In addition to pathologic dendritic cells,[2] several immune cells (e.g., T cells, eosinophil, and macrophages) and many cytokines/chemokines have been reported to be involved in LCH lesions.[3] Despite the diverse clinical presentations of LCH, the histologic presentation is primarily consistent with immunohistochemical evaluations for CD1a and Langerin/CD207.[4,5]. The gene discussed is CD1A; the disease is Langerhans cell histiocytosis.