Histiocytosis X has typically been thought of as a cancer-like condition. More recently researchers have begun to suspect that it is actually an autoimmune phenomenon, in which immune cells mistakenly attack the body, rather than fight infections. Extra immune cells may form tumors, which can affect various parts of the body including the bones, skull, and other areas.
Some forms of the disorder are genetic.
Histiocytosis X is thought to affect roughly 1 in 200,000 people each year. It is most often seen in children ages 1 to 15. The rate peaks among children ages 5 to10.
Pulmonary histiocytosis X is a specific type of this disorder that involves swelling of the small airways (bronchioles) and small blood vessels in the lungs. It is most common in adults. The inflammation leads to lung stiffening and damage. The cause is unknown. It most often affects those ages 30 to 40, usually cigarette smokers.
Histiocytosis X often affects the whole body. A disease that affects the whole body is called a systemic disorder.
Symptoms can vary between children and adults, although there can be some overlap. Tumors in weight-bearing bones, such as the legs or spine, may cause the bones to fracture without apparent reason.
Symptoms in children may include:
Bone pain (possibly)
Ear drainage that continues long-term
Eyes that appear to stick out (protrude) more and more
Histiocytosis X affects many organs and can lead to death.
About half of those with pulmonary histiocytosis see improvement, while others eventually have permanent loss of lung function.
In very young patients, the outlook depends on the specific histiocytosis and severity of the disease. Some children can live a normal life with minimal disease involvement, while others may have a poor outcome. Young children, especially infants, are more likely to have body-wide symptoms that lead to death.
Lipton JM, Arceci RJ. Histiocytic Disorders. In: Hoffman R, Benz EJ, Shattil SS, et al, eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 52.
Todd Gersten, M.D., Hematology/Oncology, Palm Beach Cancer Institute, West Palm Beach, FL. Review provided by VeriMed Healthcare Network.Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.