Langerhan's Cell Histiocytosis (LCH) is a rare blood disease that is caused by an excess of white blood cells called histiocytes. A histiocyte is a form of white blood cell. Its job is to help destroy certain foreign materials and fight infection. For unknown reasons, patients with this disease have too many histiocytes (Langerhans cells). These cells accumulate in different organs and can result in a variety of symptoms. The histiocytes cluster together and can attack the skin, bones, lung, liver, spleen, gums, ears, eyes, and/or the central nervous system. The disease can range from limited involvement that spontaneously regresses to progressive multiorgan involvement that can be chronic and debilitating. In some cases, the disease can be life-threatening.
In some ways, histiocytosis is similar to cancer and has historically been treated by oncologists with chemotherapy and radiation. Unlike cancer, histiocytosis sometimes goes into remission without treatment.
The cause of LCH is unknown. It may be triggered by an unusual reaction of the immune system from something commonly found in the environment. It is not a known infection or cancer. It is not known to be hereditary or communicable.
Over the years, cancer treatments have been used in patients with histiocytosis. Consequently, hematologists and oncologists, who treat cancer, also treat children with LCH. However, the disease is not cancer. Radiation therapy, if used, is given in much lower doses than that which cancer patients receive.
The vast majority of patients will survive the disease. Some may develop life-long chronic problems, while others remain symptom free. In some cases the disease is fatal. Usually these are very young infants who have a rapid downhill course and do not respond to any known treatment. Whether or not the disease responds to treatment will often depend on the extent of organ involvement; however, it is often difficult to make definite predictions.