Retroperitoneal lymphadenitis is caused by bacterial, viral, or subcutaneous node infections, leading to acute retroperitoneal lymphadenitis, or chronic or subcutaneous node-related retroperitoneal lymphadenitis.

bubble_chart Pathogenesis

The retroperitoneal space is a potential gap bounded superiorly by the diaphragm and inferiorly by the pelvic diaphragm. Its anterior boundary mainly includes the parietal peritoneum of the posterior abdominal wall, the bare area of the right liver, parts of the duodenum, ascending colon, and rectum. Posteriorly, it is bordered by the vertebral bodies, psoas major, quadratus lumborum muscles, and the origins of the transversus abdominis from the lumbar fascia, as well as the sacrum, psoas major, and piriformis muscles below the iliac crest. Laterally, it is bounded by the iliacus and obturator muscles. The primary organs within this space are the kidneys, ureters, adrenal glands, and pancreas, along with major blood vessels, lymphatic tissues, and nerves, all embedded in abundant adipose and loose connective tissue.

Some structures are easily exposed extraperitoneally, such as the adrenal glands, kidneys, ureters, lumbar sympathetic chain, splenic arteries and veins, renal arteries and veins, abdominal aorta, inferior vena cava, common iliac arteries and veins, internal iliac arteries and veins, pancreas, and inguinal canal.

There are many different theories, generally including:

1. Bacterial infection: often originating from gastrointestinal infections or systemic bloodstream infections from other organs.

2. Viral infection: commonly caused by upper respiratory infections or mumps.

3. Subcutaneous node infection: retroperitoneal lymphadenitis with subcutaneous nodes is relatively common, which may be primary in the retroperitoneal lymph nodes or secondary to subcutaneous node diseases of the gastrointestinal tract, abdominal cavity, or lungs.

1. Acute retroperitoneal lymphadenitis

is mainly characterized by high fever and shivering, accompanied by abdominal pain, abdominal distension and fullness, back pain, nausea, vomiting, etc. The body temperature can reach 39–40°C, presenting as remittent or continuous fever. Abdominal tenderness and rebound tenderness may be observed upon examination, but muscle rigidity is not obvious. In severe cases, signs of intestinal paralysis, back percussion pain, and elevated white blood cell counts may occur.

2. Chronic or tuberculous retroperitoneal lymphadenitis

Tuberculosis bacteria can invade the retroperitoneal lymph nodes, either as part of the primary complex or as a result of widespread tuberculosis dissemination. Affected lymph nodes may be treated asymptomatically and eventually calcify. Some lymph nodes may enlarge, undergo caseous necrosis, or even form abscesses. The onset of this disease is often insidious, with vague or even absent symptoms. The main symptoms include persistent or paroxysmal dull pain or distending pain in the abdomen, accompanied by low-grade fever, nausea, vomiting, abdominal distension and fullness, and loss of appetite. The abdominal pain may occur intermittently and often responds poorly to treatments such as antibiotics, antituberculosis drugs, or antispasmodics. Some reports have described compression or displacement of the proximal ureter and kidney, pyloric obstruction, gastric wall rigidity, notching or stenosis of the duodenum, dilation of the duodenal loop, and transverse colon displacement. Rare manifestations include leg swelling, chylous ascites, portal hypertension, biliary obstruction, and fistula formation. Upon examination, a mass or localized fullness may be palpable in the abdomen, with deep tenderness but no abdominal muscle rigidity, and active borborygmi.

The diagnosis of this disease is often difficult to confirm before surgery. Common abnormal findings include an elevated erythrocyte sedimentation rate, the presence of subcutaneous nodule lesions (old or active) in other areas, abdominal masses, and low-grade fever. X-rays, B-ultrasound, CT scans, subcutaneous nodule antibody tests, or subcutaneous nodule bacillus tests can aid in diagnosis. The final confirmation depends on a biopsy of the affected area.

bubble_chart Treatment Measures

The primary approach is to administer antibacterial drugs or Chinese medicinals based on the nature of the infection. For subcutaneous nodules, standard anti-subcutaneous nodule treatment should be provided, but the course of treatment requires 1 to 2 years. Larger abscesses require drainage. For more localized masses or cases where adjacent organs are compressed and non-surgical treatments are ineffective, surgical resection may be considered.

bubble_chart Differentiation

It should be differentiated from diseases such as lymphoma, pancreatic cancer, retroperitoneal or mesenteric tumors, sarcoidosis, appendicitis, adnexitis, malignant tumors, benign lymphoid hyperplasia, and infectious mononucleosis.