Pericardial pseudotumor. Echocardiographic observation of juxtacardiac pulmonary collapse.

Despite its value in the diagnosis of pericardial disease, two-dimensional echocardiography also is known to produce confounding results. Ten patients had juxtacardiac masses simulating pericardial tumor implants on echocardiographic examination ("pericardial pseudotumor") caused by juxtacardiac pulmonary atelectasis or lobar collapse. The atelectatic nature of these masses was based on echocardiographic delineation of pericardial and pleural anatomy, combined with ancillary radiographic and CT studies. Drainage of pleural fluid also led to disappearance of the masses on echocardiographic examination, suggesting that the masses were an ultrasonic manifestation of pulmonary atelectasis resulting from surrounding compressive effusive fluid. Finally, clinical follow-up failed to show development of malignant disease in any patient. The possibility of pericardial pseudotumor should be considered when ultrasound studies show juxtacardiac masses within large collections of pleural fluid, especially in the clinical absence of malignant disease.