[Congenital absence of left pericardium simulating tumor of the anterior mediastinum].

The authors report a case of a patient presenting atypical dyspnea symptom. The physical examination, the chest roentgenogram and EKG were abnormal; the echocardiogram showed an abnormal mass compressing the outflow tract of the right ventricle (RV). These data were confirmed by a computerized tomography. The cardiac catheterization showed a heart deviation to the left and a RV outflow tract gradient of 10 mmHg. Consequently a surgery was necessary. The surgical findings presented an absence of the left pericardium and no tumor was found. This is a rare entity that may be misdiagnosed as other heart diseases but this is the first case in which a tumor of the anterior mediastinum was suspected.