Rash in adult-onset Still disease

In 60 to 90% of people with adult-onset Still disease, a typical evanescent, salmon-pink, nonpruritic, flat rash appears with the fever on the proximal limbs and trunk. It can also be associated with a persistent erythematous maculopapular rash that may last weeks. Both types of rash are correlated with disease activity and increase the likelihood that the diagnosis is adult-onset Still disease.

If a person has a persistent urticarial rash, rather than the typical evanescent rash, they are at higher risk of haematological complicationsTomaras, 2021, including macrophage activation syndrome (MAS) (also known as haemophagocytic lymphohistiocytosis [HLH]).