Steroid-resistant Acute Generalized Exanthematous Pustulosis Mimicking Generalized Pustular Psoriasis Successfully Treated by Methotrexate

Abstract

Acute generalized exanthematous pustulosis is a rare drug-induced eruption that is characterized by sterile non-follicular pustules arising on an often edematous diffuse erythematous background. Generalized pustular psoriasis is an acute and severe clinical form of psoriasis presenting as pustular eruption with erythematous base. Differentiating both diseases is often challenging because of their clinical and histopathological similarities. A 62-year-old woman presented with pustular eruption and fever three days after taking propyphenazone. Laboratory findings revealed leukocytosis and neutrophilia. Histopathological findings revealed a subcorneal spongiform pustule filled with neutrophils and perivascular inflammatory cell infiltration with neutrophils in the dermis. She was initially treated with systemic steroids, however, the lesions showed insignificant improvement. Treatment was then shifted to methotrexate which resulted in a dramatic clinical improvement.