Researchers in Poland have identified several risk factors for the development of BK virus (BKV) hemorrhagic cystitis in children undergoing hematopoietic cell transplantation (HCT). Based on the factors identified, they concluded that “Excessive immune reaction connected with GVHD [graft-vs-host disease] and immunosuppressive drugs might play a pivotal role in the development of BKV hemorrhagic cystitis.”

According to the study, the results of which were published in the Annals of Hematology, “[Hemorrhagic cystitis] remains frequent and troublesome particularly in the clinically severe stage, often causing prolonged hospitalization but rarely contributed to death among children after HCT.”

This study was designed to determine the incidence and clinical course of BKV in children undergoing transplantation. The study included 133 patients who had been tested for BKV colonization and infection. BKV hemorrhagic cystitis occurred in 36 (27%) of the patients. Of the study population, patients had acute lymphoblastic leukemia (ALL; 57 patients), acute myeloblastic leukemia (AML; 11 patients), myelodysplastic syndromes (MDS; 10 patients), severe anaplastic anemia (SAA; 19 patients), primary immunodeficiencies (PID; 12 patients), and other diseases.

Continue Reading

Using univariate analysis, several factors were associated with the occurrence of hemorrhagic cystitis, including age older than 5 years, peripheral blood transplantation, matched unrelated donor transplantation, busulfan-cyclophosphamide-melphalan conditioning regimen, and AML. Additionally, the researchers noted that acute GVHD and gut GVHD were significantly associated with BKV hemorrhagic cystitis.

In the multivariate analysis, increased incidence of hemorrhagic cystitis was associated with AML, age older than 5 years, matched unrelated donor transplants, and children with GVHD.

In all, 13 patients died, including 10 with BKV hemorrhagic cystitis; however, the researchers noted that none of the deaths were attributed to BKV infection.


Salamonowicz-Bodzioch M, Frączkiewicz J, Czyżewski K, et al. Prospective analysis of BKV hemorrhagic cystits in children and adolescents undergoing hematopoietic cell transplantation. Ann Hematol. Published online March 4, 2021. doi:10.1007/s00277-021-04454-7