Mediastinal lymphadenopathy is the swelling of lymph nodes in the chest, specifically the mediastinum (the area between the lungs containing the heart, trachea, and esophagus). It is a sign of an underlying medical condition.

Some of the conditions that may cause mediastinal lymphadenopathy include an infection such as tuberculosis, an inflammatory condition like COPD, certain autoimmune diseases, and cancers such as lymphoma and lung cancer. Treatment typically involves treating the underlying condition.

This article discusses some of the causes of mediastinal lymphadenopathy and how the underlying conditions are diagnosed and treated.

Mediastinal Lymphadenopathy Causes

Lymph nodes are small structures located in clusters throughout the body. They filter toxins and pathogens (infectious organisms).

Mediastinal lymph nodes are lymph nodes located in the mediastinum. The mediastinum is the area located between the lungs that contains the heart, esophagus, trachea, cardiac nerves, thymus gland, and lymph nodes of the central chest. Conditions that cause inflammation in the chest area can cause enlargement of the lymph nodes of the chest.

Mediastinal lymphadenopathy does not always mean cancer, although cancer is a common cause. Lymph nodes can also become enlarged due to infections and inflammatory diseases.

Cancer

When the mediastinal lymph nodes are enlarged due to a malignancy, lung cancer and lymphoma are the two most likely causes. Enlarged lymph nodes can also be a symptom of acute lymphoblastic leukemia (ALL).

It is also possible for enlarged lymph nodes to occur as a result of metastases (spread) of other cancers, such as:

• Esophageal cancer
• Prostatic cancer
• Gastrointestinal cancer
  

Cancer cells from the lungs typically travel to the mediastinal lymph nodes first. This is why the mediastinal lymph nodes can be examined to determine whether cancer is spreading.

In some cases, mediastinal lymph node enlargement occurs due to secondary lung cancer, when metastatic cancer spreads from another part of the body to the lungs and then to the lymph nodes.

The location and number of lymph nodes involved is an important aspect of cancer staging. This classification system defines how advanced the cancer is, which helps determine treatment and probable outcome.

Infection

Worldwide, mediastinal lymphadenopathy is primarily associated with tuberculosis (TB). TB has a high rate of infection (10 million per year). It is more common in Africa, Eastern Europe, and Asia than it is in the United States.

Other fungal, bacterial, or viral infections can also cause mediastinal lymphadenopathy. Examples include:

• Coccidioidomycosis
• Histoplasmosis
• Severe COVID-19 infection
  

Autoimmune Diseases

An autoimmune condition occurs when your immune system mistakenly attacks your body's own tissues. Certain autoimmune conditions can cause enlarged mediastinal lymph nodes, including:

• Sarcoidosis
  
• Lupus
  
• Sjögren's syndrome
• Rheumatoid arthritis

Other Inflammatory Conditions

In the United States, chronic obstructive pulmonary disease (COPD) is one of the most common causes of mediastinal lymphadenopathy. Other inflammatory conditions that can cause enlarged mediastinal lymph nodes include:

• Anthracosis ("miner's lung")
• Hypersensitivity pneumonitis
  
• Cystic fibrosis
  

Symptoms

Because mediastinal lymph nodes are inside the chest cavity, they are usually only observed on imaging tests. With that said, enlarged lymph nodes can sometimes compress structures within the chest and cause symptoms such as:

• Coughing
• Shortness of breath
• Wheezing
• Problems swallowing

Diagnosis

Generally, mediastinal lymphadenopathy is diagnosed with imaging tests, such as chest ultrasound, chest computed tomography (CT), positron emission tomography (PET), or chest MRI. These tests can provide a non-invasive assessment of the number and size of the enlarged lymph nodes. Sometimes the cause of lymph node enlargement might already be known due to the underlying medical conditions (such as TB or ALL).

If the cause of the mediastinal lymphadenopathy is uncertain, your healthcare provider may order a biopsy so the tissue can be examined microscopically and the cause can be identified.

• Mediastinoscopy involves a small surgical cut made just above the sternum or breastbone. A fiber-optic instrument called a mediastinoscope is then inserted through the incision and passed into the mid-part of the chest to obtain a sample of one or several lymph nodes. The procedure is performed in a hospital under general anesthesia.
• Fine needle aspiration (FNA) is a less invasive method of obtaining a biopsy sample. During this procedure, a sample of cells is collected using endobronchial ultrasound guidance, in which a tube is inserted into the mouth and advanced down into the lungs.

The biopsy results are usually ready in five to seven days.

How Is Mediastinal Lymphadenopathy Treated?

Mediastinal lymphadenopathy may not be treated directly since it is ultimately the result of an underlying disease or infection. Treating the underlying cause will usually resolve the condition. However, with diseases like non-small cell lung cancer, the dissection (removal) of mediastinal lymph nodes is linked to improved survival times.

Summary

Mediastinal lymphadenopathy is when the lymph nodes in the chest become enlarged. A number of conditions can cause this, including infections, inflammatory diseases, autoimmune conditions, and certain cancers.

Mediastinal lymphadenopathy doesn't usually cause symptoms. It is typically diagnosed with an imaging test such as a CT scan or an MRI. If cancer is suspected, your healthcare provider may also order a biopsy.

Enlarged mediastinal lymph nodes are treated by treating the underlying cause. For some types of cancer, the lymph nodes may be removed surgically.

By Indranil Mallick, MD
 Indranil Mallick, MD, DNB, is a radiation oncologist with a special interest in lymphoma.