ABSTRACT
A 67-year-old Japanese man was admitted to our hospital with severe coronavirus disease 2019 (COVID-19) in March 2020. Mechanical ventilation was initiated 8 days after admission, due to severe respiratory failure. Multiple severe complications such as liver dysfunction, arrhythmia, brain infarction, and venous thromboembolism were also observed. We initially diagnosed Coombs test-positive warm autoimmune hemolytic anemia. Corticosteroids proved ineffective and anemia worsened with severe erythroid hypoplasia (0.5% erythroblasts in bone marrow), so we diagnosed pure red cell aplasia (PRCA). We also identified massive infiltration of cytotoxic T-lymphocytes expressing CD8, granzyme B, and perforin in bone marrow. Systemic cyclosporine was started, with full resolution of anemia and no need for blood transfusions after 4 weeks. We believe that this represents the first report of COVID-19-associated PRCA successfully treated using cyclosporine.