Rash associated with adult onset Stills disease
Although the rash is said to occur in the vast majority of patients with AOSD, it is often unappreciated unless specifically sought. The characteristic appearance is that of evanescent, salmon-colored, macular or maculopapular lesions that are nonpruritic. The rash is usually seen on the trunk, arms, legs, or areas of mechanical irritation such as tight clothing (beltline). Often, it is only seen when the patient is febrile. The rash can sometimes be elicited with heat, such as that produced by applying a hot towel or taking a hot bath or shower. Koebner phenomenon (i.e., the rash can be induced by rubbing the skin) is reported in approximately 40% of patients. Atypical skin rashes and urticarial lesions have also been reported in up to 14% patients. Skin biopsies and immunofluorescent studies are nondiagnostic, showing dermal edema and a perivascular mononuclear cell infiltrate. Purpuric lesions with thrombocytopenia should suggest an associated hematologic complication that could be life-threatening such as MAS/ reactive hemophagocytic lymphohistiocytosis (MAS/RHL), DIC, or TTP.
