Round Atelectasis

ABSTRACTRound atelectasis almost always develops in the presence of pleural effusion. Radiographically, this entity has distinctive features including a rounded configuration, the comet tail sign, curvilinear air bronchograms contained within the mass, associated pleural thickening, lobar volume loss, and surrounding hyperlucency. Round atelectasis usually involves the lower lobes, but may involve any portion of the lung. Once established, round atelectasis may not resolve. Familiarity with the entity of round atelectasis may prevent unnecessary investigation and thoracotomy. We report four patients that illustrate the radiographic findings of round atelectasis.