What is mesenteric lymphadenitis in patients of any age, particularly in children and young adults with a history of gastrointestinal infections or inflammatory bowel disease?

What is Mesenteric Lymphadenitis

Mesenteric lymphadenitis is a self-limiting inflammatory condition affecting the mesenteric lymph nodes that typically occurs in children, adolescents, and young adults, presenting with abdominal pain that mimics acute appendicitis or intussusception. 1

Definition and Pathophysiology

Mesenteric lymphadenitis (also called acute nonspecific or primary mesenteric lymphadenitis) represents inflammation of the lymph nodes within the mesentery of the intestine. 1 The condition is characterized by enlargement of mesenteric lymph nodes without an identifiable underlying inflammatory process in the bowel itself. 1

Clinical Presentation

The hallmark symptom is abdominal pain, which occurs in approximately 50% of patients and may be the sole presenting complaint in about 26% of cases. 2 When compared to acute appendicitis, patients with mesenteric lymphadenitis demonstrate several distinguishing features:

• Longer duration of symptoms before seeking care (2.4 days versus 1.4 days for appendicitis) 3
• Multiple emergency department visits (1.3 versus 1.05 visits) 3
• Less frequent migration of pain (7% versus 28% in appendicitis) 3
• Less vomiting (34% versus 62% in appendicitis) 3
• Fewer classic peritoneal signs (20% versus 72% in appendicitis) 3

Additional symptoms may include vomiting and fever when present alongside abdominal pain. 2

Diagnostic Criteria

Ultrasonography is the mainstay of diagnosis, revealing 3 or more mesenteric lymph nodes with a short-axis diameter of 8 mm or more without any identifiable underlying inflammatory process. 1 Some sources use a threshold of 5 mm or more for defining enlarged nodes. 2

Laboratory Findings

Laboratory parameters show characteristic differences from acute appendicitis:

• Lower white blood cell counts (10.16 × 10³/dL versus 15.8 × 10³/dL in appendicitis) 3
• Lymphocyte predominance (24.6% versus 13% in appendicitis) 3
• Lower C-reactive protein levels (0.48 mg/dL versus 1.6 mg/dL in appendicitis) 3

Important caveat: White blood count and C-reactive protein have limited usefulness in distinguishing between patients with and without mesenteric lymphadenitis. 1 Elevated inflammatory parameters are present in only about 33% of patients. 2

Imaging Characteristics

Ultrasound typically demonstrates:

• Numerous enlarged lymph nodes in 51% of cases 2
• Long axis reaching at least 10 mm in 67% of patients 2
• Lymph node conglomerates in 7% of cases, which may be associated with various diagnoses including acute diarrhea, ulcerative colitis, or celiac disease 2
• Tendency toward intussusception in approximately 4% of children, particularly those with acute infections and high inflammatory parameters 2

Critical pitfall: Enlarged abdominal lymph nodes exceeding 10 mm are frequently encountered in asymptomatic children (64% prevalence) and should not always be considered abnormal. 4 Only lymph nodes of 10 mm or larger show statistically significant differences between symptomatic and asymptomatic children. 4

Etiology

In approximately 21% of cases, primary mesenteric lymphadenitis is diagnosed with no identifiable underlying cause. 2 When a cause is identified, the most common etiologies include:

• Acute diarrhea (16% of cases) 2
• Respiratory tract infections (15% of cases) 2
• Parasitic infections: Giardiasis (7%), toxoplasmosis (2.3%) 2
• Viral infections: Cytomegalovirus (3%) 2
• Inflammatory bowel disease: Gastritis and colitis (9%) 2

The distribution of lymph nodes may indicate the nature of the underlying disease process. 5

Management

Once the diagnosis is established, supportive care including hydration and pain medication is advised. 1 The condition is self-limiting, and affected patients recover completely without residuals within 2-4 weeks. 1

Crucial to management is reassuring patients and families by explaining the benign nature of the condition and the expected complete recovery. 1

Age-Related Considerations

There is a tendency for increased occurrence of enlarged abdominal lymph nodes with age, peaking at 10 years, with a decrease thereafter. 4 The condition typically affects children, adolescents, and young adults. 1

No significant difference exists between small and large lymph node presentations, suggesting that lymph node enlargement itself is a non-specific finding. 3 This emphasizes the importance of clinical context rather than relying solely on imaging measurements.