CT scan of a growth due to Langerhans cell histiocytosis in the skull near the eye, courtesy Countincr via Wikimedia Commons
Langerhans cell histiocytosis, also known as histiocytosis X, is a type of autoimmune disease related to uncontrolled production of certain types of cells of the immune system called Langerhans cells, which play a role in transporting antibodies to the skin. The production of these cells goes on unabated and the body responds with general inflammation that results in the symptoms of the disease.
Although it is an autoimmune disease, the National Cancer Society does recognize LCH as cancer, and it's treated as such. If the inflammation is localized, surgery is generally effective. Otherwise, radiation therapy and chemotherapy are indicated. Patients generally respond well to treatment although patients, where the disease is widespread, will generally have to be treated throughout their lives.
Diagnosis is usually with a biopsy, which shows the distinctive shape of the Langerhans cells.
LCH is rare and generally presents in children under the age of 10. It's even rarer in adults and is almost unheard of in the elderly.