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Presentation

Cutaneous Porphyrias: Diagnosis, Clinical Features, and New Treatments

Description

The talk reviewed cutaneous porphyrias with emphasis on the two most clinically important forms: porphyria cutanea tarda (PCT) and erythropoietic protoporphyria (EPP). It explained that cutaneous porphyrias cause either blistering/fragility/scarring or painful acute phototoxicity, usually from visible light rather than UV, so sunscreens offer limited protection. PCT, the most common form seen in clinic, typically presents with large fragility blisters on sun-exposed areas, scarring, milia, hypertrichosis, pigmentation changes, or sometimes scleroderma-like changes; it is strongly linked to liver disease, iron overload, alcohol, hepatitis C/HIV, and hemochromatosis. Diagnosis relies on plasma porphyrin scanning plus urine and stool porphyrins by HPLC, while distinguishing PCT from variegate porphyria is important because VP can cause acute, potentially fatal attacks. Management of PCT includes visible-light avoidance, minimizing skin trauma, treating underlying liver disease, avoiding triggers such as alcohol and estrogens, and using venesection or iron chelation when needed, with monitoring for cirrhosis and hepatoma. EPP was described as an inherited childhood-onset visible-light phototoxic disorder with minimal skin findings unless severe; patients may use cold water or towels for relief. Diagnosis uses plasma and red cell porphyrins showing elevated free protoporphyrin, and management focuses on genetic counseling, light protection, vitamin D supplementation, bone health, liver monitoring, and avoiding iron. New treatments highlighted included afamelanotide and other emerging agents. The speaker concluded with a practical diagnostic approach and emphasized keeping cutaneous porphyrias in mind, especially in late-onset cases that may reflect myeloproliferative disease.

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Conclusions

Cutaneous porphyrias are uncommon but important to recognize because they often present subtly and require a structured diagnostic approach.
Visible light, not ultraviolet light, is the main phototriggerr in the cutaneous porphyrias, so standard sunscreens offer only limited protection.
Porphyria cutanea tarda is the most likely cutaneous porphyria to be seen in general dermatology and should prompt evaluation for underlying liver disease and iron overload.
A plasma porphyrin scan is a highly sensitive and specific first-line test, but confirmation still requires targeted urine, stool, and/or red cell porphyrin studies depending on the suspected subtype.
PCT should trigger investigation for causes such as alcohol excess, hepatitis C or B, HIV, haemochromatosis, and other liver disorders because treatment of the underlying liver disease is central to care.
Variegate porphyria can mimic PCT clinically but is distinguished by different porphyrin patterns and the potential for acute neurovisceral attacks, making correct classification essential.
Erythropoietic protoporphyria usually begins in childhood with severe pain on visible-light exposure and often minimal visible rash, so a high index of suspicion is needed.
EPP can lead to significant systemic complications including gallstones, cholestatic liver disease, vitamin D deficiency, and bone loss, so ongoing liver and bone monitoring is important.
Management of cutaneous porphyrias requires both skin protection and disease-specific treatment, with avoidance of triggers, reduction of iron overload where relevant, and careful follow-up.
New therapies, especially afamelanotide and other emerging agents, are improving quality of life for patients with EPP and reflect a rapidly advancing treatment landscape.

Langendonk JG et al. N Engl J Med 2015;373:48-59.