U01.16.029 Mediastinal Pathology

The mediastinum is the central compartment of the thoracic cavity, containing essential structures such as the heart, thymus, lymph nodes, esophagus, and aorta.

Mediastinal Masses

Mediastinal masses can occur in any of the three compartments of the mediastinum: anterior, middle, and posterior. The most common pathologies associated with each compartment are as follows:

Common Mediastinal Masses by Compartment:

Compartment	Common Pathologies
Anterior	Thyroid (substernal goiter), Thymic neoplasm, Teratoma, “Terrible” lymphoma
Middle	Esophageal carcinoma, Metastases, Hiatal hernia, Bronchogenic cysts
Posterior	Neurogenic tumor (e.g., neurofibroma), Multiple myeloma

Common Mediastinal Masses by Compartment:

Mediastinitis

Mediastinitis is the inflammation of mediastinal tissues, commonly resulting from postoperative complications following cardiothoracic procedures, esophageal perforation, or the spread of odontogenic or retropharyngeal infections.

Types of Mediastinitis:

Acute Mediastinitis: Often occurs within 14 days post-surgery and is associated with fever, tachycardia, leukocytosis, chest pain, and sternal wound drainage.
Chronic Mediastinitis (Fibrosing Mediastinitis): Characterized by the proliferation of connective tissue within the mediastinum, with Histoplasma capsulatum being a common cause.

Pneumomediastinum

Pneumomediastinum is the presence of gas (usually air) within the mediastinum. It can be:

Spontaneous: Often due to the rupture of a pulmonary bleb.
Secondary: Results from trauma, iatrogenic causes, or Boerhaave syndrome.

Clinical Features of Pneumomediastinum:

Chest pain
Dyspnea
Voice change
Subcutaneous emphysema
Positive Hamman sign (crepitus on cardiac auscultation)

Points to Remember:

Anterior mediastinal masses are commonly associated with the “4 T’s”: Thyroid, Thymic neoplasm, Teratoma, and “Terrible” lymphoma.
Mediastinitis can present acutely after cardiothoracic surgery or develop chronically, often due to infection with Histoplasma capsulatum.
Pneumomediastinum should be suspected in patients with chest pain and subcutaneous emphysema, particularly if the Hamman sign is present.

Bibliography:

Shields, T.W., et al. (2022). General Thoracic Surgery. 8th ed. Lippincott Williams & Wilkins.
Iyer, P. & Lee, D. (2020). Mediastinal Masses: A Review of Essential Clinical, Imaging, and Pathologic Features. Journal of Thoracic Imaging, 35(5), 312-321.
Johnson, J.M. & McAdams, H.P. (2019). Mediastinitis: Radiologic-Pathologic Correlation. Radiographics, 39(7), 1943-1956.

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