Post-Streptococcal Neutrophilic Pustular Dermatosis: Expanding the Histopathological Paradigm of Reactive Neutrophilic Dermatoses.

Post-streptococcal pustulosis was first described in 1974 by Tan et al., and was only clearly distinguished from acute generalized exanthematous pustulosis in 1995. It is a rare neutrophilic dermatosis which usually arises following group A streptococcal infections, and is self-limited in time, typically resolving with 1 month. Clinical presentation includes a roughly symmetrical sterile pustular eruption arising in normal skin, most often affecting acral areas, like palms, soles, and legs. Up to this date, only 26 cases have been documented worldwide, making it a rare phenomenon. Differential diagnosis with other conditions, namely AGEP and pustular psoriasis (PP), might prove challenging. We present a case of a 52-year-old woman who came to our clinic with a 2-day pustular eruption of the acral areas that arose after a streptococcal pharyngitis. A skin biopsy was performed and revealed a dense neutrophilic infiltrate around the superficial dermis with microabscess formation in the dermal papillae, which was consistent with the diagnosis of post-streptococcal pustulosis. The patient was treated with topical steroids and the lesions resolved within 2 weeks. In this paper, we highlight this rare entity and provide some clinical clues that may help distinguish this disease from AGEP and PP.