May Cause

Retrosternal mass

May Be Caused by

 Common

Ascending aorta aneurysm

Brachiocephalic artery aneurysm

Brachiocephalic artery buckling

Brachiocephalic artery dilatation

Cushing syndrome

Germ cell tumor

Hematoma

Hepatic hernia

Hibernoma

Intrapericardial hernia

Intrathoracic adenomatous goiter

Leukemia

Lipomatosis

Lymphoma

Morgagni hernia

Nodular sclerosing Hodgkin disease

Normal epicardial fat pad

Obesity

Pericardial cyst

Pericardial disease

Sinus of Valsalva aneurysm

Steroid medication

Superior vena cava dilatation

Thymic hyperplasia

Thymic mass

Thyroid mass

 Uncommon

Acute mediastinitis

Angiosarcoma

Anomalous left superior vena cava

Bronchogenic cyst

Cardiac tumor

Epithelioid hemangioendothelioma

Fibrosarcoma

Fibrosing mediastinitis

Gastrointestinal stromal tumor

Hemangioma

Hemangiopericytoma

Hydatid cyst

Lipoma

Liposarcoma

Lymphangioma

Lymphangiomatosis

Malignant fibrous histiocytoma

Malignant germ cell neoplasm

Mature teratoma

Mediastinal abscess

Mediastinal lymphadenopathy

Mesothelioma

Metastasis

Parathyroid adenoma

Parathyroid carcinoma

Perforated central venous catheter

Pericardial lipoma

Postoperative fluid collection

Schwannoma

Thymic cyst

Thymolipoma

Thymoma

Ventricular aneurysm