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

Diagnosis

• 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

Treatment

• Depends on the underlying cause of the mediastinal mass