Langerhans cell histiocytosis (LCH) is a proliferative histiocytic disorder of unknown cause characterized by the accumulation of Langerhan cells in various tissues.

• 郎格罕细胞性组织细胞增生症是一种不明成因的增生性组织细胞疾病，其特徵为郎格罕细胞积聚于多个不同组织。