Fig. 1

Clinical information of Case 1 from hematopoietic cell transplantation (HCT) to death. a The clinical course from HCT to admission. b The clinical course during the last hospitalization. c-e Images of the non-enhanced chest CT scans. c Inflammation of the posterior segment of the upper lobe and the lateral segment of the middle lobe, with patchy hyperintensity and vague margin. d Diffuse systemic inflammation in both lungs, with increased, thickened, and disorganized texture, multiple diffuse plaques, and patchy, nodular hyperintensities. e Diffuse systemic inflammation in both lungs that was significantly more progressive than in d. Lesions were located along the peribronchial sheath, showing fused patchy consolidation and ground-glass opacity, and high density in some nodules. f-i The bone marrow smear results. f, g Suppressed bone marrow proliferation, including for the granulocyte, erythroid, and macrophage lineages, with variable sizes of mature erythrocytes. Single platelets were rarely seen, indicating immune-mediated bone marrow failure. h, i Active bone marrow proliferation, with a granulocyte to erythrocyte ratio of 16.8:1. The monocyte proportion increased with no abnormalities in morphology, and platelets were relatively easily seen. j, k Pathology findings of BKPyVAN. j Hematoxylin and eosin (HE) staining. k Immunohistochemistry (IHC) against SV40-T. BALF, bronchoalveolar lavage fluid; BKPyV, BK Polyomavirus; CMV, cytomegalovirus; CRP, c reactive protein; CSA, cyclosporine A; EBV, Epstein–Barr virus; GVHD, graft versus host disease; HGB, hemoglobin; IVIG, intra-venous immunoglobulin; MMF, mycophenolate mofetil; mNGS, metagenomic next-generation sequencing; NEU, neutrophil count; PCT, procalcitonin; PLT, platelet count; RAPA, rapamycin; SCR, serum creatinine; WBC, white blood cell counts