Clinical characteristics and outcome of pediatric patients diagnosed with Langerhans cell histiocytosis in pediatric hematology and oncology centers in Poland

Langerhans cell histiocytosis (LCH) affects 1-2 in 1,000,000 people. The disease is not associated with increased risk of treatment failure (especially among older children), but appropriate procedures implemented in advance can eliminate complications which might appear and significantly worsen the patients' quality of life. Thus, we sought to evaluate the clinical features, management, and outcome of children with LCH treated in Polish pediatric hematology-oncology centers. One hundred eighty two patients with LCH were treated according to the Histiocytic Society Guidelines between 2010 and 2017. The participating centers were requested to provide the following data: demographic, clinical, as well as local or systemic treatment data and patients' outcome. Overall survival (OS) and event free survival (EFS) were estimated by Kaplan-Meier methods and compared using the log-rank test. Sixty nine percent of children were classified as single system (SS). The patients with SS disease were significantly older as compared to the children with multisystem disease (MS), 6 vs. 2.3 years respectively (p 0.003). Bones were involved in 76% of patients. Systemic treatment was applied to 47% of children with SS disease and 98% with MS disease. Fourteen patients relapsed while two children died. OS and EFS in entire group were 0.99 and 0.91 respectively (with median follow-up 4.3 years). The treatment of LCH in Polish centers was effective, however, new approaches, including mutation analyses and good inter-center cooperation, are needed to identify patients who might require modification or intensification of treatment.