Porphyria cutanea tarda

Porphyria cutanea tarda (PCT) is a type of longterm porphyria characterised by fragile skin and sore blisters in areas of skin that receive higher levels of exposure to sunlight, such as the face and backs of the hands. These blisters burst easily resulting in erosions, crusts, and superficial ulcers. There is often associated darkened skin color and extra facial hair growth. Healing is typically slow, leading to scarring and milia, while changes such as hair loss, and alterations in nails may also occur. A slightly purplish tint may be seen around the eyes. Scleroderma-like thick skin may develop over fingers, scalp, behind the ears, at the back of the neck, or in the front of the chest. The urine may appear dark. Unlike other porphyrias, PCT does not cause severe illness.

The disorder results from a deficiency of uroporphyrinogen III decarboxylase, used in the production of heme, a vital component of hemoglobin. It is generally divided into three types; familial, non-familial, and acquired. The condition can be related to liver disease and a history of excessive alcohol consumption. It is a recognised complication of hepatitis C. Other associated conditions include type 2 diabetes, metabolic syndrome, HIV, SLE, and haemochromatosis. Smoking, and the use of estrogen in males with prostate cancer and females on combined contraceptive pill may also trigger PCT. Renal dialysis may cause retention of porphyrins and cause PCT.

Tests generally include blood tests; liver function test, kidney function, complete blood count, ferritin, hepatitis B, hepatitis C, HIV, and HbA1C. Other tests may include checking urine for pinky-red fluorescence with Wood's lamp, testing a 24-hour urine for porphyrins, and skin biopsy. Pseudoporphyria may appear similar. PCT may be distinguished from epidermolysis bullosa acquisita by the presence of excess hair. Treatment for PCT focuses on removing all contributing factors, including alcohol, specific medicines, and managing hepatitis C and metabolic syndrome if applicable. Though typical sunscreens may provide limited protection, more effective alternatives are barrier sunscreens. Wearing a hat and gloves can help. Other treatment options include phlebotomy. An alternative is low dose of an anti-malarial treatment. Treating co-existing hepatitis C generally helps. Without removing triggering factors, PCT tends to recur. Recurrence in the year following phlebotomy treatment is not common. Individuals with PCT have a 3.5 times higher risk of developing hepatocellular carcinoma.

PCT is rare, though is the most common subtype of porphyria.