Multisystem Inflammatory Syndrome in a Young Adult Following COVID-19 Infection: A Case Report.

Multisystem inflammatory syndrome (MIS) after a primary infection with coronavirus disease 2019 (COVID-19) was first recognized in 2020 and presents with similar symptoms as Kawasaki disease, toxic shock syndrome, and macrophage activation syndrome/secondary hemophagocytic lymphohistiocytosis. In children, it is called multisystem inflammatory syndrome in children (MIS-C); in adults, it is termed multisystem inflammatory syndrome in adults (MIS-A). This case offers a unique presentation of MIS in a 20-year-old young adult, who turned 21 years old one week after his presentation. He fits the criteria for MIS-C and MIS-A according to the Centers for Disease Control and World Health Organization, respectively. Initial symptoms in the emergency department included headache, neck stiffness, and fever with diffuse rash. Other symptoms consistent with MIS-C/A developed rapidly later during the course of the disease.