Polyoma BK virus (BKV) infection/reactivation is an important underlying condition that provokes hemorrhagic cystitis (HC) in hematopoietic stem cell transplantation (HSCT) recipients. However, BKV associated infections can rarely occur in acute leukemia patients without receiving HSCT. Here we present 12 pediatric acute leukemia patients with BKV infection during leukemia treatment.

Between September 2019 and July 2023, in Ankara Bilkent City Hospital, BKV by quantitative polymerase chain reaction (PCR) detected in the urine of 12 pediatric leukemia patients who had not got HSCT but receiving intensive chemotherapy. The clinical characteristics of these infections were retrospectively evaluated.

Ten of the 12 patients had acute lymphoblastic leukemia (ALL). Seven of the 10 ALL cases were T cell ALL. Ten of the patients were male and 10 of the patients’ age were 10 years and older. Eleven patients experienced HC and one patient had epididymitis. The copy number of BKV varied between 470 to 1.3 trillion /mL. Seven patients had got treatment ranging from hydration, ciprofloxacin to bladder irrigation. Except a refractory T cell ALL patient, all of the patients had clinical improvement.

Although it is a major complication of HSCT and solid organ transplantation, BK virus infection can also occur in pediatric acute leukemia patients during treatment. As in HSCT recipients, male gender and older age seems as risk factors in leukemia patients. Due to complete loss of virus specific T lymphocytes, T cell ALL patients may be more prone BK virus activation.