Left hilar mass with obstruction of the main bronchus due to localized pseudoaneurysm of the thoracic aorta.

The left hilum is an anatomically complex region. It is poorly imaged on conventional chest roentgenography and even on tomography. A wide range of diagnoses must be considered upon discovery of a hilar mass. In this report, the authors discuss their experience with a potentially hazardous hilar mass found in a 61-year-old man with a 40 pack-year smoking history. The mass, which was identified as an aortic pseudoaneurysm, caused near-total obstruction of the left main bronchus. The aneurysm was successfully repaired and patency of the bronchus restored. Radiographic features that suggest an aortic aneurysm as a cause of a hilar mass include posterior location and lack of associated mediastinal or contralateral hilar adenopathy. Computer tomography with contrast will readily define a vascular hilar mass. If cancer or lymphoma are suspected as the cause of a hilar mass, mediastinal lymph-node imaging, and aspiration or biopsy are indicated.