Mediastinal mass

Mediastinal mass Microchapters
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Overview
Anatomy of Mediastinum
Causes
Differentiating Mediastinal Mass from other Diseases

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Trusha Tank, M.D.[2]

Synonyms and keywords: Mediastinal enlargement; mass in the mediastinum

Overview

The mediastinum is a non-delineated group of structures in the thorax (chest), surrounded by loose connective tissue. It is the central compartment of the thoracic cavity. It contains the heart, the great vessels of the heart, esophagus, trachea, thymus, and lymph nodes of the central chest. A wide variety of diseases involving these organs can present as a mediastinal mass or widening of the mediastinum on imaging studies. Mediastinal widening is diagnosed by the mediastinum measuring greater than 8 cm in width on PA chest x-ray. The mediastinal mass may present with symptoms caused by the mass pressing against other mediastinal structures or even without any symptoms. Mediastinal masses can be differentiated on the basis of location in the mediastinal cavity into 3 groups: Prevascular, visceral and paravertebral.

Anatomy of mediastinum

Anatomically, mediastinal cavity is divided into following compartments:

• Prevascular (anterior)
• Visceral (middle)
• Paravertebral (posterior)

International Thymic Malignancy Interest Group (ITMIG) Classification of Mediastinum
Compartments	Boundaries	Components
Prevascular	Superior: Thoracic inlet Inferior: Diaphragm Anterior: Sternum Posterior: Anterior aspect of the pericardium Lateral: Parietal mediastinal pleura	Thymus Fat Lymph nodes Left brachiocephalic vein
Visceral	Superior: Thoracic inlet Inferior: Diaphragm Anterior: Posterior boundaries of the prevascular compartment Posterior: Vertical line connecting a point on each thoracic vertebral body 1 cm posterior to its origin	Non vascular: Trachea Carina Esophagus Lymph nodes Vascular: Heart Ascending thoracic aorta Aortic arch Descending thoracic aorta Superior vena cava Intrapericardial pulmonary arteries Thoracic duct
Paravertebral	Superior: Thoracic inlet Inferior: Diaphragm Anterior: Posterior boundaries of the visceral compartment Posterolateral: Vertical line against the posterior margin of the chest wall at the lateral margin of the transverse process of the thoracic spine	Thoracic spine Paravertebral soft tissues
Adapted from Radiographics