Pseudoporphyria cutanea tarda Induced by Furosemide in a Patient Undergoing Peritoneal Dialysis

We report on a 32-year-old female patient undergoing peritoneal dialysis for diabetic nephropathy who developed blisters and cutaneous fragility on the dorsa of the hands. Histopathology of an early lesion showed a subepidermal cleft under a regular epidermis with single necrotic keratinocytes and normal dermal structures. In an advanced lesion, a subepidermal bulla and caterpillar bodies were found in the epidermis. Dermal vessel walls were normal and surrounded by a discrete lymphocytic infiltrate. Direct immunofluorescence revealed perivascular deposits of C3. Uroporphyrin and coproporphyrin levels of serum, urine and dialysate were repeatedly normal, confirming pseudoporphyria. The patient took furosemide (500 mg daily). Replacement of furosemide by ethacrynic acid led to spontaneous healing of the blisters. The patient was free of further lesions at the 1-year follow-up.