MAP2K1 and sinus histiocytosis with massive lymphadenopathy: To date, approximately 33–50% of cases were detected with the genomic mutation involving KRAS, NRAS, serine/threonine-protein kinase A-Raf (ARAF), and MAP2K1 in RDD [21,28,29,30,31,32,33], and only two cases with BRAF mutation were reported [34,35].