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Mediastinal
masses are caused by a variety of cysts and tumors; likely causes
differ by patient age and by whether the mass occurs in the anterior,
middle, or posterior mediastinum. The masses may be asymptomatic
(in adults) or cause obstructive respiratory symptoms (in children). Testing
involves CT scan 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, 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. Other causes are shown in Fig. 1: Mediastinal and Pleural Disorders: 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 1: Mediastinal and Pleural Disorders: Some Causes of Mediastinal Masses in Children .
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 present 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 on lying supine. Lesions in the middle mediastinum may compress blood vessels or airways, producing the superior vena cava syndrome or airway obstruction. Lesions in the posterior mediastinum may encroach on the esophagus, producing dysphagia or odynophagia.
Diagnosis
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 scanning 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 (see Fig. 1: Mediastinal and Pleural Disorders: Some causes of mediastinal masses in adults. and Table 1: Mediastinal and Pleural Disorders: Some Causes of Mediastinal Masses in Children). If ectopic thyroid tissue is considered, thyroid-stimulating hormone is measured.
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Table 1
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Some
Causes of Mediastinal Masses in Children
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Location
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Cause
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Anterior
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Ectopic thyroid
Lymphoma
Sarcoma
Teratoma
In thymus:
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Middle
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Bronchogenic cyst
Cardiac tumor
Cystic hygroma
Lymphadenopathy
Lymphoma
Pericardial cyst
Vascular abnormalities
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Posterior
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Esophageal duplication
Meningomyelocele
Neuroenteric abnormalities
Neurogenic tumors
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Treatment
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.
Last full review/revision February 2008 by Richard W. Light, MD
Content last modified February 2008
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