CD1A and Langerhans cell histiocytosis: Langerhans cell histiocytosis (LCH), also known as histiocytosis X, affects mainly young children with a peak incidence between the ages of 1 and 3 y, and features granulomas consisting of macrophages, multinucleated giant cells, lymphocytes, eosinophils, and CD1a+ Langerin+ Langerhans-like cells, accumulating within various tissues such as bone, skin, lung, liver, bone marrow, lymph nodes, the gastrointestinal tract, and the central nervous system [1–6].