BK virus is one of the most common causes of hemorrhagic cystitis (HC) in children undergoing hematopoietic cell transplantation (HCT). Viruses can be found in urine and serum samples of immunocompromised patients. Malignant diseases, age, cell source, day of granulocyte reconstitution, conditioning regimen, or use of total body irradiation may play an important role in BKV epidemiology, development of hemorrhagic cystitis course, and outcome. The aim of this study was to evaluate the incidence, clinical course, and risk factors for BKV-HC in children undergoing HCT. A total number of 133 patients who were prospectively tested for BKV colonization/infection were enrolled into this multicenter analysis. Episodes of BKV-HC occurred in 36/133 (27%) enrolled subjects. In a univariate analysis for BKV-HC incidence, the following factors were significant: age >5 years, peripheral blood transplantation, matched unrelated donor (MUD) transplantation, busulfan-cyclophosphamide-melphalan conditioning regimen, and acute myeloblastic leukemia (AML) diagnosis. Presence of acute graft-versus-host disease (aGVHD) in liver and gut GVHD was a significant risk factor of BKV-HC. No BKV-attributed deaths were reported. In multivariate analysis, the incidence of HC was significantly higher in patients with AML, age >5 years, MUD transplants, and children with GVHD. HC is a frequent complication after HCT among children causes prolonged hospitalization but rarely contributes to death. We identified risk factors of BKV-HC development in children, with focus on aGVHD: we concluded that excessive immune reaction connected with GVHD and immunosuppression drugs might play a pivotal role in the development of BKV-HC.

Allo‐HSCT is associated with life‐threatening complications. Therefore, a considerable number of patients require admission to a PICU. We evaluated the incidence and outcome of PICU admissions after allo‐HSCT in children, along with the potential factors influencing PICU survival. A retrospective chart review of 668 children who underwent first allo‐HSCT in the Department of Pediatric Hematology/Oncology and BMT in Wrocław during years 2005‐2017, particularly focusing on patients admitted to the PICU within 1‐year post‐HSCT. Fifty‐eight (8.7%) patients required 64 admissions to the PICU. Twenty‐four (41.5%) were discharged, and 34 (58.6%) patients died. Among the discharged patients, 6‐month survival was 66.7%. Compared with survivors, death cases were more likely to have required MV (31/34; 91.2% vs. 16/24; 66.7% P = .049), received more aggressive cardiac support (17/34; 50% vs. 2/24; 8.3% P = .002), and had a lower ANC on the last day of their PICU stay (P = .004). Five patients were successfully treated with NIV and survived longer than 6 months post‐discharge. The intensity of cardiac support and ANC on the last day of PICU treatment was independent factors influencing PICU survival. Children admitted to the PICU after allo‐HSCT have a high mortality rate. Mainly those who needed a more aggressive approach and had a lower ANC on the last day of treatment had a greater risk of death. While requiring MV is associated with decreased PICU survival, early implementation of NIV might be considered.

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Hematopoietic stem cell transplantation (HSCT) is a curative therapy for an increasing number of nonmalignant indications. Its use is restricted by severe transplant-related complications, including CMV infection; despite various prophylactic and therapeutic strategies, CMV reactivation has remarkable morbidity and mortality. The analysis included 94 children with nonmalignant disorder who underwent allogeneic HSCT in the Department of Pediatric Hematology, Oncology, and Bone Marrow Transplantation in Wrocław during years 2016–2020. Twenty-seven (29%) children presented with CMV infection, including ten (10/27; 37%) with high level CMV viremia (10,000 copies/mL). Six patients experienced subsequent CMV reactivation. The first-line ganciclovir-based (GCV) treatment was insufficient in 40% (11/27) of children. Overall survival (OS) was significantly lower in children with high CMV viremia compared to those with low levels/no CMV [1yrOS High CMV = 0.80 (95% CI 0.41–0.95) vs. 1yrOS others = 0.96 (95% CI 0.89–0.99)]. Similarly, patients with resistant and recurrent infections had greater risk of death. CMV reactivation at any level relevantly prolonged the hospital stay. CMV reactivation with high viremia load and resistant/recurrent CMV infections lead to a significant decrease in OS in children with nonmalignant disorders treated with HSCT. Our data proves there is an urgent need to introduce an effective anti-CMV prophylaxis in this cohort of patients.

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