Still disease with persistent atypical dermatomyositis-like skin eruption: two cases associated with macrophage activation syndrome.

The typical rash of Still disease is an asymptomatic, salmon-coloured, macular, or maculopapular eruption that appears along with the fever spikes and fades when the body temperature drops. Although not included in the diagnostic criteria, there are other frequent, persistent, pruritic and polymorphic skin manifestations of Still disease that have distinctive clinical features and specific histological findings. Among these atypical persistent pruritic eruptions (PPEs), periorbital erythema and linear flagellate papules and plaques can resemble the cutaneous manifestations of dermatomyositis (DM). The presence of these lesions in adult-onset Still disease has been associated with worse prognosis and higher mortality rates, perhaps due to the development of a secondary macrophage activation syndrome (MAS). We report two cases of Still disease with persistent atypical DM-like eruption, one in a paediatric patient (a very underreported finding) and the other in an adult. Both cases developed a secondary MAS.