The clinical spectrum and prognostic factors of Erdheim-Chester disease and mixed Langerhans cell histiocytosis and Erdheim-Chester disease.

Erdheim-Chester disease (ECD) is a rare and probably fatal multisystemic non-Langerhans cell histiocytosis (LCH). To comprehensively investigate the clinical features, genomic analysis, treatments, and prognostic factors of ECD, we retrospectively analyzed the clinical data of 75 ECD patients and 10 mixed LCH and ECD patients in our center. The median age at diagnosis was 46 years (range, 5-70). ECD patients were older at diagnosis (p = 0.006) and had more cardiac involvement (p = 0.011) as well as vascular (p = 0.031) involvement compared to mixed LCH and ECD patients. 64.8% of ECD patients and 87.5% of mixed LCH and ECD patients carried BRAF mutation. The BRAF mutation correlated with a greater number of affected organs (p = 0.030) and was associated with lung involvement (p = 0.033) as well as pleural involvement (p = 0.002). The median follow-up time was 38 months (range, 1-174). The estimated 5-year progression-free survival (PFS) and overall survival (OS) were 48.9% and 84.7%, respectively. In a multivariate analysis, right atrial pseudotumor (p = 0.013) and pancreatic involvement (p = 0.005) predicted worse OS, while pleural (p = 0.042) and central nervous system (CNS) involvement (p = 0.043) predicted worse PFS. Our study described the clinical spectrum of ECD and mixed LCH and ECD, while also revealed the prognostic value of right atrial pseudotumor and pancreatic, pleural, and CNS involvement for worse survival.