Mediastinal mass

Background

• Anatomically delineated into anterior (from sternum to anterior trachea), middle (anterior trachea to just behind the anterior line of the vertebrae), and posterior (essentially overlying the vertebrae all the way to the back)
• Normal structures in the mediastinum include:
  • Anterior: fat, lymph nodes, thymus or thymic remnant, heart, ascending aorta
  • Middle: trachea, bronchi, lymph nodes, esophagus, and descending aorta
  • Posterior: paravertebral soft tissue

Etiologies

Anterior Mediastinal Mass

• Thymic lesion, including thymoma, thymic carcinoma, thymic carcinoid, and thymic cyst
• Lymphoma, particularly Hodgkin disease, mediastinal large cell non-Hodgkin lymphoma, and lymphoblastic non-Hodgkin lymphoma
• Teratoma or dermoid cyst
• Germ cell tumour, including seminoma and non-seminomatous tumour (yolk sac tumour, embryonal carcinoma, and choriocarcinoma)
• Substernal goiter or ectopic thyroid tissue
• Parathyroid adenoma
• Lipoma and liposarcoma
• Fibroma and fibrosarcoma
• Foramen of Morgagni hernia
• Fibrosing mediastinitis, including histoplasmosis and tuberculosis, autoimmune disorders, medication effects, and radiation exposure

Middle Mediastinal Mass

• Pericardial cyst
• Lymphadenopathy from lymphoma, sarcoidosis, or metastatic lung cancer
• Enteric cyst
• Esophageal tumour
• Vascular mass or ectasia

Posterior Mediastinal Mass

• Neurogenic tumour, including neurofibroma, neurilemmoma, neurosarcoma, ganglioneuroma, ganglioneuroblastoma, neuroblastoma, chemodectoma, pheochromocytoma
• Meningoceles
• Thoracic spine lesions, including Pott disease