Where Are Chest Lymph Nodes Located?

Chest lymph nodes are scattered throughout the thoracic cavity, from the center of the chest between the lungs all the way out to the chest wall and even within the lung tissue itself. Doctors group them into several broad categories based on their anatomical position: mediastinal nodes in the central compartment, hilar nodes where the airways and blood vessels enter each lung, intrapulmonary nodes embedded within the lungs, and parietal nodes along the chest wall, breastbone, and diaphragm. Understanding where each group sits helps explain how infections spread, how cancers are staged, and why a swollen node in one spot carries different implications than one somewhere else.

The Central Compartment: Mediastinal Lymph Nodes

The mediastinum is the space between the two lungs, running from the breastbone in front to the spine in back and from the thoracic inlet at the top down to the diaphragm. It holds the heart, the great blood vessels, the trachea, and the esophagus, and it is packed with lymph nodes. These mediastinal nodes are the ones most commonly discussed in lung cancer staging and in conditions like sarcoidosis.

Within the mediastinum, nodes cluster around specific landmarks. Upper mediastinal nodes sit near the trachea and are often called paratracheal nodes. They line both sides of the windpipe, though the groups on the right and left sides drain slightly different territories. Further up, near where the trachea enters the chest from the neck, are the highest mediastinal nodes. A group sometimes called pre-vascular nodes sits in front of the great vessels, ahead of the aortic arch.

On the left side of the chest, there are nodes tucked into the space between the aorta and the pulmonary artery, an area called the aortopulmonary window. Surgeons sometimes need to biopsy these nodes specifically to stage left-sided lung cancers, since they can be tricky to reach with standard techniques.¹ Nearby, paraaortic nodes sit along the ascending aorta and the aortic arch itself.

Lower in the mediastinum, a prominent cluster called the subcarinal nodes lies just below the carina, the point where the trachea splits into the right and left main bronchi. On the right side, these nodes extend down to the bottom edge of the intermediate bronchus, while on the left they reach the upper margin of the lower lobe bronchus.² The subcarinal station is one of the most clinically significant in lung cancer because both lungs drain into it, making it a common site for metastatic spread.

Still deeper, paraesophageal nodes run alongside the esophagus, and pulmonary ligament nodes sit at the very base of the lung roots near the diaphragm. Both of these groups are classified as inferior mediastinal nodes.²

Hilar Lymph Nodes

The hilum is the root of each lung, the spot where the main bronchus, the pulmonary artery, and the pulmonary veins enter and exit. Hilar lymph nodes cluster right around these structures. Most of them are arranged along the bronchi, close to the pulmonary vascular branches.³ Because every bit of lymph draining from the lung tissue passes through the hilum on its way to the mediastinum, hilar nodes are often the first to enlarge when something is wrong deeper in the lung.

Hilar enlargement shows up on a standard chest X-ray as a widening or increased density at the lung root. It is one of the more common radiologic findings that prompts further workup. Enlarged hilar nodes can signal lung cancer, lymphoma, infections like tuberculosis, or inflammatory conditions like sarcoidosis. A node at the hilum is not always alarming on its own, but bilateral hilar enlargement in a young adult, for instance, is a classic presentation of sarcoidosis.

Nodes Inside the Lungs

Most people are surprised to learn that lymph nodes exist within the lung tissue itself, not just at the hilum or in the mediastinum. These intrapulmonary lymph nodes (sometimes called interlobar or peribronchial nodes) sit along the branching airways and blood vessels inside the lung. On a CT scan, they typically appear as small, solid nodules with sharp margins, round or oval in shape, located within about 15 mm of the pleural surface. Most are found below the level of the carina.⁴

These nodes matter because they can be mistaken for small lung nodules on imaging. A radiologist who recognizes the typical features of an intrapulmonary lymph node can spare a patient unnecessary biopsies or anxiety. The key giveaway is the combination of their subpleural location, their sharp borders, and the fact that they do not usually calcify.

