Langerhans cell histiocytosis (LCH) is a rare cancer that begins in LCH cells, a type of dendritic cell (white blood cell ). LCH cells can grow in many different parts of the body, where they can damage tissue or form lesions.

LCH may occur at any age but is most common in young children. In infants up to one year of age, LCH may go away without treatment. Treatment of LCH in children is different from treatment of LCH in adults.

LCH in the skin, bones, lymph nodes, or pituitary gland usually gets better with treatment and is called “low-risk.” LCH in the spleen, liver, or bone marrow is harder to treat and is called “high-risk.”