Pulmonary lesions mimicking pericardial effusion on ultrasonography

Two children with right middle lobe lesions mimicking pericardial effusion on ultrasonography are presented. They were admitted with fever and chest radiographs showed atelectasis or consolidation of the middle lobe of the right lung along the right heart border. A low-echogenic layer suggesting pericardial fluid was seen on ultrasonography, but with a spatial distribution closely corresponding to the lesions seen on the chest radiographs. If the possibility that a lung lesion adjacent to the heart can simulate pericardial fluid on ultrasonography is kept in mind, the correct diagnosis should not be difficult to make.