May Be Caused by

Abnormal vascular impression on esophagus

Aortic knob

Bronchogenic duplication cyst

Cardiomegaly

Confluence of left pulmonary veins

Diffuse idiopathic skeletal hyperostosis

Enteric duplication cyst

Hiatal hernia

Kyphosis

Left atrial enlargement

Left main stem bronchus

Mediastinal cyst

Mediastinal lymphadenopathy

Mediastinal tumor

Mediastinitis

Osteophyte

Pericardial cyst

Pericardial effusion

Pericardial tumor

Pleuropulmonary fibrosis at lung apex

Pulmonary mass

Schwannoma of phrenic nerve

Schwannoma of vagus nerve

Scoliosis

Spinal neoplasm

Spinal osteomyelitis

Tracheal neoplasm