What Are Enlarged Retroperitoneal Lymph Nodes?

Lymph nodes are small, bean-shaped structures located all over the body. They are part of the lymph system, a network of nodes, vessels, and ducts that function like immune outposts. The lymph system filters fluids from tissues to help defend against infection and minimize toxic exposure.

Retroperitoneal lymph nodes are located in the abdominal cavity. They can be found immediately behind the part of the intestine that is closer to your backbone than your belly button.

The swelling of the nodes is referred to as lymphadenopathy. Lymph nodes in the abdomen may become enlarged for a number of reasons, such as an infection like tuberculosis or as a result of a condition in a nearby organ.

Not all causes of enlarged retroperitoneal lymph nodes are cancerous. In fact, in most cases, cancer is the last concern on the list. Still, there are certain patterns of enlargement that require more extensive evaluation.

This article discusses the symptoms, causes, diagnosis, and treatment of enlarged lymph nodes.

Symptoms

Unlike other types of lymph nodes, retroperitoneal lymph nodes generally cannot be felt or seen when enlarged. Because of this, doctors will often only discover an enlargement after an imaging scan of the abdomen and pelvis, such as a computed tomography (CT).

Some conditions that cause enlarged retroperitoneal lymph nodes may have associated symptoms. Specifically, people who have enlarged retroperitoneal lymph nodes related to lymphoma may also experience:

• Abdominal pain and bloating
• Fatigue
• Fever
• Anemia
  

When retroperitoneal lymph nodes are enlarged due to metastatic cancer, symptoms might include:

• Abdominal pain and bloating
• Pain that radiates through the lower back
• Jaundice (yellowing of the skin and eyes)
• Poor appetite

Causes

Causes of enlarged retroperitoneal lymph nodes can be primary or secondary. Primary causes arise in the lymph nodes themselves. Secondary causes are related to other conditions in nearby organs.

Primary Causes

Oftentimes, lymph nodes in the abdomen become enlarged as a result of an infection. If the infection is confined to the abdomen, the enlarged lymph nodes will be found only in a small area. If it's a systemic infection that involves the whole body, the enlarged lymph nodes will be more spread out.

Some of the causes of swollen retroperitoneal lymph nodes include:

• Infections like tuberculosis
• Inflammatory conditions such as sarcoidosis
• Cancers that spread (metastasize) to the lymph nodes
• Blood cancers that develop in the lymph nodes or spread to the lymph nodes
• Rare, noncancerous conditions like Castleman disease, which cause the overgrowth of lymph nodes
  

Secondary Causes

More often than not, the cause of swollen retroperitoneal lymph nodes will be secondary. This means they happen because of a disease or disorder affecting an organ within or near the retroperitoneum. These include organs such as:

• Adrenal glands
• Ascending or descending colon and duodenum
• Esophagus
• Kidneys and ureters
• Pancreas

Sometimes a disease that affects one of these organs will also affect the associated lymph nodes and vice versa.

For instance, the ureters carry urine from the kidney to the bladder. Masses in this area can block a ureter, triggering inflammation and the production of inflammatory cytokines, which are molecules that play a role in the immune response. When this happens, retroperitoneal lymphadenopathy will almost always occur.

Cancers

Cancer is clearly the most concerning cause of retroperitoneal lymphadenopathy. Two of the most common malignancies associated with this are lymphoma and testicular cancer.

Lymphoma

Lymphomas are a group of cancers that are considered lymphoproliferative. This means they cause excessive production of white blood cells called lymphocytes. Lymphomas usually start in the lymph nodes, typically the retroperitoneal lymph nodes. There are two main categories of lymphoma:

• Hodgkin lymphoma (HL), which primarily affects the lymph nodes
• Non-Hodgkin lymphoma (NHL), which affects the lymph nodes and other organs
  

Testicular Cancer

Cancers can often spread from a primary tumor to retroperitoneal lymph nodes. One such cancer is testicular cancer.

Diagnosis

Swollen lymph nodes by themselves can't tell much about the underlying illness. Still, there are some red flags healthcare providers will look for.

Certain patterns of enlargement are worrisome. For example, a large mass of lymph nodes that appears stuck together on an imaging scan may be a sign of metastatic cancer.

In instances like these, your healthcare provider may recommend additional tests such as:

• A biopsy, which is a procedure where a sample of tissue is removed for evaluation
• A positron emission tomography (PET) scan, which is able to detect metastatic cancer better than other imaging technologies

Metastatic testicular cancer usually spreads in a predictable fashion. It tends to move progressively through the lymphatic system and typically establishes in the nodes of retroperitoneum.

A CT scan may also provide other indications of the potential cause. For example, If both the liver and spleen are enlarged along with the retroperitoneal lymph nodes, this may be a sign of lymphoma.

Treatment

Treatment of enlarged lymph nodes in the abdomen usually involves treating the underlying cause. For example, tuberculosis is typically treated with a combination of antibiotics.

Retroperitoneal lymph nodes can be removed if the cause of the enlargement is metastatic cancer. This is done during an operation called a retroperitoneal lymph node dissection (RPLND).

During RPLND, the retroperitoneal lymph nodes are removed through an incision in the abdomen. The procedure is done under general anesthesia, which means you will be in a sleep-like state. It usually takes 3.5 to 5 hours. 

Summary

Retroperitoneal lymph nodes are located in the abdomen. They may become enlarged because of primary or secondary causes. Primary causes include things like infections or cancers that develop in the lymph nodes. Secondary causes include conditions affecting nearby organs like the kidneys or pancreas. 

To treat enlarged retroperitoneal lymph nodes, healthcare providers typically treat the underlying cause. 

Sometimes enlarged retroperitoneal lymph nodes happen when cancer spreads from another part of the body. This is a less common cause of this condition.

A Word From Verywell

The significance of enlarged lymph nodes in the retroperitoneum depends on many other factors, such as medical history and the pattern of enlargement.

One important aspect of enlarged nodes in this particular location is that they are quite isolated from the rest of the body. This means they are not as easily detected as lymph nodes in other places such as the neck, armpits or groin.

Sometimes lymph nodes are "borderline-enlarged" on imaging. This means they are slightly larger than usual, but not necessarily a cause for concern. In this case, you may need follow-up imaging and comparison to past studies to see if your lymph nodes are becoming larger over time.

Always talk to your healthcare team if you have questions about the significance of enlarged retroperitoneal lymph nodes.