Part I. Langerhans Cell Histiocytosis: 1. Introduction to the problem: overview, history, epidemiology and classification Sheila Weitzman and R. Maarten Egeler; 2. The histopathology of Langerhans Cell Histiocytosis Ronald Jaffe; 3. Histiocyte function and the normal immune system Tatjana Nikolic and Pieter Leenen; 4. The immunologic basis of Langerhans Cell Histiocytosis Cristiana Costa, Nicola Annels and R Maarten Egeler; 5. The genetics of Langerhans Cell Histiocytosis Maurizio Arico, S. Scappaticci and Cesare Danesino; 6. Clinical aspects of Langerhans Cell Histiocytosis Jean Donadieu, Jon Pritchard and R. Maarten Egeler; 7. Dermatologic aspects of the Histiocytic disorders Bernice Krafchik, Elena Pope and Scott Walsh; 8. Langerhans Cell Histiocytosis of bone Sheila Weitzman and R. Maarten Egeler; 9. Special aspects of Langerhans Cell Histiocytosis in the adult Maurizio Arico, Emanuela De Juli, Thierry Genereau and Alan Saven; 10. Adult lung Histiocytosis Tazi Abdellatif, Jeroen Hiltermann and Roberto Vassallo; 11. Central nervous system involvement in Langerhans Cell Histiocytosis Nicole Grois, Helmut Prosch, Daniela Prayer and Hans Lassmann; 12. The treatment of Langerhans Cell Histiocytosis Helmut Gadner and Stephan Ladisch; 13. Novel and salvage therapies in Langerhans Cell Histiocytosis Sheila Weitzman, Kenneth McClain and Robert Arceci; 14. Late effects of Langerhans Cell Histiocytosis and malignancy and LCH Riccardo Haupt, Vasanta Nanduri and R. Maarten Egeler; 15. Uncommon Histiocytic disorders Sheila Weitzman and James Whitlock; Part II. Histiocytic Disorders Involving the Monocyte/Macrophage Pathway: 16. The histopathology of haemophagocytic lymphohistiocytosis Ronald Jaffe; 17. Genetics and pathogenesis of hemophagocytic lymphohistiocytosis Kim Ericson, Bengt Fadeel and Jan-Inge Henter; 18. Clinical aspects and therapy of hemophagocytic lymphohistiocytosis Gritta Janka, Jan-Inge Henter and Shinsaku Imashuku; 19. Macrophage activation syndrome Ronald Laxer, Athimalaipet Ramanan and Rayfel Schneider; 20. Malignant diseases of the mononuclear phagocytic system David Webb and Penelope Brock; 21. Psychosocial aspects of the Histiocytic disorders Steven Simms, Elizabeth Kuh and Giulio D'Angio.