Histiocytosis refers to a group of disorders in which there is an abnormal amount of scavenger cells, called histiocytes, in the blood.
There are histiocytosis diseases that affect adults and those that affect children. In adults, the lungs are affected. There is inflammation of the small airways and small blood vessels in the lungs. It is often linked with cigarette smoking. In children the bones are affected. In many cases the skull is involved. However, any other single site or multiple sites can be affected.
Although the cause of histiocytosis is unknown, it is much more likely to occur in a person who smokes cigarettes.