Abstract
<title>Abstract</title> <p>Background Myelodysplastic syndrome (MDS) after kidney transplantation is rare, and its association with coronavirus disease 2019 (COVID-19) is unclear. Case report A 57-year-old man was treated with maintenance hemodialysis for end-stage kidney disease presumed to have been caused by chronic glomerulonephritis diagnosed 10 years earlier. After 1 year, he received an ABO-compatible living-donor kidney transplant from his sister. Renal graft function remained stable thereafter, with serum creatinine levels ranging from 1.49 to 1.62 mg/dL. Two years before presentation, he developed COVID-19, which resolved after administration of molnupiravir. However, following the COVID-19 infection, nucleated red blood cells and immature myeloid cells were persistently observed in his peripheral blood. Laboratory analyses showed hemoglobin 16.3 g/dL, white blood cell count 5,700/µL, neutrophil count 2,896/µL and platelet count 117,000/µL. Bone marrow aspiration revealed 1.4% myeloblasts, dysplastic erythroid cells with nuclear atypia, and megakaryocytes with poor platelet production and release, leading to a diagnosis of MDS. Cytogenetic analysis revealed trisomy 8, and Wilms' tumor 1 messenger RNA (WT1 mRNA) expression was elevated to 690 copies/µgRNA, suggesting a risk of leukemic transformation. Although hematopoietic stem cell transplantation was considered because of his age, no suitable related donor was available, as the kidney donor sister had developed rheumatoid arthritis. Registration with the bone marrow donor program is currently under consideration. Conclusion We experienced a case of MDS diagnosed after COVID-19 in a kidney transplant recipient. Persistent appearance of immature blood cells after COVID-19 infection may warrant careful hematological evaluation in immunocompromised patients, including kidney transplant recipients.</p>