turkey resulted from ingestion of seed wheat treated with hexachlorobenzene as a fungicide. A few much smaller outbreaks have been related to occupational or environmental exposure to other halogenated polycyclic aromatic hydrocarbons.

PCT is rare in childhood. Homozygous familial (type 2) PCT, which is known as hepatoerythropoietic porphyria, is rare, usually presents in early childhood, and resembles congenital erythropoietic porphyria clinically.[1]Phillips JD, Anderson KE. The porphyrias (Chapter 59). In: Kaushansky K, Lichtman MA, Prchal JT, et al, eds. Williams Hematology, 10th ed. New York, NY: McGraw-Hill;2020:961-86.