The retrotracheal triangle.

The retrotracheal triangle is an area in the posterior superior mediastinum where abnormal structures may be detected in as many as 2% of chest radiographs. The authors describe the anatomy of this space and the abnormalities found therein, including vascular abnormalities (aberrant right subclavian artery, right aortic arch, double aortic arch, true and false aortic aneurysms), thoracic duct lesions, esophageal abnormalities (benign and malignant tumors, congenital atresia, duplication cysts, foreign bodies, diverticula, and achalasia), and miscellaneous entities (intrathoracic thyroid, bronchogenic cyst, bronchogenic carcinoma, cystic hygroma, and emphysema). Careful attention to this long-neglected area on chest radiographs can yield findings of abnormalities not otherwise suspected.