Thread of the lung: anatomy and abnormalities


The neck of a lung is a wedge-shaped area in the center of each lung, located on the medial (middle) side of each lung . In the hilar region, the bronchi , arteries, veins, and nerves enter and exit the lungs.

This area can be difficult to visualize on a chest x-ray, and additional tests, such as computed tomography (CT) (which sometimes require a contrast medium, but not always), are often required to determine if the problem is present. Present.

Hilum enlargement can be due to tumors (such as lung cancer), pulmonary hypertension, or enlarged intrathoracic lymph nodes due to conditions such as infections (especially tuberculosis and fungal infections), cancer (local or metastatic), sarcoidosis, etc. …

Teresa Chiechi / Get Drug Information

Hilum's anatomy

Both the right and left lungs have a collar, which is located about the middle of the lungs and slightly closer to the back (closer to the vertebrae than to the front of the chest). Each lung can be visualized with an apex (top), a base (bottom), a root, and a hilum.

The main bronchi, pulmonary arteries, pulmonary veins, and nerves are structures that enter and exit the lungs in this area. Lymph nodes called hilar lymph nodes are also present in this area. Both hili are of similar size, with the left hilum generally slightly higher on the chest than the right hilum.

Tests to evaluate Hilum

Door abnormalities are usually detected on imaging studies, but additional tests and procedures are often required to determine if and where the problem is.


On a chest X-ray, a shadow is seen at the root, consisting of a combination of lymph nodes, pulmonary arteries, and pulmonary veins.

Due to the overlap of these structures, it is sometimes difficult to detect the enlargement of these lymph nodes or the presence of a mass in this area. This is one of the reasons that a regular chest X-ray can miss lung cancer .

Chest CT (with or without contrast) can improve the visualization of these structures. Positron emission tomography (PET) is sometimes very helpful if a tumor is suspected.

Radiology report

When the radiologist examines the door, they will report if there is symmetry between the right and left door, as well as the following:

  • Shape : bifurcation (blood vessels) is normal.
  • Radiopacity : The hilum is usually denser in the center, with a darker periphery on chest x-ray or CT scan.
  • Proportional size : the majority (approximately two-thirds) of the vascular density should be at the bottom of the hilum.
  • Absolute Size – Any door enlargement will be seen, but most of the time, a significant magnification is required.

Depending on the specific study, the radiologist may notice an enlargement of the hilar nodes and the presence of a hilar mass or hilar lymphadenopathy (enlargement of the hilar lymph nodes).


In addition to imaging tests, abnormalities in the hilar region can be identified with tests such as bronchoscopy , a test in which a tube is inserted through the mouth and down into the main airways (bronchi).

Ultrasound, which is done with an ultrasound probe inserted during bronchoscopy ( endobronchial ultrasound ), sometimes produces samples of abnormal tissue found near the main airways.

A test called mediastinoscopy (a surgical procedure in which the surgeon can examine the area between the lungs, including the hilar lymph nodes) may be needed to better visualize the area or to obtain a biopsy sample, although emission scans Positrons have replaced the need for this procedure in many cases .

Spinning enlargement

The hilar region of the lung may have tumors (including primary and metastatic tumors), enlarged hilar lymph nodes, or abnormalities of the pulmonary arteries or veins.


An enlarged gate can be seen on visual exams to assess symptoms such as a persistent cough, coughing up blood, shortness of breath, or recurrent respiratory infections, or it may be accidentally detected on an exam such as a CT scan. Both tumors and enlarged lymph nodes can be caused by cancer or benign causes .

Location of neoplasms or lymphadenopathy

Some obvious door abnormalities can be caused simply by positioning, and a closer inspection can rule out problems. If education or enlargement is noted, the possible causes may vary based on appearance:

  • Symmetric (bilateral) enlargement: An enlargement of both hilar regions may indicate conditions such as sarcoidosis or pulmonary hypertension .
  • Asymmetric (Unilateral) Enlargement – When only one root area is enlarged, causes such as tumors are more likely .
  • Displacement : The hilar region can move (be in a different position than usual) in conditions such as pneumothorax .


