RESUMEN
Background Literature on acute generalized exanthematous pustulosis (AGEP) is restricted to case reports, with only one prior series study. More importantly, a detailed histologic comparison to pustular psoriasis has not been done. Objective To identify discriminatory characteristics, we compared the histologic features of 45 cases of AGEP and 19 cases of pustular psoriasis. Methods Demographic, historical, clinical, and histologic features of AGEP and pustular psoriasis were compared using specimens from 5 tertiary medical centers. Results The age of patients with AGEP ranged from 12 to 91 years (mean, 53 years) with a nearly equal M:F ratio. All 45 patients presented with a generalized erythematous, pustular eruption (mean duration of pustules, 12 days) and fever (present in 25/31 patients). Recent drug ingestion was documented in 36/38 (95%) patients. Of the 5 pediatric cases, two had prior upper respiratory tract infection, but were without a history of recent drug ingestion. No patient with AGEP had a history of psoriasis. AGEP was distinguished from pustular psoriasis based upon the following histologic features: necrotic keratinocytes, papillary dermal edema, presence of eosinophils within the dermis, and absence of parakeratosis with neutrophils (p <0.05). Conclusion While the precise etiology of AGEP remains unknown, our findings confirm that most AGEP cases in adults are drug-related. Certain histologic features appear to reliably discriminate AGEP from pustular psoriasis, and awareness of them may increase diagnostic accuracy.