BRAF V600E mutations have not been reported in RDD thus far, although KRAS and MAP2K1 mutations have been identified in common mitogen-activated protein kinase/extracellular signal-related kinase pathways (MAPK/ERK) in a small subset of RDD patients [12]. This supports previous theories of clonal etiology in a subset of RDD patients, which could be promising for the use of targeted therapies. The gene discussed is MAP2K1; the disease is sinus histiocytosis with massive lymphadenopathy.