Posterior Reversible Encephalopathy Syndrome in Children with Malignancies or After Hematopoietic Cell Transplantation: A Polish Nationwide Study.

Background/Objectives: The objective of this study was to analyze the clinical and laboratory features, management, outcomes, and complications of PRES in children with malignancies or following hematopoietic cell transplantation (HCT). Methods: This was a multicenter retrospective analysis of PRES episodes diagnosed between 2014 and 2022 in Polish pediatric hematology and oncology (PHO) centers and HCT units. The study included 438 patients treated for malignancy or post-HCT: 120 with PRES (study group) and 318 without PRES (control group). Results: PRES was diagnosed in children aged 1.7-16.5 years (median = 7.7 years). The most common underlying diagnosis was ALL (76.7%; n = 92). Symptoms of PRES included disturbances of consciousness (84.2%), seizures (80.0%), hypertension (74.2%), apathy (64.2%), abdominal pain (45.0%), visual disturbances (28.3%), and headaches (26.7%). Electrolyte abnormalities were observed in 75.0% of children, most commonly hyponatremia (49.2%) and hypokalemia (37.5%). Children with PRES were more likely to require admission to the intensive care unit (ICU) than controls (50.0% vs. 29.6%, p < 0.001). The most frequent long-term complications of PRES were hypertension (22.5%) and epilepsy (20.8%). Among PHO patients, those with PRES had significantly lower DFS (76.7% vs. 93.7%, p < 0.001) and OS (79.2% vs. 93.4%, p < 0.001). In the HCT group, PRES was also associated with lower DFS (40.0% vs. 83.3%, p = 0.012) and OS (40.0% vs. 77.8%, p = 0.047). Conclusions: PRES is a significant complication of oncological and transplant treatment in children. Its occurrence was associated with worse overall and disease-free survival. We proposed a predictive index for PRES, diagnostic criteria, and a revised name for this syndrome.