[BK virus encephalitis in children with hematopoietic stem cell transplantation]

Objective: To explore the morbidity, mortality, median onset time, clinical characteristics, diagnosis, treatment, and outcome of BK virus (BKV) central nervous system infection in children with allogeneic hematopoietic stem cell transplantation (allo-HSCT) , and improve the understanding, clinical diagnosis, and treatment of the disease. Methods: Seven hundred and nine children who received haploid HSCT treatment in Peking University People's Hospital from January 1, 2015 to December 31, 2020 were reviewed. Fourteen patients were diagnosed with BKV central nervous system infection, and their clinical characteristics, treatment process, and prognosis were analyzed. Results: The incidence of BKV central nervous system infection was 1.97% (14 cases) , mostly in men (12 cases) , with a median age of 11 years old and median onset time of 55 d. Additionally, most of the cases showed disturbance of consciousness and seizures (seven cases) . Furthermore, 14 cases were treated with acyclovir and ganciclovir alone or with gamma globulin. Nine cases were cured, of which one died of viral encephalitis and four of other diseases, with a mortality rate of 35.7%. Conclusion: Individuals with central nervous system involvement by BKV infection, usually show signs and symptoms of acute encephalitis, with some cases being accompanied by meningeal involvement. Although BKV encephalitis was diagnosed and actively treated with drugs, many patients still died of multiple organ failure or other complications. Therefore, when there are neurological symptoms and hemorrhagic cystitis in patients with allo-HSCT, it is necessary to be highly vigilant against BKV central nervous system infection. This helps to make clear diagnosis and treatment quickly; thus, improving the survival rate and quality of life of patients with HSCT.