The porphyrias are a group of mainly inherited disorders of heme biosynthesis where accumulation of porphyrins and/or porphyrin precursors gives rise to 2 types of clinical presentation: cutaneous photosensitivity and/or acute neurovisceral attacks. The cutaneous porphyrias present with either bullous skin fragility or nonbullous acute photosensitivity. This review discusses the epidemiology, pathogenesis, clinical presentation, laboratory diagnosis, complications, and current approach to porphyria management. Although focusing mainly on their dermatological aspects, the article also covers the management of acute porphyria, which by virtue of its association with variegate porphyria and hereditary coproporphyria, may become the responsibility of the clinical dermatologist.
Key points
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Active cutaneous porphyria requires circulating porphyrins to reach the skin; therefore, a normal plasma porphyrin fluorescence emission screen excludes active cutaneous porphyria.
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The diagnosis of erythropoietic protoporphyria (EPP)/X-linked dominant protoporphyria (XLDPP) is suggested by the history of acute pain within minutes of sun exposure; physical signs are frequently absent but prolonged exposure can lead to erythema and edema, and an EDTA-preserved blood sample is essential to confirm the diagnosis.
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Lifelong effective photoprotection is key in the management of cutaneous porphyria.
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Porphyria cutanea tarda (PCT) can be treated with low-dose hydroxychloroquine or with phlebotomy in those patients with hemochromatosis and overt iron overload.
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All patients with variegate porphyria (VP) or hereditary coproporphyria (HCP) should be considered susceptible to acute attacks and advised on the known triggers, in particular, prescription medications and the requirement for lifelong vigilance.
Introduction
The porphyrias are a group of mainly inherited disorders of heme biosynthesis where reduced activity of a pathway enzyme, or in 1 case a gain of function, results in accumulation of porphyrins and/or porphyrin precursors, giving rise to 2 types of clinical presentation: cutaneous photosensitivity and/or acute neurovisceral attacks ( Table 1 ). Skin problems related to circulating porphyrins are a feature of 6 of the 8 main types of porphyrias and fall into 2 categories. Acute painful photosensitivity due to the accumulation and circulation of excess protoporphyrin is associated with EPP and XLDPP, recently renamed X-linked EPP. Skin damage manifesting as fragility and blistering characterizes the bullous porphyrias, which comprise congenital erythropoietic porphyria (CEP) and PCT. Two of the acute porphyrias, HCP and VP, can also present with skin fragility, alone or in association with acute attacks.
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