Warm autoimmune hemolytic anemia and hemophagocytic lymphohistiocytosis/macrophage activation syndrome occurring after COVID19 infection and administration of Casirivimab + Imdevimab (COVID19 monoclonal antibody).

Warm Autoimmune Hemolytic Anemia (WAHA) is the most common form of autoimmune hemolysis and there is a growing body of evidence of an association between SARS-CoV-2 infection, WAHA and a hyperinflammatory state, including hemophagocytic lymphohistiocytosis/macrophage activation syndrome. However, there is no literature to date of WAHA or hyperinflammatory state following administration of anti-SARS-CoV-2 monoclonal antibody treatment. This report documents a case of a patient with history of WAHA who developed brisk hemolysis and a hyperinflammatory state consistent with hemophagocytic lymphohistiocytosis/macrophage activation syndrome after COVID-19 infection and treatment with an anti-SARS-CoV-2 monoclonal antibody. He was successfully treated with multimodal treatment involving steroids, intravenous immunoglobulins, rituximab, anakinra, and vincristine with resolution of the hemolysis.