Blisters and skin fragility on the back of the hands is typical.

PORPHYRIA CUTANEA TARDA

Porphyria Cutanea Tarda (PCT) is a blistering disease, most common on the back of the hands caused by sun exposure and build up in the blood of porphyrins.

• Both an inherited (AD) and an acquired type have been described. For both types, uroporphyrinogen decarboxylase functional activity is low, and a history of exposure to alcohol, estrogens (e.g. oral contraceptives for women or estrogen for prostate cancer in men) or other liver toxic agent (e.g. drug) may be found.
• In one study, Hepatitis C virus antibodies were found in 79% of patients with acquired PCT and in none with familial PCT. The connection between PCT and Hepatitis C varies tremendously by geographic location. For example, the presence of HC in PCT patients has been reported as follows: Indiana (in the US) 94%, Southern Europe 65%, Australia/New Zealand 20%, Northern Europe 17%.
  
• Hepatocellular carcinoma may cause PCT as a paraneoplastic manifestation. Removing the carcinoma causes resolution of the symptoms.
  
• Mutations causing hemochromatosis are more common in patients with PCT.
• Patients with PCT have an increased mortality, primarily explained by an increased mortality from gastrointestinal diseases and from cancers of the gut, liver/gallbladder, and lungs.

Clinical

Vesicles, milia, erosions and fragile skin occur symmetrically on the dorsa of the hands in porphyria cutanea tarda. Look for hypertrichosis along the forehead. In rare cases, usually when the disease goes for a long time untreated, indurated, sclerodermoid plaques may develop on the trunk. The hematocrit is often elevated.

Differential Diagnosis

Diagnosis is made by measuring urinary porphyrins and excluding VP through measurement of fecal porphyrins. PCT may develop in the setting of renal failure and dialysis. Finally, a bullous dermatosis mimicking PCT (pseudoporphyria) but without elevated porphyrin levels may also occur in dialysis patients. This type may be related to various drugs (e.g. furosemide, nalidixic acid and tetracycline).

Drugs and PCT

So, to clarify, a drug may cause PCT which on workup would show elevated porphyrins. Or, a drug could cause pseudopct which would not show elevated porphyrins. But the clinical picture (e.g. blisters and vesicles on the back of the hands) is the same.

Pathology

• Subepidermal bullae bullae with dermal papillae that arise irregularly from the floor of the bulla (Festooning)
• Dermal blood vessel walls that are thickened and hyalinized
• Dermal sclerosis
• A mild perivascular infiltration of mononuclear cells is present in the upper dermis

DIF shows fluorescence of thickened doughnut-like blood vessels in the upper dermis, reflecting deposition of immunoglobulins and C3, and deposition of immunoglobulins or C3 or both at the dermal-epidermal junction in most cases.

Treatment

• Eliminate any cause/trigger if present (e.g. alcohol, BCP, drug)
• Sun protection
• Hydroxychloroquine
• Phlebotomy

Elimination of any cause/trigger if present (e.g. alcohol, BCP, drug) is important.

Sun protection is key. The action spectrum appears to be primarily in the UVA range so sunscreens with UVA blockage are mandatory. Those often include the metal-containing sunscreens. Some have theorized that even the visible spectrum plays a role. The damage to the skin occurs over months and thus repair will occur over a similar timeframe.

Hydroxychloroquine 100 mg po twice weekly is an excellent treatment option and may be first line. It should be avoided in patients with hepatic or renal dysfunction. Time to remission is about 6 months.

Phlebotomy has been the primary treatment for years, but is expensive, somewhat inconvenient and has the risk of inducing anemia or syncope. A unit of blood is removed every 2-4 weeks to decrease the hematocrit. The CBC should be followed and phlebotomy withheld if the hemoglobin level is < 10 g/dL or the hematocrit level < 33.

For the PCT of renal failure and dialysis, erythropoietin and phlebotomy, deferoxiamine or renal transplantation have been used.

Additional Pictures

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