The aim of this work is a systematic study of orphan (rare) lung diseases in Pediatrics as congenital cystic lung disease, congenital central hypoventilation. syndrome, bronchiolitis obliterans, pulmonary alveolar proteinosis, pulmonary papillomatosis., bronchiectasis of unknown, cause, pulmonary lymphangiectasia, idiopathic pulmonary haemosiderosis, and Interstitial lung disease regarding definition, incidence, clinical picture, diagnosis and management.