Mediastinal Lymphadenopathy

Mediastinal lymph nodes are lymph nodes located in the mediastinum. The mediastinum is the area located between the lungs which contains the heart, esophagus, trachea, cardiac nerves, thymus gland, and lymph nodes of the central chest.

The enlargement of lymph nodes is referred to as lymphadenopathy. Mediastinal lymphadenopathy generally suggests a problem related to lungs, whether benign or malignant.

Causes

There can be many different reasons why mediastinal lymph nodes become enlarged. The most common causes include:

• Acute lymphoblastic leukemia
• Anthracosis ("miner's lung")
• Chronic obstructive pulmonary disease (COPD)
• Coccidioidomycosis
• Cystic fibrosis
• Esophageal cancer
• Histoplasmosis
• Lung cancer
• Lymphoma
• Sarcoidosis
• Tuberculosis

Diagnosis

If the cause of the mediastinal lymphadenopathy is uncertain, your doctor may order a procedure known as mediastinoscopy with biopsy. This 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. The results are usually ready in five to seven days.

A less invasive procedure is known as fine needle aspiration (FNA) in which a long needle is inserted through the chest cavity into a lymph node to extract cells.

Investigating Cancer

Lymph nodes are small structures located in clusters throughout the body through which toxins and pathogens can be filtered. Mediastinal lymph nodes are typically the first ones that cancer cells from the lungs will trap, providing doctors the means to know if cancer is spreading.

When the mediastinal lymph nodes are enlarged due to a malignancy, lung cancer and lymphoma are the two most likely causes.

However, in some cases, the enlargement may not be related to a primary cancer of the lungs but rather to metastatic cancer that has spread from another part of the body to the lungs. In this instance, the lung malignancy would be considered secondary cancer.

The location and number of affected lymph nodes are also central to the staging of cancer, a classification system that determines how advanced malignancy is, which treatments should be administered, and what outcomes can be expected.

Significance in Lymphoma

Lymphoma, a cancer of a type of white blood cells called lymphocytes, can be categorized as either Hodgkin lymphoma or non-Hodgkin lymphoma. Mediastinal lymphadenopathy is one of the ways to differentiate two diseases.

While chest imaging can identify suspicious-looking lymph nodes, a definitive diagnosis can only be made by biopsy.