Porphyria cutanea tarda
In most cases of PCT, even inherited cases, liver toxicity (eg, from alcohol abuse disorder, exogenous estrogen exposure, hepatitis C virus infection, hemochromatosis, other causes of iron overload, or hepatic tumors) causes or exacerbates the effects of the enzymatic deficiency. Uroporphyrins subsequently accumulate in the liver and the skin. In the presence of visible light in the Soret band (400-410 nm) and oxygen, porphyrins release energy, and the resultant reactive oxygen species damage tissues. This manifests clinically as skin fragility, blistering, hypertrichosis, scarring, and sclerodermoid plaques. Photo-onycholysis may be seen. Patients may also notice urine discoloration.
Although historically seen in men due to excessive alcohol consumption, it is also seen in women with liver disease or who take exogenous estrogen. The disease usually begins in middle age, or sooner in those with alcohol use disorder. Higher incidence of PCT is reported in patients with human immunodeficiency virus (HIV); however, the increased incidence may be related to concomitant hepatitis C virus infection, drug-induced hepatotoxicity, or comorbid alcohol and/or smoking abuse.
For more information, see OMIM.
E80.1 – Porphyria cutanea tarda
61860000 – Porphyria cutanea tarda
- Pseudoporphyria secondary to certain drugs (nonsteroidal anti-inflammatory drugs [NSAIDs], vitamin A derivatives, immunosuppressants, and chemotherapeutic agents) – Patients have normal porphyrin levels.
- Variegate porphyria (VP) – May present with skin findings identical to PCT, but patients are also at risk for acute porphyric neurologic crises (not seen in PCT). VP is more common in individuals of South African descent and may be differentiated from PCT by the pattern of porphyrins in urine, plasma, and fecal specimens (ratio of urine uroporphyrin to coproporphyrin is approximately 1:1 in VP but up to 8:1 in PCT).
- Hepatoerythropoietic porphyria – Childhood onset with rare autosomal recessive uroporphyrin decarboxylase deficiency.
- Hereditary coproporphyria
- Hydroa vacciniforme
- Bullous lupus erythematosus
- Drug-induced photosensitive reaction
- Epidermolysis bullosa acquisita
- Acute dermatomyositis
- Polymorphous light eruption
- Contact dermatitis
- Bullous pemphigoid
- Bullous fixed drug eruption
- Bullous arthropod bites
Last Updated: 11/03/2017