Pulmonary eosinophilic granuloma or histiocytosis X is a chronic interstitial lung disease characterized by proliferations of Langerhans cells and, therefore, not truly histiocytosis. Both histiocytes and Langerhans cells are believed to be related to the mononuclear phagocyte system. In Eosinophilic granuloma, extra-pulmonary such as mediastinal or hilar lymph nodes involvement is very rare in adult. We report a case of young man with eosinophilic granuloma involving lung and anterior mediastinal lymph node simultaneously which is confirmed by open thoracotomy.