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Mediastinal Masses

by Richard W. Light, MD

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 (in adults) or cause obstructive respiratory symptoms (in children). Testing involves CT with biopsy and adjunctive tests as needed. Treatment differs by cause.

Etiology

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 and brachiocephalic vessels posteriorly. 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.

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.


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.

Some Causes of Mediastinal Masses in Children

Location

Cause

Anterior

Ectopic thyroid

Lymphoma

Sarcoma

Teratoma

Middle

Bronchogenic cyst

Cardiac tumor

Cystic hygroma

Lymphadenopathy

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

  • 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.

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.

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

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