Langerhans cell histiocytosis (LCH) is a disease formerly known as histiocytosis X with the eosinophilic granuloma subunits, Hand-Schüller-Christian and Letterer-Siwe disease. It is a rare group of diseases with a wide range of clinical symptoms and different biological behaviors.
On the one hand they are solitary bone lesions with a tendency to spontaneous regression and on the other hand they are multisystemic diseases with life-threatening course. In some forms of LCH the role of treatment is debatable, in others aggressive oncological therapy is required.