May Be Caused by

 Common

Acute mediastinitis

Aortic arch anomaly

Aortic dilatation

Bleeding tendency

Bronchogenic duplication cyst

Cushing syndrome

Enteric duplication cyst

Esophageal dilatation

Fat deposition

Hydatid cyst

Leukemia

Lipomatosis

Lymphadenopathy

Lymphoma

Mediastinal abscess

Mediastinal cyst

Mixed germ cell tumor

Neurenteric duplication cyst

Neuroblastoma

Obesity

Post-treatment thymic rebound

Right aortic arch

Steroid medication

Teratoma

Thymic cyst

Thymic hyperplasia

Thymoma

Traumatic hemorrhage

 Uncommon

Anomalous left superior vena cava

Arteriovenous fistulas

Cervical aorta

Dilated azygos vein

High aortic arch

Intrathoracic goiter

Lymphangioma

Pseudocoarctation

Superior vena cava syndrome

Thyroid carcinoma

Thyroiditis

Total anomalous pulmonary venous return

Zenker diverticulum