Chest Wall and Parietal Lymph Nodes

Beyond the lungs and the mediastinum, a separate set of nodes lines the inner surfaces of the chest wall, the area behind the breastbone, and the upper surface of the diaphragm. These parietal lymph nodes include parasternal nodes running along the internal thoracic (mammary) arteries and veins behind the breastbone, intercostal nodes nestled between the ribs near the spine, paravertebral nodes alongside the vertebral column, and diaphragmatic nodes on the upper surface of the diaphragm.⁵ A less commonly discussed group, the paramammary nodes, sits near the lateral edge of the pectoralis major muscle.

The parasternal (internal mammary) nodes are particularly important in breast cancer. They receive lymph drainage from the inner portions of the breast, and whether cancer has spread to them affects treatment decisions. However, their location deep behind the breastbone makes them difficult to biopsy, and imaging is not always reliable for detecting small metastases there. The rate at which these nodes test positive varies widely depending on the imaging method used, and agreement between imaging findings and surgical pathology remains limited.⁶

How Lymph Flows Through the Chest

The chest’s lymph nodes are not just randomly scattered; they are connected by a network of lymphatic vessels that follow predictable drainage routes. Lymph from the lung tissue generally moves outward through intrapulmonary nodes, then to hilar nodes, and finally into the mediastinal nodes before emptying into the large veins at the base of the neck. But this tidy sequence has plenty of shortcuts.

Anatomic studies have shown that some lung segments send lymph directly to mediastinal nodes, bypassing the hilum entirely. In one study of hundreds of adult lung specimens, direct passages from lung segments to mediastinal nodes were found in roughly a quarter of cases on both the right and left sides. These shortcuts were more common from upper lobe segments and less common from the basal segments of the lower lobes.⁷ This is clinically relevant because it means a lung cancer in the upper lobe can sometimes spread to mediastinal nodes without first involving the hilar nodes, a phenomenon called skip metastasis.

Studies using PET/CT imaging in lung cancer patients have confirmed that metastatic lymph nodes almost always fall along these preferential drainage pathways from the tumor-bearing lobe.⁸ Knowing which lobe a tumor sits in helps doctors predict which node stations are most likely involved.

Chest wall lymph also follows its own routes. Lymph from the ribs, their covering membranes, and the intercostal muscles drains to intercostal, parasternal, paravertebral, and diaphragmatic nodes.⁵ These pathways are less discussed in everyday medicine but become important in chest wall tumors or after thoracic surgery.

The Standardized Numbering System

Because there are so many lymph node groups in the chest, doctors use a standardized map to communicate clearly about which nodes they mean. The current international standard is the map published by the International Association for the Study of Lung Cancer (IASLC), which assigns a number to each station.⁹ This map reconciled older, competing systems that had caused confusion when comparing studies from different countries.¹⁰

The stations are numbered 1 through 14, moving roughly from the top of the chest downward and from the mediastinum out into the lungs:

Stations 1–4: Upper mediastinal nodes, including the highest mediastinal, upper and lower paratracheal nodes on both sides.
Stations 5–6: Aortic nodes, including the subaortic (aortopulmonary window) and paraaortic groups on the left side.
Stations 7–9: Lower mediastinal nodes, including the subcarinal, paraesophageal, and pulmonary ligament stations.
Stations 10–11: Hilar and interlobar nodes at the lung root.
Stations 12–14: Peripheral intrapulmonary nodes along the lobar, segmental, and subsegmental bronchi.

