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Mediastinal Masses

By

Richard W. Light

, MD, Vanderbilt University Medical Center

Last full review/revision Jul 2019| Content last modified Jul 2019
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Mediastinal masses are caused by a variety of cysts and tumors; likely causes differ by patient age and by location of the mass (anterior, middle, or posterior mediastinum). The masses may be asymptomatic (common in adults) or cause obstructive respiratory symptoms (more likely in children). Testing involves CT with biopsy and adjunctive tests as needed. Treatment differs by cause.

Mediastinal masses are divided into those that occur in the anterior, middle, and posterior mediastinum. The anterior mediastinum extends from the sternum to the pericardium in the inferior region and from the sternum to the brachiocephalic vessels in the superior region. The middle mediastinum lies between the anterior and posterior mediastinum. The posterior mediastinum is bounded by the pericardium and trachea anteriorly and the vertebral column posteriorly.

Etiology

Adults

In adults, the most common causes vary by location:

  • Anterior mediastinum: Thymomas and lymphomas (both Hodgkin and non-Hodgkin)

  • Middle mediastinum: Lymph node enlargement and vascular masses

  • Posterior mediastinum: Neurogenic tumors and esophageal abnormalities

For other causes, see figure Some causes of mediastinal masses in adults.

Some causes of mediastinal masses in adults

Some causes of mediastinal masses in adults

Children

In children, the most common mediastinal masses are neurogenic tumors and cysts. For other causes, see table Some Causes of Mediastinal Masses in Children.

Table
icon

Some Causes of Mediastinal Masses in Children

Location

Cause

Anterior

Ectopic thyroid

Sarcoma

Teratoma

Middle

Bronchogenic cyst

Cardiac tumor

Cystic hygroma

Lymphoma

Pericardial cyst

Vascular abnormalities

Posterior

Esophageal duplication

Meningomyelocele

Neuroenteric abnormalities

Neurogenic tumors

Symptoms and Signs

Many mediastinal masses are asymptomatic. In general, malignant lesions and masses in children are much more likely to cause symptoms. The most common symptoms are chest pain and weight loss. Lymphomas may manifest with fever and weight loss.

In children, mediastinal masses are more likely to cause tracheobronchial compression and stridor or symptoms of recurrent bronchitis or pneumonia.

Symptoms and signs also depend on location. Large anterior mediastinal masses may cause dyspnea when patients are lying supine. Lesions in the middle mediastinum may compress blood vessels or airways, causing the superior vena cava syndrome or airway obstruction. Lesions in the posterior mediastinum may encroach on the esophagus, causing dysphagia or odynophagia.

Diagnosis

  • Chest x-ray

  • CT and sometimes MRI

  • Sometimes tissue examination

Mediastinal masses are most often incidentally discovered on chest x-ray or other imaging tests during an examination for chest symptoms. Additional diagnostic testing, usually imaging and biopsy, is indicated to determine etiology.

CT with IV contrast is the most valuable imaging technique. With thoracic CT, normal variants and benign tumors, such as fat- and fluid-filled cysts, can be distinguished from other processes. An MRI is done if the structure is cystic. MRI may be useful in determining whether the mass is compressing or invading adjacent structures.

A definitive diagnosis can be obtained for many mediastinal masses with needle aspiration or needle biopsy. Fine-needle aspiration techniques usually suffice for carcinomatous lesions, but a cutting-needle biopsy should be done whenever lymphoma, thymoma, or a neural mass is suspected. If ectopic thyroid tissue is considered, thyroid-stimulating hormone is measured.

Treatment

  • Depends on cause

Treatment depends on etiology. Some benign lesions, such as pericardial cysts, can be observed. Most malignant tumors should be removed surgically, but some, such as lymphomas, are best treated with chemotherapy. Granulomatous disease should be treated with the appropriate antimicrobial drug.

Key Points

  • In adults, thymomas and lymphomas (both Hodgkin and non-Hodgkin) are the most common anterior lesions, lymph node enlargement and vascular masses are the most common middle lesions, and neurogenic tumors and esophageal abnormalities are the most common posterior lesions.

  • In children, the most common mediastinal masses are neurogenic tumors and cysts.

  • The most common symptoms are chest pain and weight loss, but many masses are asymptomatic.

  • Obstructive respiratory symptoms can occur in children and rarely in adults.

  • CT with IV contrast is the most valuable imaging technique.

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