B-RAF is a member of the RAF-family of kinases which plays an important role in the RAS-RAF-MEK-ERK mitotic signaling pathway. Mutations of B-RAF have been described in up to 100% of Hairy cell leukemia, 40-70% of Langerhans cell histiocytosis, approximately 50% of Erdheim-Chester disease, approximately 5% of diffuse large B cell lymphoma and plasma cell neoplasms and less than 5% of chronic lymphocytic leukemia. While some reports have found that 10-20% of cases of acute leukemias (ALL or AML) may have BRAF mutations, other reports have described no BRAF in those diseases or in myeloid diseases such as MDS or CML. The hotspot for mutations in BRAF is at codon Val600 and these are activating mutations. The most common activating mutation is p.Val600Glu(V600E). Various B-Raf inhibitors(Vemurafenib, Dabrafenib) have been FDA approved for therapy for some tumor types in certain clinical settings.