BRAF and Langerhans cell histiocytosis: In some of the histiocytic neoplasms, especially in Langerhans cell histiocytosis and Erdheim‐Chester disease, neoplastic cells often display mutations in genes triggering the MAPK pathway, including mutations in BRAF (most prevalent: V600E), ARAF, MAP2K1, NRAS or KRAS [27].