Subtypes and Prognostic Factors in Erdheim-Chester Disease

The study of BRAF mosaicism will be conducted on biopsy samples from patients with ECD and other neoplasms co-occurring with the BRAFV600E mutation. The samples will be labeled with anti-Pu.1-Alexa Fluor 647 antibody (which binds to macrophages), then DNA will be extracted using FACS method and amplified using MDA (Qiagen Repli-G Single-Cell kit). Quality control will be performed using Quant-it (ThermoScientific) and Agilent 4200 TapeStation. Eligible samples will undergo digital droplet PCR (ddPCR) and sequencing. ddPCR probes for wild-type and mutant alleles will be used. Sequencing will be performed using Illumina HiSeq 2500 system