This numbering system is used daily in radiology reports, surgical notes, and cancer staging discussions. When a report says “enlarged station 7 node,” it means a swollen subcarinal lymph node. The system has been adopted worldwide and is meant to be used alongside the TNM staging classification for lung cancer.¹¹

What Normal Chest Lymph Nodes Look Like on a CT Scan

Everyone has lymph nodes in their chest, and they show up routinely on CT scans. The question is usually whether they are a normal size or enlarged. A widely used rule of thumb is that a mediastinal lymph node is considered potentially enlarged when its short-axis diameter in the cross-sectional plane exceeds 10 mm.¹²

That said, the “normal” upper limit is not the same at every station. A postmortem study measuring lymph nodes across different mediastinal regions found that subcarinal nodes (station 7) can be up to 12 mm and still be normal, while nodes at most other stations should be 8 mm or smaller. Right lower paratracheal (station 4R) and right hilar (station 10R) nodes can reach up to 10 mm.¹³ Size alone is not a perfect indicator of disease, but it remains the first thing radiologists check.

Why Location Matters for Cancer Staging

In lung cancer, the location of involved lymph nodes directly determines the stage of disease, which in turn shapes treatment. The staging system divides nodal involvement into three tiers based on how far cancer has traveled from the primary tumor. Spread to nodes on the same side as the tumor within the lung or at the hilum is classified as N1. Spread to mediastinal nodes on the same side, or to the subcarinal station, is N2. Spread to the opposite side of the mediastinum, the opposite hilum, or up into the scalene or supraclavicular nodes above the collarbone is N3.¹⁴

The jump from N1 to N2 is one of the most consequential distinctions in thoracic oncology. N1 disease is often still operable, while N2 disease may require chemotherapy or radiation before or instead of surgery. N3 disease generally rules out curative surgery. This is why so much effort goes into precisely identifying which node stations are involved.

How Doctors Sample Chest Lymph Nodes

Getting tissue from a suspicious chest lymph node used to require major surgery. Today, the most common first-line approach is endobronchial ultrasound-guided transbronchial needle aspiration, a mouthful usually shortened to EBUS-TBNA. A thin bronchoscope with an ultrasound probe at the tip is passed through the mouth or nose into the airways, and the doctor uses real-time ultrasound to guide a needle through the airway wall into a nearby lymph node.¹⁵

EBUS can reach most of the mediastinal and hilar stations, but its accuracy is not uniform across all locations. Nodes on the left side of the mediastinum, particularly station 4L (left lower paratracheal), can be harder to sample accurately because of the anatomy of the aortic arch and surrounding structures. One study found that sensitivity and negative predictive value were lower for left-sided nodal groups compared to others.¹⁶ For stations that EBUS cannot reach well, such as the aortopulmonary window and paraaortic nodes (stations 5 and 6), surgeons may turn to mediastinoscopy or video-assisted thoracoscopic surgery.

Non-Cancer Reasons for Enlarged Chest Lymph Nodes

Enlarged mediastinal or hilar lymph nodes do not automatically mean cancer. A variety of infections and inflammatory conditions target the same node groups. Sarcoidosis, an inflammatory disease of unknown cause, classically produces bilateral, symmetric hilar and mediastinal lymphadenopathy. Tuberculosis also enlarges mediastinal nodes, but the pattern tends to be more asymmetric and unilateral. In one comparative study, symmetric bilateral mediastinal involvement was seen in roughly 87% of sarcoidosis cases but only about 24% of tuberculosis cases.¹⁷ Fungal infections, viral illnesses, and occupational dust exposures like silicosis can also cause mediastinal node enlargement.

The pattern of which nodes are enlarged, whether they are on one side or both, whether they are calcified, and whether the lung tissue itself looks abnormal all help doctors narrow the possibilities before any biopsy is performed.

