Langerhans cell histiocytosis (LCH) is a hybrid disease with both neoplastic and inflammatory characteristics with clonal proliferation of bone marrow-derived CD1a, CD207+ dendric cells, and activation of mitrogen-activated protein kinase (MAPK)/extracellular signal-regulated kinases (ERK) signaling. This evidence concerns the gene CD207 and Langerhans cell histiocytosis.