Makindo Medical Notes Comprehensive Medical Encyclopedia | Education for Healthcare Professionals

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Mesenteric adenitis

Mesenteric adenitis (or mesenteric lymphadenitis) refers to inflammation of the mesenteric lymph nodes, usually in the right lower quadrant of the abdomen. It is a common mimic of acute appendicitis, particularly in children and adolescents, and is often associated with a preceding viral or bacterial infection. Most cases are benign and self-limiting, but recognition is important to avoid unnecessary surgery.

🔬 Etiology & Pathophysiology

🦠 Infectious: Most common cause. Viral (e.g. adenovirus, enterovirus) or bacterial (e.g. Yersinia enterocolitica, Campylobacter, Salmonella).
🌡️ Post-infectious: Following upper respiratory tract or gastroenteric infections.
⚠️ Secondary causes: Can occur with inflammatory bowel disease (Crohn’s, ulcerative colitis), tuberculosis, lymphoma, or other intra-abdominal infections.
Pathology: Hyperplasia and inflammation of mesenteric lymph nodes, often in the ileocaecal region.

🧩 Clinical Features

👶 Typically affects children and adolescents, but adults may be affected.
🤕 Abdominal pain – often colicky, centred in right lower quadrant, mimicking appendicitis.
🌡️ Fever – usually low-grade, may follow recent viral illness.
🚽 Associated symptoms – nausea, vomiting, diarrhoea, anorexia.
🫁 Recent sore throat, cough, or other respiratory infection often reported.
🩺 Examination – localised RLQ tenderness, but usually less peritoneal irritation than appendicitis.

📊 Differentials

Acute appendicitis (most important to exclude).
Intussusception.
Inflammatory bowel disease (esp. Crohn’s).
Gastroenteritis.
Meckel’s diverticulitis.
Ovarian/testicular torsion in adolescents.

🧪 Investigations

Bloods: Mild leucocytosis and CRP elevation; often less marked than appendicitis.
Ultrasound: First-line imaging in children. Shows enlarged, clustered lymph nodes (≥5 mm short axis), absence of appendiceal thickening.
CT scan (adults): Enlarged mesenteric nodes with a normal appendix, excludes other causes.
Stool cultures: If enteric bacterial infection suspected (e.g. Yersinia).

💊 Management

✅ Supportive care: Most cases are self-limiting within 1–4 weeks.
💊 Analgesia & antipyretics: Paracetamol/NSAIDs for pain and fever.
💧 Hydration: Encourage oral fluids; IV fluids if unwell.
🦠 Antibiotics: Not routinely required unless bacterial infection confirmed or immunocompromised host.
🏥 Hospital admission: Consider if diagnosis uncertain, severe pain, systemic features, or complications.

⚠️ Complications

Rare, but may include:
- Misdiagnosis leading to unnecessary appendectomy.
- Chronic/recurrent pain syndromes in a minority of patients.
- Underlying pathology (e.g. IBD, lymphoma) if persistent.

💡 Teaching Pearls

🔍 Always consider mesenteric adenitis in a child with RLQ pain and a recent viral illness. 🧪 Ultrasound is the investigation of choice – it reduces negative appendectomy rates. 📉 Most cases resolve without treatment – reassurance and follow-up are key. ⚠️ Persistent or atypical cases should prompt evaluation for IBD, TB, or malignancy.

PLEASE NOTE LEGAL ADVICE: The contents are under continuing development and improvements and may contain errors of omission or fact. Feedback vital and always welcome at drokane at gmail.com. This is not to be used for the assessment, diagnosis or management of patients. It should not be regarded as medical advice. It is only for educational purposes. Please adhere to your local protocols. If you are unwell please seek healthcare advice from your doctor. This does not replace senior or specialist advice. If you do not accept this then please do not use the website. If you need medical advice, please consult a doctor or other appropriate medical professional. If you are a medical professional and you need advice then speak to your senior or colleagues.

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