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For further information, see CMDT Part 9-19: Mediastinal Masses

Key Features

  • Various developmental, neoplastic, infectious, traumatic, and cardiovascular disorders may cause masses that appear in the mediastinum on chest radiograph

  • The mediastinum is divided into three compartments to help classify masses and assist in differential diagnosis

    • The anterior compartment is bounded by the sternum anteriorly and the surface of the great vessels and pericardium posteriorly

    • The middle compartment extends from the anterior pericardium to the anterior surface of the thoracic spine

    • The posterior compartment is paravertebral

  • Specific mediastinal masses have a predilection for one or more of these compartments; most masses are located in the anterior or middle compartment

Clinical Findings

  • Symptoms and signs are nonspecific and usually caused by the effects of the mass on surrounding structures

  • Insidious onset of retrosternal chest pain, dysphagia, or dyspnea is often an important clue to the presence of a mediastinal mass

  • In about half of cases, symptoms are absent, and the mass is detected on routine chest radiograph

  • Physical findings vary depending on the nature and location of the mass

  • Differential diagnosis

    • Anterior mediastinal mass includes

      • Thymoma

      • Teratoma

      • Thyroid lesions

      • Lymphoma

      • Mesenchymal tumors (lipoma, fibroma)

    • Middle mediastinal mass includes

      • Lymphadenopathy

      • Pulmonary artery enlargement

      • Aneurysm of the aorta or innominate artery

      • Developmental cyst (bronchogenic, enteric, pleuropericardial)

      • Dilated azygous or hemiazygous vein

      • Foramen of Morgagni hernia

    • Posterior mediastinal mass includes

      • Hiatal hernia

      • Neurogenic tumor (neurilemmoma, neurofibroma, neurosarcoma, ganglioneuroma, and pheochromocytoma)

      • Meningocele

      • Esophageal tumor

      • Foramen of Bochdalek hernia

      • Thoracic spine disease

      • Extramedullary hematopoiesis


  • CT scanning is helpful in management

  • Additional beneficial radiographic studies include

    • Barium swallow if esophageal disease is suspected

    • Doppler sonography or venography of brachiocephalic veins and the superior vena cava

    • Angiography

  • MRI is useful; its advantages include

    • Better delineation of hilar structures

    • Distinction between vessels and masses

  • Tissue diagnosis via either needle or excisional biopsy is generally necessary when a neoplastic process is considered


  • Depends on the underlying cause of the mediastinal mass

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