Amicrobial pustulosis of the folds: A case report of a rare variant of neutrophilic dermatosis associated with systemic lupus erythematosus.

Amicrobial pustulosis of the folds (APF) is a rare neutrophilic dermatosis found in association with autoimmune diseases. We present a 49-year-old woman with a history of systemic lupus erythematosus and a recurrent pustular eruption in the cutaneous folds. Histologic examination revealed spongiform pustulosis and dermal neutrophilic infiltrate. The Gram and periodic acid-Schiff stains were negative for bacteria and fungi. A diagnosis of amicrobial pustulosis of the folds was given. While there is no standard treatment, our patient's symptoms resolved following an oral prednisone taper and have not recurred since starting colchicine. The presence of pustules and erosive plaques in skin folds in young women with autoimmune conditions should raise suspicion for APF. The combination of localized neutrophilic spongiosis with intraepidermal or subcorneal pustules in conjunction with dermal changes of a neutrophilic dermatosis is a helpful clue to the diagnosis. If the patient does not already have a diagnosis of an underlying autoimmune condition, a presentation of APF should prompt further screening consisting of a relevant review of symptoms and appropriate assessment for autoimmune antibodies, since APF may precede the diagnosis of autoimmune disorders.