Mesenteric Adenitis

Definition

• Inflammation or infection of mesenteric lymph nodes in the abdomen

• Often follows a viral URTI or tonsillitis; bacterial causes such as Yersinia enterocolitica may be involved

• Common in children and adolescents, though it can occur at any age

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Presentation

• Right lower quadrant pain that is less localised than in appendicitis and may shift in location

• Mild fever, nausea, and anorexia that are generally less severe than with appendicitis

• May be associated with cervical lymphadenopathy or pharyngitis following a recent infection

• Typically self-limiting with resolution in 3–5 days without residual effects

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Differential Diagnosis

• Appendicitis

  • More localized RLQ pain with rebound tenderness and peritonitis

  • Typically lacks a preceding URTI

• Gastroenteritis

  • Diffuse abdominal pain accompanied by diarrhoea and vomiting

• Intussusception

  • Colicky pain with red currant jelly stools and a palpable abdominal mass

• Pelvic inflammatory disease (in females)

  • Lower abdominal pain with associated vaginal discharge

• Urinary tract infection

  • Fever, dysuria, and malodorous urine

• Other causes such as inflammatory bowel disease or mesenteric adenitis secondary to Yersinia infection

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Investigations

• Abdominal ultrasound

  • Visualises enlarged mesenteric lymph nodes and helps exclude appendicitis

• Blood tests

  • Full blood count may reveal mild leucocytosis; CRP can be mildly elevated

• Additional imaging (CT scan) is rarely required unless the diagnosis remains uncertain

• Urinalysis

  • To exclude urinary tract infection as a cause of abdominal pain

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Management

• Symptomatic treatment with rest and adequate hydration

• Provide analgesia and antipyretics such as paracetamol or ibuprofen

• Avoid antibiotics unless there is clear evidence of a bacterial infection

• Observation and follow-up to ensure improvement; re-evaluate if symptoms persist or worsen beyond 3–5 days

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Differentiating from Appendicitis

• Mesenteric adenitis presents with more diffuse, less localized RLQ pain and milder abdominal rigidity

• Often preceded by an upper respiratory tract infection or pharyngitis

• Appendicitis typically shows localized tenderness, rebound, and signs of peritonitis requiring urgent surgical review

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Notes

• Diagnosis is primarily clinical and made by exclusion once appendicitis and other serious causes are ruled out

• Educate caregivers to monitor for worsening symptoms such as persistent fever, increasing pain, or vomiting

• Follow-up is essential to confirm resolution and to manage any complications promptly

• Mesenteric adenitis is self-limiting and usually resolves without long-term sequelae