Chest
Volume 128, Issue 4, October 2005, Pages 2893-2909
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Reviews
Tumors of the Mediastinum

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Tumors of the mediastinum represent a wide diversity of disease states. The location and composition of a mass is critical to narrowing the differential diagnosis. The most common causes of an anterior mediastinal mass include the following: thymoma; teratoma; thyroid disease; and lymphoma. Masses of the middle mediastinum are typically congenital cysts, including foregut and pericardial cysts, while those that arise in the posterior mediastinum are often neurogenic tumors. The clinical sequelae of mediastinal masses can range from being asymptomatic to producing symptoms of cough, chest pain, and dyspnea. This article will review the anatomy of the mediastinum as well as the different clinical, radiographic, and prognostic features, and therapeutic options of the most commonly encountered masses.

Section snippets

Thymoma

Thymomas are the most common neoplasm of the anterior mediastinum with an incidence of 0.15 cases per 100,000.6789 Although rare in children, thymomas represent 20% of anterior mediastinal neoplasms in adults.1011

Thymomas as a group have a wide spectrum of histologic diversity and are classified based on cell type predominance as lymphocytic, epithelial, or spindle cell variants. There is a strong association between histologic subtype and invasiveness as well as prognosis.121314 As a result,

Mediastinal GCTs

Mediastinal GCTs are derived from primitive germ cells that fail to migrate completely during early embryonic development.596061 GCTs are found in young adults and represent 15% of anterior mediastinal masses found in adults.2 Malignant GCTs are more common (> 90%) in men. A mediastinal GCT should prompt a search for a primary gonadal malignancy.

GCTs are classified into the following three groups based on cell type: benign teratomas; seminomas; and embryonal tumors. The embryonal tumors, also

Primary Mediastinal Lymphoma

Primary mediastinal lymphoma is a rare entity comprising only 10% of lymphomas in the mediastinum. Lymphoma usually occurs in the anterior mediastinum and is part of more widespread disease. HD represents approximately 50 to 70% of mediastinal lymphomas, while non-Hodgkin lymphoma comprises 15 to 25%.9091 The three most common types of mediastinal lymphoma include nodular sclerosing HD, large B-cell lymphoma, and lymphoblastic lymphoma.2

Mediastinal Cysts

Mediastinal cysts comprise 12 to 20% of mediastinal masses and are found in the middle compartment of the mediastinum.117118119 Despite a similar incidence, children are more often symptomatic at presentation due to compression on the surrounding structures.120 The most common type of mediastinal cyst are foregut cysts, which are derived as an embryonic abnormality, with enterogenous cysts (50 to 70%) and bronchogenic cysts (7 to 15%) being the most common subtypes.2

Bronchogenic Cysts

Bronchogenic cysts are

Neurogenic Tumors

Neurogenic tumors are derived from tissue of the neural crest, including cells of the peripheral, autonomic, and paraganglionic nervous systems. Ninety-five percent of posterior mediastinal masses arise in the intercostal nerve rami or the sympathetic chain region.133 They are classified on the basis of cell type and comprise approximately 12 to 21% of all mediastinal masses, although 95% occur in the posterior compartment.134 Seventy percent to 80% of neurogenic tumors are benign, and nearly

Malignant Tumors of Nerve Sheath Origin

Malignant nerve sheath tumors are spindle cell sarcomas of the posterior mediastinum, and include malignant neurofibromas, malignant schwannomas, and neurogenic fibrosarcomas. They affect men and women equally in the third to fifth decade of life and are closely associated with neurofibromatosis, with a 5% risk of sarcomatous degeneration.141 Pain and nerve deficits are common. Complete surgical resection is the optimal treatment, but, in patients with unresectable tumors, adjuvant chemotherapy

ACKNOWLEDGMENT

We thank the following people for their contributions: Jin Mo Goo, MD, Department of Radiology, Seoul National University College of Medicine, for the contribution of Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 11, which were originally published in the Journal of Computed Assisted Tomography in 2003; Mi-Young Jeung, MD, Department of Radiology, University of Strasbourg, for the contribution of Figures 678910, which were originally published in Radiographics in 2002;

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