Lymph nodes



Lymph node

Lymph nodes are small, bean-shaped structures that are part of the body’s lymphatic system. The lymphatic system is a network of tissues and organs, including lymph nodes, that help the body fight infections and other diseases. Each lymph node acts like a filter, trapping germs, cellular debris, foreign particles, and cancer cells.

What do lymph nodes do?

Lymph nodes play an essential role in the body’s immune system. They filter lymph fluid containing waste products, bacteria, and other harmful substances. The lymph nodes also store white blood cells, which help the body identify and fight infections. When there is an infection, inflammation, or cancer, the lymph nodes may swell as they work to filter out harmful substances and produce more white blood cells.

Where are lymph nodes found in the body?

Lymph nodes are found throughout the body, often in clusters. Some of the most well-known locations include the neck, armpits, chest, abdomen, and groin. There are hundreds of lymph nodes in the body, and they are usually located near major blood vessels and in areas where infections are most likely to enter the body.

What is the structure of a normal lymph node and what types of cells are typically found in the lymph node?

A normal lymph node has a distinct structure with an outer layer called the capsule and an internal tissue network. The inside of the lymph node is divided into two main areas: the cortex and the medulla. The cortex contains groups of cells called follicles, which are mainly made up of B cells. B cells are a type of white blood cell that helps produce antibodies to fight infections. The medulla contains T cells, another type of white blood cell that directly attacks infected or abnormal cells. The lymph node also has spaces called sinuses that allow lymph fluid to flow through the node, carrying cells and waste products.

How big is a normal lymph node?

The size of a normal lymph node can vary depending on its location in the body. Generally, most normal lymph nodes are small, ranging from 1 to 2 centimeters (cm) in diameter. Lymph nodes in the neck or groin areas may be slightly larger, while those in the chest or abdomen are often smaller. A lymph node larger than 2 cm, especially if it continues to grow or is firm and fixed in place, may indicate an underlying condition that requires further examination. In imaging studies, such as MRI or CT scans, the term “lymphadenopathy” is often used to describe enlarged lymph nodes.

What types of conditions affect lymph nodes?

Lymph nodes can be affected by a variety of conditions, including:

  • Infections – The lymph nodes may swell and become tender when the body fights an infection. This is often referred to as swollen or “reactive” lymph nodes and is a typical response to conditions like a cold, flu, or throat infection.
  • Autoimmune diseases – Conditions like rheumatoid arthritis and lupus can cause lymph nodes to swell as part of an abnormal immune system response.
  • Cancers – Lymph nodes can be affected by cancers such as lymphoma (cancer that starts in the lymphatic system) or metastatic cancers (cancers that have spread from other parts of the body).
  • Inflammatory conditions – Non-infectious inflammation, such as from a condition called sarcoidosis, can cause lymph nodes to enlarge.

What does it mean if a lymph node is described as reactive?

A reactive lymph node means that it is responding to an infection, inflammation, or other stimulus. In this situation, the lymph node enlarges and may contain more white blood cells than usual to help fight the infection or inflammation. Reactive lymph nodes are not cancerous and usually return to their normal size once the underlying cause is resolved.

What types of cancer start in a lymph node?

The most common type of cancer that starts in a lymph node is called lymphoma. Lymphoma is a cancer of the lymphatic system, which includes lymph nodes, the spleen, and other lymphoid tissues. Lymphomas are divided into two main types: Hodgkin lymphoma and non-Hodgkin lymphoma.

  • Hodgkin lymphoma – This type of lymphoma usually starts in the lymph nodes in the neck or chest. It is characterized by a specific type of abnormal cell called the Reed-Sternberg cell.
  • Non-Hodgkin lymphoma – This is a diverse group of lymphomas involving any lymph node in the body. There are many subtypes, with some of the most common including diffuse large B-cell lymphoma and follicular lymphoma. Non-Hodgkin lymphoma can vary in how quickly it grows and spreads.

Lymphomas can affect lymph nodes in a localized area or spread to multiple lymph nodes throughout the body.

What types of cancers commonly spread to lymph nodes?

Carcinomas and melanoma are types of cancers that commonly spread to lymph nodes.

  • Carcinoma – This is a cancer that starts in the cells lining organs, such as the skin, lungs, breasts, and gastrointestinal tract. Carcinomas often spread to nearby lymph nodes as they grow, which can be an important step in determining the stage of the cancer. For example, breast cancer often spreads to the lymph nodes in the axilla (armpit), while lung cancer may spread to lymph nodes in the chest.
  • Melanoma – This is a type of cancer that typically starts in the skin and frequently spreads to nearby lymph nodes. When melanoma spreads, it often travels through the lymphatic system to the closest lymph node group, the sentinel lymph nodes. The involvement of lymph nodes in melanoma is a key factor in deciding treatment options and predicting the outcome.

In contrast, sarcoma, a cancer that begins in tissues like muscles, bones, fat, and nerves, is much less likely to spread to lymph nodes. Instead, sarcomas are more likely to spread to other areas, such as the lungs.

What is a lymph node metastasis?

Lymph node metastasis occurs when cancer cells spread from their original site to a nearby lymph node. This process is a common way for some cancers to spread, especially breast, lung, and colon cancers. When cancer cells are found in a lymph node, it indicates that the cancer has started to spread beyond its original location. The presence of metastasis in lymph nodes changes the cancer stage and guides treatment decisions.

Why do pathologists examine lymph nodes?

Pathologists examine lymph nodes to help diagnose conditions and guide treatment. For example, examining lymph nodes in cancer can provide information about whether the cancer has spread and how advanced it may be. The pathologist looks at the lymph nodes under a microscope to check for the presence of cancer cells, infections, or other abnormalities. The findings can help doctors determine the best treatment plan and predict the likely outcome for the patient.

A+ A A-

Did you find this article helpful?