Langerhans cell histiocytosis (LCH) is a rare disorder that occurs when a child has too many of a certain cell type called Langerhans cells. These cells usually are in the skin and help fight infection and destroy foreign substances in the body. In LCH, extra Langerhans cells spread through the blood and build up in certain parts of the body, where they can damage tissue or form tumors.
In LCH, Langerhans cells typically accumulate in bones but can also accumulate in the skin, lymph nodes, liver, spleen, lung, or brain. Scientists do not agree on whether LCH is a type of cancer or a condition caused by a change in the immune system. However, recent studies by scientists at Dana-Farber Cancer Institute have demonstrated a mutant oncogene, BRAF V600E, in more than half of LCH biopsy samples. This suggests that LCH is a type of neoplastic disease (a disease grouping that includes benign, pre-cancerous, and cancerous growths).
LCH may occur at any age, but is most common in children under 10.