There are four main reasons why the hilum of one or both lungs may appear enlarged on an X-ray. These include :

  • Tumors and lymphadenopathy . Cancers such as lung cancer and lymphoma, as well as cancer that has spread to this area from other parts of the body (metastatic cancer), can cause formation in this area. Possible causes of hilar lymph node enlargement (lymphadenopathy) are discussed below.
  • Pulmonary venous hypertension (increased pressure in the pulmonary veins): Pulmonary venous hypertension can occur due to conditions such as heart failure and heart valve problems such as mitral stenosis and mitral regurgitation.
  • Pulmonary arterial hypertension (PAH): This is an increase in pressure in the pulmonary arteries. PAH can occur as a primary disease (not secondary to another problem) or as a secondary problem, which in turn is more commonly caused by chronic obstructive pulmonary disease (COPD).
  • Increased pulmonary blood flow : Conditions such as cyanotic congenital heart disease (heart defects present at birth that cause a blue skin tone due to low oxygen content) can lead to increased pulmonary blood flow.

Hilar lymphadenopathy

Enlarged lymph nodes in the hilum can occur in both the right and left hilum (bilateral lymphadenopathy) or only on one side (asymmetric lymphadenopathy). The reasons may include:

  • Lung cancer: Lung cancer is the most common cause of uneven intrathoracic development in adults, both due to the presence of a tumor and the presence of affected lymph nodes.
  • Other cancers : metastatic breast cancer can cause hilar lymphadenopathy, both by the spread of the cancer to this area and by the involvement of the lymph nodes. Lymphoma and other tumors of the mediastinum can also cause an enlarged hilar lymph node.
  • Tuberculosis : Worldwide, tuberculosis is one of the most common causes of hilar lymphadenopathy in children.
  • Inflammation – Conditions such as sarcoidosis, amyloidosis , and silicosis can cause hilar lymphadenopathy. Sarcoidosis is the most common cause of bilateral enlargement of the intrathoracic lymph nodes, especially in young adults. Hilar lymph node enlargement in sarcoidosis is usually symmetrical, unlike other common causes. Drug reactions are also a relatively common cause of hilar lymphadenopathy.
  • Other infections : infections such as mycobacteria, viral infections such as infectious mononucleosis, beryllium disease, tularemia, histoplasmosis, and coccidioidomycosis can lead to swollen lymph nodes in this area. In the United States, histoplasmosis is common in the Ohio and Mississippi river valleys, while coccidioidomycosis is more common in the southwestern states.
  • Other causes : Castleman's disease is a condition characterized by abnormal lymphatic tissue. Heart failure can also cause hilar lymphadenopathy.

Get the word of drug information

There are a number of conditions that can make the door look abnormal in images, many of which are serious.

However, the first step is to ensure that any findings are not simply related to incorrect body posture when filming these films. With so many structures passing through this area, even slight rotation can cause an anomaly to appear when there is none.

Tumors, both primary and metastatic, are an all too common cause of intrathoracic neoplasms and lymphadenopathy. The most common causes include tuberculosis worldwide and conditions such as histoplasmosis, coccidioidomycosis, and sarcoidosis in the United States.

If your PCP detects an abnormality on your exam, more tests will be ordered. They will also ask you to take a complete medical history looking for other symptoms that suggest swelling, infection, or inflammation. In most cases, a biopsy is required to make an accurate diagnosis.

Frequently asked questions

  • The hilum is located closer to the back of each lung between the fifth and seventh thoracic vertebrae. This is where the bronchi, veins, arteries, and nerves enter and exit the lung.

  • The hilar lymph nodes are found at the entrance of the bronchus to the lung.

  • Court adenopathy is an enlarged lymph node at the gate. It can be caused by conditions such as tuberculosis, sarcoidosis, drug reactions, infections, or cancer.

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