Macrophage activation syndrome in MDA5 antibody-positive dermatomyositis and COVID-19 infection

BACKGROUND: Macrophage activation syndrome (MAS) is a rare multiorgan system disorder that may present as a fatal complication of underlying rheumatological disease, including dermatomyositis. CASE PRESENTATION: Here, we report the case of a 65-year-old Caucasian female with a history of psoriasis and a recent diagnosis of Coronavirus disease 2019 (COVID-19) who presented with progressive generalized weakness, joint pains, an erythematous rash, shortness of breath, and weight loss. She was ultimately diagnosed with biopsy-confirmed melanoma differentiation-associated protein 5 (MDA5)-positive dermatomyositis complicated by MAS, requiring intravenous immunoglobulin and high-dose methylprednisolone. CONCLUSIONS: This report serves as a clinical reminder of the rare, yet clinically relevant association between MDA5-positive dermatomyositis and MAS, as well as highlights the potential contribution of other immune system activating diseases, such as COVID-19, associated with a cytokine storm and hyperinflammatory state.