<prompt> Air bronchogram sign is seen in?Lung abscessConsolidationCavityPneumothorax  <response>: ANSWER: B ConsolidationREF: Grainger 4th e p. 311, Wolfgang 5th e p. 421, chapman 4th e p. 124,142Air bronchogram is a reliable sign of intrapulmonary pathology for which consolidation is most common cause.Causes of Air BronchogramInfective PneumoniaInflammatory Radiation pneumonitis Progressive massive fibrosis Edema Fat embolismNeoplastic Alveolar ca Lymphoma Lympho sarcoma Metastasis Kaposi sarcomaBlood in lungs Infarction Contusion DIC anticoagulants 