Prognostic factors of Erdheim-Chester disease: a nationwide survey in Japan

Erdheim-Chester disease is a rare histiocytosis with insufficient clinical data. To clarify the clinical features and prognostic factors of Erdheim-Chester disease, we conducted a nationwide survey to collect the detailed data of 44 patients with Erdheim-Chester disease in Japan. The median age of onset of the participants was 51 (range: 23-76) years, and the median number of involved organs per patient was 4 (range: 1-11). The existence of central nervous system disease was correlated with older age (P=0.033), the presence of cardiovascular lesions (P=0.015), and an increased number of involved organs (P=0.0042). The median survival from the onset was 10.4 years, and >3.0 mg/dL C-reactive protein level at onset was associated with worse outcome (median survival, 14.6 vs. 7.4 years; P=0.0016). In a multivariate analysis, age >60 years (hazard ratio, 25.9; 95% confidence interval, 2.82-237; P=0.0040) and the presence of digestive organ involvement (hazard ratio, 4.74; 95% confidence interval, 1.05-21.4; P=0.043) were correlated with worse survival. Fourteen patients had available histological samples of Erdheim- Chester disease lesions. BRAFV600E mutation was detected in 11 patients (78%) by Sanger sequencing. A correlation between BRAF mutation status and clinical factors was not observed. Our study revealed that age and digestive organ involvement influence the outcome of Erdheim-Chester disease patients, and an inflammatory marker, such as C-reactive protein, might reflect the activity of this inflammatory myeloid neoplasm.