What Happens to Lymphatic Flow After Chest Surgery

When surgeons remove a lobe of the lung for cancer, they typically also remove nearby lymph nodes to check for spread. This disrupts the normal lymphatic plumbing. Lymph that used to flow through those now-absent nodes has to find alternative routes, and sometimes the remaining system gets overwhelmed. The result can be pulmonary lymphedema, a buildup of lymph fluid in the remaining lung tissue. Excessive removal of mediastinal lymph nodes during lobectomy can cause congestion of lymph flow, leading to swelling and impaired gas exchange in the remaining lung.¹⁸

This complication is uncommon but illustrates how tightly integrated the chest’s lymphatic network is. The superficial lymphatic vessels running just beneath the pleura and the deeper vessels along the bronchi form two parallel drainage systems, and both funnel through the hilar and mediastinal nodes. Disrupting enough of those nodes can back up the entire system. Surgeons balance the need for thorough staging against the risk of overtaxing the lymphatic drainage that the patient’s remaining lung depends on.

How Chest Lymph Nodes Form Before Birth

The chest’s lymph nodes begin developing in the fetus from primitive lymph sacs. These sacs are gradually divided by ingrowths of connective tissue that create a mesh of channels and spaces. As the tissue matures, immune cells, especially lymphocytes, pack into these developing structures, transforming them from loose sacs into dense nodes. A surrounding capsule condenses from connective tissue, afferent lymphatic vessels pierce through it, and blood vessels grow into the interior.¹⁹ By the time a baby is born, the basic architecture of the thoracic lymphatic system is in place, though the nodes continue to mature and change in size and composition throughout life. In older adults, lymph nodes throughout the body tend to accumulate more fatty tissue and may shrink somewhat, which is one reason radiologists keep age in mind when evaluating node size on a scan.

1
PubMed. Accessing the aortopulmonary window (#5) and the paraaortic (#6) lymph nodes in patients with non-small cell lung cancer
2
European Society of Radiology (MyESR / EPOS). The importance of imaging in the anatomy and pathology of mediastinal lymph nodes – Section: The inferior mediastinal nodes
3
PubMed. CT anatomy of hilar lymphadenopathy
4
Radiological Society of North America (RSNA) / PubMed Central. Typical CT Features of Intrapulmonary Lymph Nodes: A Review
5
Biomedicine. Micro-macroscopic anatomy of the lymphatic vessels and lymph nodes that form the parietal lymphatic pathways of the human thoracic cavity
6
PubMed Central. Internal mammary lymph node metastasis in breast cancer patients based on anatomical imaging and functional imaging
7
PubMed. Direct lymphatic drainage of lung segments to the mediastinal nodes. An anatomic study on 260 adults
8
PubMed. F-18-FDG-avid lymph node metastasis along preferential lymphatic drainage pathways from the tumor-bearing lung lobe on F-18-FDG PET/CT in patients with non-small-cell lung cancer
9
PubMed. The IASLC lung cancer staging project: a proposal for a new international lymph node map in the forthcoming seventh edition of the TNM classification for lung cancer
10
PubMed. International association for the study of lung cancer (IASLC) lymph node map: radiologic review with CT illustration
11
PubMed Central. The International Association for the Study of Lung Cancer Lymph Node Map: A Radiologic Atlas and Review
12
PubMed. Normal mediastinal lymph nodes: number and size according to American Thoracic Society mapping
13
PubMed. The number and size of normal mediastinal lymph nodes: a postmortem study
14
Radiopaedia. Lung cancer (staging – IASLC 8th edition)
15
PubMed Central. A New Deep Learning-Based Method for Automated Identification of Thoracic Lymph Node Stations in Endobronchial Ultrasound (EBUS): A Proof-of-Concept Study
16
PubMed Central. Nodal stations and diagnostic performances of endobronchial ultrasound-guided transbronchial needle aspiration in patients with non-small cell lung cancer
17
PubMed Central. A Comparison Study of Lymph Node Tuberculosis and Sarcoidosis Involvement to Facilitate Differential Diagnosis and to Establish a Predictive Score for Tuberculosis
18
Journal of Case Reports and Images in Surgery. Postoperative pulmonary lymphedema after lobectomy and mediastinal nodal dissection for lung cancer
19
PubMed. Ontogeny of human fetal lymph nodes