Journal Club

BK Virus in Pediatric Stem Cell Transplants: It’s Not Just in the Bladder

By Terri Stillwell, MD

BK virus (BKV) is known to cause nephropathy in renal transplant recipients and hemorrhagic cystitis in stem cell transplant recipients. However, we do not often see the reverse, i.e., hemorrhagic cystitis in renal transplants or nephropathy in stem cell transplants. A recent study in the Journal of the Pediatric Infectious Diseases Society provides a new look at risk factors and outcomes of BKV in pediatric stem cell transplant recipients.

This single-center retrospective study reviewed all pediatric allogenic hematopoietic stem cell transplants (HSCTs) over a 4-year period (January 2011 to December 2015). In total, 314 HSCT recipients were studied, from the time of transplant to 5 years post-HSCT. Outcomes assessed included presence of BKV hemorrhagic cystitis (BKV-HC) as well as markers of kidney injury.

Sixty-seven (21.3%) recipients were found to have developed BKV-HC, with a median of time-to-hematuria of 37 days post-HSCT and a majority of cases presenting within the first 4 months post-HSCT. Not surprisingly, those with BKV-HC were more likely to have an underlying malignancy (as opposed to nonmalignant underlying disease, P < .0001); have undergone myeloablative conditioning (P = .002); have severe graft-vs-host disease (P = .028); or have concomitant viremia (with cytomegalovirus and/or adenovirus, P < .0001). A somewhat new finding was that those with BKV-HC were more likely to develop stage 2 and stage 3 acute kidney injury, and were more likely to develop a need for dialysis. Additionally, those who experienced BKV-HC within the first year post-HSCT were more likely to have mild to moderate chronic kidney disease.

The identified risks factors for developing BKV-HC are likely indicators of individuals’ overall immune suppressed state and are not unexpected. However, the findings of both acute and long-term impacts on kidney function are not often described in pediatric HSCT recipients. While these findings are likely multifactorial, they are important outcomes as we try to understand the effects of BKV.

(Ruderfer et al. J Pediatric Infect Dis Soc. 2021;10(4):492–501.)