An Atypical Skin Presentation of Adult‐Onset Still's Disease With Histological Description: A Case Report

ABSTRACT Adult‐onset Still's disease (AOSD) is an auto inflammatory disorder with a variable clinical presentation, and without a pathognomonic diagnostic test, characterized by high spiking fever, arthralgia/arthritis, a suggestive skin rash, elevated white blood cell count 10 G/L (> 80% neutrophils), elevated ferritin, with glycosylated ferritin < 20% and high IL‐18. Cutaneous manifestations are very frequent and the commonest description is an evanescent salmon‐pink rash, although many atypical skin presentations have been described in literature. We present the case of an atypical cutaneous manifestation of clinically typical AOSD in a 30‐year‐old man presenting with a slightly pruritic maculopapular and urticarial erythematous rash on the face and limbs, with purpuric features on the lower limbs, which gradually spread to the whole body, associated with overlying nonfollicular pustules. The patient also presented with high spiking fever, odynophagia, diffuse arthralgia, and generalized asthenia. The histological analysis of a skin biopsy showed a few subcorneal collections of neutrophils, a slight epidermal spongiosis, many suprabasal necrotic keratinocytes, and a moderate mixed inflammatory infiltrate in the superficial dermis. Following various investigations ruling out any other diagnosis, we have diagnosed Still's disease, for which the patient has been prescribed corticosteroids, with good initial results.