Mediastinal Compartments and Diagnostic Approaches

Introduction to Mediastinal Compartments

The American College of Radiology recommends dividing the mediastinum into three compartments: prevascular, visceral, and paravertebral, to better reflect anatomical relationships visible on cross-sectional imaging 1
The prevascular compartment is the primary site for thymic epithelial tumors, germ cell tumors, and lymphomas, with thymomas being the most common lesion (28%) 1
The visceral compartment contains vital structures including the heart, great vessels, trachea, and esophagus, and benign cysts are the most common lesions in this compartment 1

The National Comprehensive Cancer Network recommends CT chest with contrast as the primary imaging modality for evaluating mediastinal masses 2
MRI provides additional tissue characterization that may prevent unnecessary biopsies, according to the American College of Radiology 1
PET-CT is optional but can help differentiate between benign and malignant disease, as suggested by the National Comprehensive Cancer Network 2
Specific serum markers (beta-HCG, AFP) may help identify germ cell tumors, according to the National Comprehensive Cancer Network 2

The National Comprehensive Cancer Network and Annals of Oncology suggest that minimally invasive approaches are increasingly used but may not be appropriate for all cases, and complete resection is the goal for mediastinal tumors, particularly thymic epithelial tumors 2, 3
Mediastinoscopy provides access to lymph nodes in the visceral compartment but cannot access the paravertebral compartment or anterior mediastinal (station 6) nodes, as noted by Chest 4
Failure to perform appropriate lymphadenectomy during resection of thymic tumors may affect staging accuracy, according to Annals of Oncology 3

The surface landmarks of the visceral (middle) compartment are located between the anterior and posterior axillary lines 5
The anterior axillary line is marked by the intersection of the posterior border of Pectoralis Major and the 2nd rib 5
The posterior axillary line is marked by the posterior border of Pectoralis Major 5
The paravertebral (posterior) compartment is located posterior to the posterior axillary line 5
The paravertebral (posterior) compartment can be defined as 2/3rds of the circumference between the costochondral junction and the costotransverse joint 5
There is no universally accepted nomenclature to describe the exact borders of each region of the mediastinum 5

The suprasternal notch view allows visualization of the aortic arch and great vessels by placing the probe in the suprasternal notch, directed inferiorly into the mediastinum 6
Awareness of internal mammary vessels is crucial for safely performing the parasternal approach 7
Mediastinoscopy provides access to lymph nodes in the visceral compartment but cannot access the paravertebral compartment or anterior mediastinal (station 6) nodes 8

Understanding the relationship between surface landmarks and underlying structures is crucial to avoid damage to vital structures during surgical approaches 7

Accurate staging of lung cancer is crucial and understanding mediastinal compartments is important for this purpose, as stated by the American College of Chest Physicians, with a recommendation for accurate staging of lung cancer 9, 10