Superior Mediastinal Nodes (1-4)

• 1. Highest Mediastinal: above the left brachiocephalic vein.
• 2. Upper Paratracheal: above the aortic arch, but below the left brachiocephalic vein.
• 3. Pre-vascular or Pre-vertebral: these nodes are not adjacent to the trachea like the nodes in station 2. They are either anterior to the vessels (3A) or behind the esophagus, which is prevertebral (3P).
• 4. Lower Paratracheal (including Azygos Nodes): below upper margin of aortic arch down to level of main bronchus.

Aortic Nodes (5-6)

• 5. Subaortic (A-P window): nodes lateral to ligamentum arteriosum. These nodes are not located between the aorta and the pulmonary trunk, but lateral to these vessels.
• 6. Para-aortic (ascending aorta or phrenic): nodes lying anterior and lateral to the ascending aorta and the aortic arch.

Inferior Mediastinal Nodes (7-9)

• 7. Subcarinal.
• 8. Paraesophageal (below carina).
• 9. Pulmonary Ligament: nodes lying within the pulmonary ligaments.

Hilar, Interlobar, Lobar, Segmental and Subsegmental Nodes (10-14)

• 10-14: these are located outside of the mediastinum.
  They are all N1-nodes.

Scroll through the images on the left.

• 1. Highest Mediastinal: above left brachiocephalic vein.
• 2. Upper Paratracheal: below left brachiocephalic vein and above aortic arch.
• 3. Pre-vascular and Retrotracheal : anterior to the vessels (3A) or prevertebral (3P).
• 4. Lower Paratracheal : below upper margin of aortic arch down to level of main bronchus.
• 5. Subaortic (A-P window): nodes lateral to ligamentum arteriosum or lateral to aorta or left pulmonary artery.
• 6. Para-aortic: nodes lying anterior and lateral to the ascending aorta and the aortic arch beneath the upper margin of the aortic arch.
• 7. Subcarinal.
• 8. Paraesophageal (below carina).
• 9. Pulmonary Ligament: nodes lying within the pulmonary ligament.
• 10-14: these nodes are outside of the mediastinum.

Conventional mediastinoscopy

The following nodal stations can be biopsied by cervical mediastinoscopy: the left and right upper paratracheal nodes (station 2L and 2R), left and right lower paratracheal nodes (station 4L and 4R) and the subcarinal nodes (station 7).
Station 1 nodes are located above the suprasternal notch and are not routinely accessed by cervical mediastinoscopy.

Extended mediastinoscopy

Left upper lobe tumors may metastasize to the subaortic lymph nodes (station 5) and paraaortic nodes (station 6).
These nodes can not be biopsied through routine cervical mediastinoscopy.
Extended mediastinoscopy is an alternative for the anterior-second interspace mediastinotomy which is more commonly used for exploration of mediastinal nodal stations.
This procedure is far less easy and therefore less routinely performed than conventional mediastinoscopy.

EUS-FNA

Endoscopic Ultrasound with Fine Needle Aspiration can be performed of all the mediastinal nodes that that can be assessed from the oesophagus.
In addition the left adrenal gland and the left liver lobe can be visualized.
EUS particularly provides access to nodes in the lower mediastinum (station 7,8 and 9)

1. Highest Mediastinal
Nodes located above a horizontal line running along the upper rim of the left brachiocephalic vein, where it crosses in front of the trachea.

On the left a station 1 node.
The brachiocephalic vein is still to the left of the midline.
Therefore this node is above the line where the left brachiocephalic crosses in front of the trachea.

2. Upper Paratracheal
Upper Paratracheal nodes are located below the left brachiocephalic vein and above the upper margin of the aortic arch.

On the left a station 2 node in front of the trachea.
There is also a small prevascular node, i.e. a station 3A node.

3. Prevascular and Prevertabral nodes
Station 3 nodes are not adjacent to the trachea like station 2 nodes.
They are either anterior to the vessels (3A) or behind the esophagus, which lies prevertebrally (3P).

Station 3 nodes are not accessible with mediastinoscopy, however 3P nodes are accessible with endoscopic ultrasound (EUS).

On the left a 3A node in the prevascular space.
Notice also lower paratracheal nodes on the right, i.e. 4R nodes.

4. Lower Paratracheal
The lower paratracheal nodes lie below a horizontal line drawn tangentially to the upper margin of the aortic arch.

4R nodes are lower paratracheal nodes that are located to the right of the midline of the trachea.
They extend down to a horizontal line that runs across the right main bronchus at the upper margin of the upper lobe bronchus.

On the left we see 4R paratracheal nodes.
In addition there is an aortic node lateral to the aortic arch, i.e. station 6 node.

4L nodes are lower paratracheal nodes that are located to the left of the tracheal midline, between a horizontal line drawn tangentially to the upper margin of the aortic arch and a line extending across the left main bronchus at the level of the upper margin of the left upper lobe bronchus.
These include paratracheal nodes that are located medially to the ligamentum arteriosum.
Station 5 (AP-window) nodes are located laterally to the ligamentum arteriosum.

On the left an image just above the level of the pulmonary trunk demonstrating lower paratracheal nodes on the left and on the right.
In addition there are also station 3 and 5 nodes.

On the left an image at the level of the lower trachea just above the carina.
To the left of the trachea 4L nodes.
Notice that these 4L nodes are between the pulmonary trunk and the aorta, but are not located in the AP-window, because they lie medially to the ligamentum arteriosum.
The node lateral to the pulmonary trunk is a station 5 node.

5. Subaortic nodes
Subaortic or aorto-pulmonary window nodes are lateral to the ligamentum arteriosum or the aorta or left pulmonary artery and proximal to the first branch of the left pulmonary artery and lie within the mediastinal pleural envelope.

6. Para-aortic nodes
Para-aortic (ascending aorta or phrenic) nodes are located anteriorly and laterally to the ascending aorta and the aortic arch, below the upper margin of the aortic arch.

7. Subcarinal nodes
These nodes are located caudally to the carina of the trachea, but are not associated with the lower lobe bronchi or arteries within the lung.

On the left a station 7 subcarinal node to the right of the esophagus.

8 Paraesophageal nodes
These nodes are below the carina.
They lie adjacent to the esophageal wall and to the right or left of the midline.
They do not include the subcarinal nodes.

On the left an image below the carina.
To the right of the esophagus a station 8 node.

On the left a PET image demonstrating FDG uptake in a station 8 node.
On the corresponding CT image the node is not enlarged (blue arrow).
The probability that this is a lymph node metastasis is extremely high since the specificity of PET in unenlarged nodes is higher than in enlarged nodes.

9. Pulmonary ligament nodes
Pulmonary ligament nodes are lying within the pulmonary ligament, including those in the posterior wall and lower part of the inferior pulmonary vein.
The pulmonary ligament is the inferior extension of the mediastinal pleural reflections that surround the hila.

10 Hilar nodes
Hilar nodes are proximal lobar nodes, distal to the mediastinal pleural reflection and nodes adjacent to the intermediate bronchus on the right.
Nodes in station 10 - 14 are all N1-nodes, since they are not located in the mediastinum.