Pneumocystis jirovecii Infection in children with solid tumors: Incidence and clinical characteristics in a retrospective cohort (2010-2023).

Introduction. Pneumocystis jirovecii pneumonia (PJP) is a life-threatening infection that affects patients with impaired immunity (primarily cellular immunity). Given that few studies have evaluated the incidence of PJP in pediatric patients with solid tumors, the objective of this study was to estimate the incidence of PJP among pediatric patients with solid tumors treated at a general hospital. Population and methods. A retrospective cohort study of 251 patients under 18 years of age with a confirmed diagnosis of solid organ cancer treated at a general hospital. Clinical, oncological, and infectious disease characteristics were evaluated. The cumulative incidence and incidence density of PJP were calculated, along with their respective 95% confidence intervals. Results. The cumulative incidence of PJP was 2.4% (95%CI 0.9-5.1), with an incidence rate of 8.4 cases per 1000 person-years (95%CI 3.8-18.6), and a median time from cancer diagnosis to infection of 2.7 months (IQR 2-4.5)-most patients presented with moderate symptoms. Conclusion. PJP can occur in children and adolescents with solid tumors, although its incidence is low and the prognosis is generally favorable in this cohort. These findings provide important insights into the risk profile in this population and highlight the need for further studies to determine its clinical impact and the role of prophylaxis.