May Be Caused by

 Common

Achalasia

AIDS

Azygos continuation of inferior vena cava

Bronchogenic cyst

Castleman disease

Descending aorta dilatation

Dilated azygos vein

Duplication cyst

Esophageal carcinoma

Esophageal dilatation

Histoplasmosis

Inferior vena cava obstruction

Left atrial enlargement

Lung cancer

Lymphoma

Metastasis

Paraesophageal lymphadenopathy

Sarcoidosis

Subcarinal lymphadenopathy

Superior vena cava syndrome

Tuberculosis

 Uncommon

Alveolar lung disease

Esophageal varices

Localized fibrous tumor of pleura

Pleural effusion or thickening

Pleural mesothelioma

Pleural metastasis

Pulmonary atelectasis