Thoracic Lymph Nodes

Published on 13/02/2015 by admin

Filed under Cardiothoracic Surgery

Last modified 22/04/2025

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Thoracic Lymph Nodes

Lymph Nodes Axial 1

Diagnostic Consideration

Thoracic CT plays a major role in the evaluation of patients with suspected pulmonary malignancy. In particular, one major role for thoracic CT for patients with pulmonary malignancy is the depiction of hilar, mediastinal, and intrapulmonary lymph node enlargement. Correct identification and classification of lymph node locations is critical for accurate staging for lung cancer patients as well as numerous other thoracic diseases. Intrathoracic lymph nodes are commonly referred to in clinical practice using descriptive terms, although a widely accepted lymph node classification system, set forth by the American Joint Committee on Cancer (AJCC) and International Union Against Lung Cancer (UICC), is often used to standardize reporting of lymph node involvement in lung cancer patients. Although an extensive review of thoracic lymph node classifications is beyond the scope of this work, several images illustrating locations of abnormal lymph nodes in a patient with sarcoidosis will be reviewed. In this system, the designation “R” and “L” refers to “right” and “left” of midline, respectively.

Enlarged lymph nodes is seen just anterior and to the right of the trachea; this region is often referred to as the “right paratracheal space.” In the AJCC classification system, lymph nodes in this location are referred to as “upper paratracheal lymph nodes” (station 2); these lymph nodes lie inferior to the cranial margin of the left brachiocephalic vein, where this vein crosses anterior to the trachea, and superior to the cranial margin of the aortic arch.

Lymph Nodes Axial 2

Diagnostic Consideration

A focus of high attenuation is present within the mildly enlarged right paratracheal lymph node; this high-attenuation focus represents calcification, which is a common occurrence in patients with sarcoidosis. In the AJCC lymph node classification, this lymph node is considered a “lower paratracheal lymph node (station 4).” This lymph node lies inferior to the cranial aspect of the aortic arch and cranial to the superior margin of the right upper lobe bronchus.

Lymph Nodes Axial 3

Diagnostic Consideration

High-attenuation foci are present in both lower paratracheal lymph nodes visible in this section, very faint within the right-sided lymph node. One lower paratracheal lymph node lies to the right of midline, whereas another lymph node lies to the left of midline—station 4R and 4L lymph nodes, respectively, in the AJCC lymph node classification system. Lower paratracheal (station 4) lymph nodes lie inferior to the cranial aspect of the aortic arch and cranial to the superior margin of the right upper lobe bronchus.

In this section, the calcified ligamentum arteriosum is visible. This is an important anatomical landmark because paratracheal lymph nodes lie medial to this structure and may be sampled with cervical mediastinoscopy, whereas prevascular, subaortic, and aortopulmonary window lymph nodes lie lateral to the ligamentum arteriosum and are not accessible with standard cervical mediastinoscopy.

Lymph Nodes Axial 4

Diagnostic Consideration

High-attenuation foci, representing calcification, are readily visible within the right and left lower paratracheal lymph nodes. These nodes are accessible with cervical mediastinoscopy.

Lymph Nodes Axial 5

Diagnostic Consideration

Right hilar lymph nodes, station 10R in the AJCC lymph node classification system, are visible. Hilar lymph nodes are located caudal to the cranial portion of the right upper lobe bronchus and lie adjacent to the right mainstem bronchus and proximal bronchus intermedius. Hilar lymph nodes are located distal to the mediastinal pleural reflection. In other words, hilar lymph nodes, station 10 lymph nodes, as well as station 11-14 lymph nodes lie within the lung. In contrast, lymph nodes located in stations 1-9 in the AJCC lymph node classification system reside within the mediastinum. In patients with lung carcinoma, mediastinal lymph node involvement confers a worse prognosis compared with involved lymph nodes that reside within the lung.

In this image, a subaortic lymph node (station 5) is also visible. These lymph nodes lie lateral to the ligamentum arteriosum and medial to the origin of the first branch of the left pulmonary artery.

Lymph Nodes Axial 6

Diagnostic Consideration

With views progressively caudal to the pulmonary hilum, lymph nodes are consistently closely related to the pulmonary arteries. A calcified right interlobar lymph node (station 11R) is visible. The contour abnormality created by right hilar lymphadenopathy on chest radiographs is often caused by a combination of enlarged lymph nodes in the right hilar (station 10) and right interlobar (station 11) regions. Subcarinal lymph nodes (station 7), which reside within the mediastinum, are visible.

Lymph Nodes Axial 7

Diagnostic Consideration

This view is caudal to the foregoing images (Axial 1-6). Note how lymph nodes are closely associated with the pulmonary arteries. In the lower lobes, lymph nodes are often positioned medial to the adjacent pulmonary arteries and lateral to the bronchi.

Lymph Nodes Axial 8

Diagnostic Consideration

At this level, segmental lymph nodes (station 13R) are seen just lateral to the lateral segmental right middle lobe bronchus, and lobar lymph nodes (station 12R) are seen adjacent to the right lower lobe bronchus. On the left, calcified interlobar lymph nodes (station 11L) are seen. Interlobar lymph nodes are typically found adjacent to and between proximal lobar bronchi. On the left, typically between the lingular and superior segmental bronchi.

Lymph Nodes Axial 9

Diagnostic Consideration

Left inferior pulmonary ligament lymph nodes are visible. A small area of high attenuation, representing calcification, is visible within the lymph node. Inferior pulmonary ligament lymph nodes, also often referred to as pulmonary ligament lymph nodes, are usually found slightly medial and inferior to the inferior pulmonary veins.

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