Computed tomography reveals atypical localization of benign mediastinal tumors.

Computed tomographic appearances of 147 surgically proven mediastinal tumors (113 benign and 34 malignant lesions) were evaluated paying special attention to their localization or extension. Ten of the 113 benign lesions (9%) showed atypical or unique localization or extension, and were divided into three groups. In the first group, two lymphangiomas and one bronchogenic cyst spread over both the precardiovascular and the retrocardiovascular compartments, mimicking a malignant lesion. In the second group, the single cases of thymic hypertrophy, thymic cyst, schwannoma, and pericardial cyst were located atypically in the retrocardiovascular compartment. In the last group, two esophageal leiomyomas and one esophageal duplication showed upward and downward longitudinal extension beyond the azygos arch and the aortic arch.