[Langerhans cell histiocytosis in adults].

Langerhans' cell histiocytosis (LCH) encompasses a group of disorders of unknown origin with widely variable clinical presentations and outcomes, characterized by the infiltration of the involved tissues by large numbers of Langerhans cells, often organized into granulomas. In adults, localized LCH involves mainly bones and lungs and usually follows a benign course and can regress spontaneously. The clinical presentation of pluritissular LCH is highly variable depending on the organs involved, mainly bones, skin, lungs, pituitary glands and less commonly liver, spleen, hematopoietic and central nervous system. Multisystemic disease carries a poor prognosis in a number of cases, often necessitates the use of aggressive treatments and may induce permanent sequelae. An international collaborative effort is strongly needed in order to enhance knowledge of the pathogenesis of different forms of LCH and accurately manage patients with this orphan disease in adults.