What Are Enlarged Retroperitoneal Lymph Nodes?

Lymphoma Cancer Cell
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Lymph nodes are small bean-shaped structures located all over the body. They are part of the lymph system, a sort-of parallel network to the blood vessels of the circulatory system. Lymph nodes function like little immune system outposts, scattered along a system of canals that drain fluids from tissues in particular territories of the body.

When lymph nodes in a specific part of the body known anatomically as the retroperitoneum become enlarged, there are many potential causes, including the following:

  • Infections, such as tuberculosis
  • Inflammation from any number of causes, including diseases such as sarcoidosis
  • Cancer from a distant site in the body that metastasizes to the lymph nodes
  • Blood cancers that develop in the lymph nodes or spread to the lymph nodes
  • Other rare causes

There are always many different potential reasons for any lymph node to swell, and not all of them are cancerous. In fact, when a person sees a doctor for swollen lymph nodes, cancer is not usually the cause. Rather, a viral infection is more likely to blame—especially if the swollen lymph nodes are along the neck. However, there are some types of lymph node swellings that are less suggestive of benign conditions, such as a massive conglomeration of enlarged lymph nodes that appear stuck together in imaging studies.

Retroperitoneal Lymph Nodes May Enlarge in Various Diseases

Retroperitoneal lymph nodes are located in a place where they cannot generally be felt or noticed when they begin to swell, and so doctors may come to learn of their enlargement by way of an imaging study such as a CT scan of the abdomen and pelvis.

Sometimes retroperitoneal lymph nodes do become so involved with disease that they produce symptoms, as nearby structures may be affected. In some cases, symptoms might lead to an imaging study that detects the retroperitoneal lymph node enlargement. However, the cause of the swelling may not be readily apparent from the imaging scans, and a biopsy of the involved lymph nodes is often required.

In the case of people who have weakened immune systems, some of the possibilities for enlarged retroperitoneal lymph nodes are: infection with a kind of bacteria called Mycobacterium; lymphoma, a blood cancer that usually begins in the lymph nodes; and Kaposi's sarcoma, a cancer that develops from the cells that line lymph or blood vessels.

When enlarged lymph nodes are spotted in a particular part of the body such as the retroperitoneal area, there it is essentially a snapshot in time, so there are distinct possibilities in terms of the disease responsible.  The enlarged nodes might be the only the beginning phase of a disease that will eventually show lymph node enlargement in different sites of the body or progressive generalized lymphadenopathy syndrome.

When there are multiple sets of lymph nodes involved in the retroperitoneum and the scan also shows an enlarged liver and spleen, this can be more suggestive of lymphoma, however, there are other possibilities. Castleman disease is a rare disease that involves the lymph nodes. Other names include giant lymph node hyperplasia, and angiofollicular lymph node hyperplasia. Dr. Benjamin Castleman first described it in the 1950s.

Castleman disease is considered a lymphoproliferative disorder, meaning there is an overgrowth of cells of the lymph system. Though it is not cancer, it can be very similar to lymphoma, and some forms can develop into a lymphoma.

Where Is the Retroperitoneum and Why Does It Matter?

Gross anatomy determines the name of these lymph nodes. Retroperitoneal lymph nodes are lymph nodes located a specific compartment of the body, called the retroperitoneum. The retroperitoneum describes a part of the abdominal cavity—the part of the abdomen that is generally closer to your backbone than to your belly button, back behind the intestines.

Retroperitoneal lymph nodes are one of many lymph node groups found around the body, as shown in the following list:

  • Retroperitoneal lymph nodes - found in the retroperitoneum
  • Inguinal lymph nodes - found in the groin region
  • Axillary lymph nodes - found in the armpits
  • Mediastinal lymph nodes - found in the chest, near the heart

Lymph nodes can be named for any region of the body or for a specific organ. For example, there is a particular lymph node in the thorax that is near the aorta. That lymph node might generally be called a thoracic lymph node. Becoming more specific, if it is in the compartment near the heart, it would also be considered a mediastinal lymph node, or even more specifically, if it is located beside the aorta, a periaortic lymph node—all of which would be correct naming, but periaortic would be the most specific.

The peritoneum is a membrane that lines the cavity of the abdomen and also covers abdominal organs. Imagine it as a 'double bubble of plastic wrap' that get all twisted up in itself during development. Some organs are intraperitoneal, or within the peritoneum, while others are behind it, or retroperitoneal.

Retroperitoneal Organs

The reason for lymph node enlargement may sometimes relate to the organs that are near the enlarged nodes. Several organs are within the peritoneum and some are actually partially within and partially outside the peritoneum. Students may use the following memory device to learn which organs are retroperitoneal:

S: suprarenal or adrenal gland
A: aorta/inferior vena cava
D: duodenum (second and third part)

P: pancreas (except the tail of the pancreas)
U: ureters
C: colon (ascending and descending)
K: kidneys
E: esophagus
R: rectum

The organs followed by parentheses are only partially retroperitoneal. Sometimes a disease process 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, and masses in this area can block a ureter, causing urinary symptoms. Retroperitoneal lymphadenopathy often does not produce any symptoms, but extensive disease can lead to abdominal discomfort or blocked urine flow.

Retroperitoneal Lymph Nodes in Lymphoma

Lymphomas are a group of cancers of the lymph system. Lymphomas usually start in the lymph nodes, and retroperitoneal lymph nodes are affected in many lymphomas.

There are two main categories of lymphoma:
1) Hodgkin’s lymphoma, or HL-- and here is the link out to Hodgkin’s.
2) Non-Hodgkin’s lymphoma, or NHL which accounts for nearly 90 percent of all lymphomas, is comprised of far more types than Hodgkin's lymphoma.

Both HL and NHL may result in retroperitoneal lymph node involvement. While HL is more likely to spread in a defined pattern, from one lymph node group to the next, NHL may arise and come to involve different groups of lymph nodes, including retroperitoneal lymph nodes, at the time of presentation.

Retroperitoneal Lymph Nodes in Other Cancers

Other cancers can also metastasize to retroperitoneal lymph nodes. One such cancer is testicular cancer. Testicular cancer usually spreads in a predictable fashion through the retroperitoneal lymph nodes (RPLN), and in some instances, an operation called a retroperitoneal lymph node dissection (RPLND) is done. One possible complication of this surgery is retrograde ejaculation. If the surgeon cuts a nerve during the surgery, ejaculation still can occur, but the sperm end up in the bladder, and so infertility is a problem.

A Word From Verywell

When enlarged lymph nodes in the retroperitoneum are identified, the significance of this finding depends on all of the other information, including the medical history of the individual with the enlarged nodes. One important aspect of enlarged nodes in this particular location is that they are quite isolated from the rest of the body and are not as easily detected as lymph nodes in the neck, armpits or groin, for instance.

Sometimes lymph nodes are "borderline-enlarged" on imaging, meaning they are slightly larger than usual, but not necessarily a cause for concern. In these cases, there may be follow-up imaging performed and comparison to past studies to see if there has been enlargement in the interim.

Always talk to your health care team if you have questions about findings such as enlarged retroperitoneal lymph nodes or questions about the significance of these findings.

View Article Sources
  • Lymph Nodes. Lawrence M. Weiss. Cambridge University Press, Apr 28, 2008
  • Radiopaedia.org. Retroperitoneal organs (mnemonic).
  • Non-Hodgkin Lymphomas. James Armitage et al. Lippincott Williams & Wilkins, Aug 8, 2013.