<prompt> Answer this question truthfullyWhich information is available concerning Langerhans cell histiocytosis?  <response>: <reason> Histiocytosis is a general name for a group of syndromes that involve an abnormal increase in the number of immune cells called histiocytes. There are three major classes of histiocytosis: Langerhans cell histiocytosis, which is also called histiocytosis X, malignant histiocytosis syndrome now known as T-cell lymphoma, non-Langerhans cell histiocytosis also known as hemophagocytic syndrome. 