Snapshot A 25-year-old woman, on oral contraceptives, comes to the dermatologist’s office complaining of a rash on her hands, forearms, and face. On exam, her arms and dorsal hands are covered with oozing erosions and ulcers. Alongside these ulcers are patches of hyperpigmented skin. On questioning, we find that her mother has had similar episodes. Introduction Blistering cutaneous photosensitivity caused by hepatotoxic triggers Autosomal dominant or sporadic defect in heme synthesis login to view 2 more bullets Recurrent flares triggered by hepatotoxins that upregulate heme/P450 synthesis login to view 4 more bullets Associated conditions login to view 5 more bullets Epidemiology Most common form of porphyria Middle-aged men and women Younger women on oral contraceptives Presentation Skin findings login to view 6 more bullets Non-skin findings login to view 2 more bullets Evaluation Diagnosis by skin biopsy login to view 4 more bullets Or diagnosis by urine login to view 3 more bullets To monitor login to view 1 more bullet Differential Diagnosis Pseudoporphyria (from NSAIDs) Porphyria variegata Acute intermittent porphyria Erythropoietic protoporphyria login to view 4 more bullets Treatment Avoid exposures (alcohol, estrogen, primidone, other hepatotoxins) Sunscreen use Iron removal by phlebotomy – first line login to view 2 more bullets Hydroxychloroquine login to view 1 more bullet Prevention & Complications Prevention login to view 1 more bullet Prognosis Complete clinical clearing in between 2 months and 2 years after stopping triggers exposures