CASE DESCRIPTION
A 15-year-old male receiving cyclosporine for AA was admitted to the University of Tokyo Hospital due to fever. He was diagnosed with severe AA four months ago. Since a human leukocyte antigen-matched sibling donor was unavailable, he received IST with corticosteroids, rabbit antithymocyte globulin, and cyclosporine combined with eltrombopag. He was discharged and barely achieved a partial response two months after IST initiation (Fig. 1). At the time of his hospitalization, he presented with a fever (39.2˚C) and mild sore throat that was noted one day previously. His white blood cell count was 1.0 × 109/L, with absolute neutrophil and lymphocyte counts of 0.67 × 109/L and 0.18 × 109/L, respectively. The hemoglobin level was 9.8 g/dL, and the platelet count was 45 × 109/L without transfusion for more than two months. The serum IgG level was low at 503 mg/dL (reference value, 861–1747 mg/dL). Other blood examinations were unremarkable. The chest radiograph did not show any evidence of pneumonia.
On day 2 (the onset of COVID-19 was considered day 0), the patient tested positive on nasopharyngeal swab polymerase chain reaction testing for SARS-CoV-2. As a part of IST, cyclosporine was continued with trough concentrations of 150–250 ng/mL. After receiving intravenous immunoglobulin and a single dose of hydrocortisone, he became afebrile on day 2. Although the complete blood count fluctuated slightly, he did not require transfusion or granulocyte-colony stimulating factor. He was discharged on day 10 without sequelae attributed to COVID-19 for four months.