Histiocytosis X or LCH is a family of related conditions, which are characterized by a distinct inflammatory and proliferative process but which differ from each other regarding what parts of the body are involved.
Histiocytosis X is a generic term that refers to an increase in the number of histiocytes, a type of white blood cell that acts as a scavenger to remove foreign material from the blood and tissues.
Research that demonstrated Langerhans cell involvement as well as histiocytes led to a proposal that the term Langerhans cell histiocytosis (LCH) be used in place of histiocytosis X.
The symptoms of histiocytosis are caused by substances called cytokines and prostaglandins, which are normally produced by histiocytes and act as messengers between cells.
Histiocytosis X is a rare disorder affecting only approximately one in 200,000 children or adults each year.