Pseudoporphyria induced by propionic acid derivatives.

BACKGROUND: Pseudoporphyria is a photosensitive bullous skin disease that is distinguished from porphyria cutanea tarda (PCT) by its normal porphyrin profile. Drugs are a major cause of this disease, and the list of culprits is continually expanding. Nonsteroidal antiinflammatory agents (NSAIDs), especially naproxen and other propionic acid derivatives, appear to be the most common offenders.

OBJECTIVE: The study was carried out to increase awareness about the etiology and characteristic features of pseudoporphyria.

METHODS: We report two cases of pseudoporphyria caused by naproxen and oxaprozin. We review the current English language literature on this entity and discuss its clinical features, histology, ultrastructure, etiology, and pathophysiology.

RESULTS: A 44-year-old man taking naproxen for chronic low back pain and a 20-year-old woman on oxaprozin for rheumatoid arthritis presented with tense bullae and cutaneous fragility on the face and the back of the hands. In both, skin biopsy showed a cell-poor subepidermal vesicle with festooning of the dermal papillae. Direct immunofluorescence revealed staining at the dermal-epidermal junction and around blood vessels with IgG in the first case and with IgG, IgA, and fibrin in the second case. Urine collections and serum samples yielded normal levels of uro- and coproporphyrins.

CONCLUSIONS: Most cases of pseudoporphyria are drug-induced. Naproxen, the most common offender, has been associated with a dimorphic clinical pattern: a PCT-like presentation and one simulating erythropoietic protoporphyria in the pediatric population. Other NSAIDs of the propionic acid family can also cause pseudoporphyria.