Controversies and new approaches to treatment of Langerhans cell histiocytosis

There continues to be genuine ambivalence as to whether Langerhans cell histiocytosis (LCH) is a primary neoplastic or immunodysregulatory disorder. Treatment strategies have moved from one camp to the other depending upon the most current alleged successes or failures. This has been particularly true for patients who fall outside of the sphere where treatment is minimal or where known treatment approaches are clearly beneficial. However, there is growing evidence that LCH is both the result of clonal proliferation of Langerhans cells and the immunologic consequence of increased cellular activation. This new knowledge should be the basis for the development of new therapeutic approaches for patients with LCH and its complications.