Abstract

Pseudoporphyria mimics the presentation of porphyria cutaneous tarda (PCT), but patients have no identifiable abnormalities in porphyrin metabolism. Pseudoporphryia is a rare condition with unknown pathogenesis, but it has been associated with medications, chronic renal failure and hemodialysis, and ultraviolet radiation, including tanning bed use. Since pseudoporphyria is identical to PCT both in clinical and histopathologic presentation, diagnosis can only be made after finding normal porphyrin levels.  A 37-year-old Black woman with end-stage renal disease necessitating hemodialysis, type 2 diabetes mellitus, and obesity was admitted to the hospital with bullous eruption involving her extremities. Dermatologic examination showed tense blisters without inflammation on the right dorsal foot and right forearm; initial differential diagnosis included pseudoporphyria induced by hemodialysis, bullosis diabeticorum, immunobullous disease, porphyria, or multifocal soft tissue infection with bullae. A punch biopsy revealed a subepidermal blister with moderate mixed inflammatory infiltrate, festooning of the dermis into the blister cavity, and prominent perivascular hyalinization. Direct immunofluorescence examination was also performed, showing smooth deposits of immunoglobulins and C3 within superficial vessel walls. These findings were compatible with both porphyria and pseudoporphyria. Total plasma porphyrin levels were normal, confirming the clinical impression of pseudoporphyria due to hemodialysis. This case illustrates a rare complication of hemodialysis and a major cause of pseudoporphyria. While there are no major complications, scarring may occur. Recognition and treatment initiation is important to reduce patient discomfort and distress.