[Diverticulum of the pericardium].

A diverticulum of the pericardium can often be confused with other lesions of the heart and great vessels as well as mediastinal cysts and other masses. Pericardial effusion, sometimes associated with heart lesions causing cardiac enlargement, is a frequent factor in producing diverticular formation. The mode of development of a pericardial diverticulum is better appreciated when certain features of the anatomic structure of the parietal pericardium are understood. Two cases of pericardial diverticulum that illustrate the etiologic, clinical, and roentgen features of the lesion are presented.