The abnormal cells in LCH are actually derived from myeloid dendritic cells that exhibit the same antigens (CD1a, S100 protein, and Langerin) and the same unique intracytoplasmic organelles (Birbeck granules) with the normal Langerhans cells found in the skin and mucosa [1]. The gene discussed is CD207; the disease is Langerhans cell histiocytosis.