Mesenteric adenitis (MA) is characterized by inflammation of the lymph nodes located in the mesentery, the tissue that attaches the intestine to the back of the abdominal wall. These lymph nodes are part of the body’s immune system and swell when fighting an infection. MA is a frequent cause of abdominal pain, particularly in children and young adults. This temporary swelling causes discomfort and can sometimes be mistaken for other serious conditions.
Primary Infectious Triggers
Most cases of Mesenteric Adenitis (MA) result from the body’s immune response to an infection, typically gastrointestinal or respiratory. The infection causes a localized inflammatory reaction, leading to the enlargement of lymph nodes closest to the infection site.
One of the most specific bacterial causes is Yersinia enterocolitica, a gram-negative bacterium often acquired through contaminated food like undercooked pork or unpasteurized milk. After ingestion, the bacteria colonize the gastrointestinal tract and invade the epithelial lining of the small intestine. They then travel through the lymphatic vessels to the regional mesenteric lymph nodes, where they multiply and trigger the inflammatory swelling that defines MA. Other bacterial culprits include Salmonella, certain strains of E. coli, and Streptococci.
Viral infections are a frequent cause of MA, often preceding the onset of abdominal pain. Viral gastroenteritis, commonly referred to as “stomach flu,” causes inflammation throughout the digestive tract. This widespread inflammation activates the regional lymph nodes to filter and fight the pathogen, leading to swelling.
MA is often associated with a recent or concurrent upper respiratory tract infection, such as a common cold or sore throat. While the infection site is not the abdomen, the systemic immune activation and movement of inflammatory agents can still lead to secondary swelling of the mesenteric lymph nodes. This swelling is a local manifestation of a broader systemic immune response.
Secondary and Non-Infectious Associations
While infectious agents account for most cases, MA can also be associated with other systemic processes. Certain chronic inflammatory conditions, such as Crohn’s disease, a form of Inflammatory Bowel Disease (IBD), can present with or mimic MA. In these instances, the underlying chronic inflammation in the intestinal wall leads to persistent activation and enlargement of the surrounding mesenteric lymph nodes.
Less common, non-infectious causes of lymph node enlargement include conditions like lymphoma, a cancer of the lymphatic system. These secondary associations are differentiated from primary infectious MA through diagnostic imaging and blood work, as they often involve more pervasive or prolonged lymphadenopathy.
Identifying the Key Symptoms
The main clinical manifestation of MA is abdominal pain, which varies in location and intensity. The pain is frequently localized to the lower right quadrant of the abdomen, known as the right iliac fossa. This specific location often causes MA to be mistaken for acute appendicitis, as the inflamed lymph nodes are situated near the appendix.
Accompanying the abdominal discomfort is often a fever, reflecting the underlying infectious or inflammatory process. Patients experience other gastrointestinal symptoms, including nausea, vomiting, and a change in bowel habits, sometimes presenting as diarrhea. A general feeling of being unwell, or malaise, along with reduced appetite, is also reported.
The condition can be classified as acute, where symptoms appear suddenly and resolve quickly, or chronic, where symptoms persist for several weeks or recur. The presentation of MA as “pseudoappendicitis” is common in older children and adolescents who are susceptible to localized inflammation near the terminal ileum.
Confirming the Condition and Prognosis
Diagnosing Mesenteric Adenitis requires careful evaluation to distinguish it from more urgent conditions like appendicitis. A physical examination checks for localized tenderness, and blood tests may be used to look for signs of a bacterial or viral infection.
The most definitive way to confirm the condition is through medical imaging, typically an abdominal ultrasound or a CT scan. These scans allow physicians to visualize enlarged lymph nodes, defined as measuring 8 millimeters or more in their short-axis diameter. Imaging is crucial for ruling out other causes of pain, such as an inflamed appendix.
MA is a self-limiting condition, meaning it resolves on its own without specific medical intervention. The prognosis is positive, with symptoms often improving within a few days and clearing up completely within two to four weeks. Treatment focuses on supportive care, including adequate hydration, pain relief medications, and rest until symptoms subside.