These mutations, particularly the BRAF V600E mutation affecting dendritic cell precursors or monocytes, drive the pathological activation of the RAS-RAF-MEK-ERK mitogen-activated protein kinase signaling pathways in diseases such as LCH, ECD, JXG, and RDD (Fig. 6). This evidence concerns the gene BRAF and sinus histiocytosis with massive lymphadenopathy.