CSF1R and Langerhans cell histiocytosis: The remaining cases of LCH that do not bear the BRAFV600E mutation are often characterized by other mutations in the BRAF gene, mutations in ARAF, other activating mutations in the MAPK pathway downstream of BRAF (Tables 2, 3), and other activating mutations (i.e. CSF1R (17), ERBB3 (18)).