Nationwide Study of Factors Impacting Survival Outcome and Consequences in Children with Reactivation/Refractory Langerhans Cell Histiocytosis.

Background: Disease reactivation/refractory remains a major challenge in managing Langerhans cell histiocytosis (LCH). Outcomes and late sequelae should be explored.
Methods: A multi-institutional retrospective study was conducted to describe clinical characteristics, predictive factors, outcomes and late sequelae of pediatric reactivation/refractory LCH in Thailand.
Results: In all, 47 patients were studied, 25 (53.2%) patients had disease reactivation and 22 (46.8%) patients had refractory LCH. The median reactivation and refractory time were 1.59 and 0.33 years from diagnosis, respectively (p <0.001). The most common site of reactivation/refractory was the bone (n = 26, 55%), and 20 (42.6%) patients developed late sequelae. The 5-year overall survival (OS) was 76.1%. Patients with reactivation and refractory LCH performed similarly in 5-year OS (88% vs. 63%, p = 0.055). Prognostic factors associated with mortality were liver, spleen, hematopoietic system and lung reactivation (p <0.05). Lung reactivation was the only independent risk factor associated with the survival outcome (p = 0.002).
Conclusions: The outcomes of pediatric patients between reactivation and refractory LCH in Thailand were similarly desirable and mortality was minimal although late sequelae may evolve. Pulmonary reactivation/refractory was an independent risk factor associated with survival.