Pediatric hemophagocytic lymphohistiocytosis in a tropical country: Results of a multicenter study in Thailand

Background Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening condition caused by genetic mutation or various triggers disturbing the immune system. Methods A multicenter retrospective study of pediatric patients with HLH receiving a diagnosis between January 2005 and December 2019 from three pediatric oncology centers was conducted to explore the clinical characteristics and determine prognostic factors associated with outcomes among Thai children. Results In all, 78 patients with HLH with a median age at diagnosis of 3.17 (range, .08-17.83) years were enrolled. The male to female ratio was 1.2:1. The most common type of HLH was infection-associated hemophagocytic syndrome (IAHS) (n = 59, 75%) of which Epstein-Barr virus was the most common pathogen. Thrombocytopenia, hyperbilirubinemia, and treatment response at weeks 2 and 8 after initiating treatment were associated with mortality. Platelet count <50,000 cells/mm(3) was the only independent prognostic factor to define survival outcome (p-value .035). Two-year overall survival rate was 71.3% (95% confidence interval, 59.2%-80.3%). Survival rates between IAHS, malignant associated HLH, macrophage activation syndrome, and unspecific HLH did not significantly differ (p-value .571). Conclusion IAHS was the most common cause among pediatric HLH in Thailand. The outcomes of Thai children with HLH were comparable to those of developed countries. Platelet count <50,000 cells/mm(3) was the only independent prognostic factor to define survival outcome.