Mesenteric Adenitis
Mesenteric adenitis is inflammation and enlargement of the mesenteric lymph nodes, typically causing acute abdominal pain that can mimic appendicitis
Scope: This article focuses on primary (non-specific) mesenteric adenitis, where no underlying intra-abdominal inflammatory cause is identified.
Secondary mesenteric lymphadenopathy occurs due to another condition (e.g. Crohn’s disease, ulcerative colitis) and is managed according to the underlying cause
Causes and Risk Factors
Most cases are associated with a viral infection → reactive lymphadenopathy (typically around the terminal ileum / ileocaecal region) [Ref]
- Often occurs during or shortly after an URTI
- Associated enteric infections
- Yersinia enterocolitica
- Non-typhoidal Salmonella
Mesenteric adenitis occurs mainly in children, adolescents, and young adults [Ref]
- It is uncommon after 20 years of age
Clinical Features
Often follows or occurs alongside a recent URTI [Ref]
- Acute abdominal pain
- Location: periumbilical and/or RIF
- May range from discomfort to severe colicky pain
- Abdominal tenderness (usually maximal in the RIF)
- Nausea / vomiting
- Change in bowel habit (e.g. diarrhoea, altered stool frequency or consistency)
- +/- Fever
The patient is often NOT systemically unwell despite significant abdominal pain
Investigation and Diagnosis
Mesenteric adenitis often presents similarly to acute appendicitis, so patients are commonly investigated as part of an acute abdomen / suspected appendicitis work-up
| Blood tests [Ref] | FBC and CRP
Exam note: WCC and CRP may be normal or mildly–moderately elevated in mesenteric adenitis Normal / less markedly raised inflammatory markers may support mesenteric adenitis over appendicitis in an exam scenario. However, this is not a reliable discriminator in practice as inflammatory marker levels overlap between the 2 conditions and should be interpreted alongside the clinical picture and imaging findings. |
| Urinalysis [Ref] | May be performed to exclude UTI |
| Imaging [Ref] | 1st line (in children): abdominal ultrasound
Typical finding:
Ultrasound can also be used to exclude other abdominopelvic pathology (e.g. intussusception, ectopic pregnancy, ovarian torsion) |
Mesenteric Adenitis vs Acute Appendicitis
| Mesenteric adenitis | Acute appendicitis | |
|---|---|---|
| Clinical features | Often recent URTI
Pain commonly periumbilical and/or RIF Less guarding / rigidity Often relatively well systemically |
Pain classically migrates from periumbilical region → RIF
Anorexia is common Guarding / rigidity / rebound tenderness is more likely Systemic upset may develop |
| Laboratory tests | WCC and CRP may be normal or mildly–moderately raised | WCC and CRP are often raised |
| Imaging | Ultrasound: enlarged mesenteric lymph nodes + normal appendix | Ultrasound: inflamed appendix +/- reactive mesenteric lymphadenopathy |
Management
Mesenteric adenitis is self-limiting [Ref]
Management is conservative (once surgical problems e.g. acute appendicitis, have been excluded): [Ref]
- Ensure adequate hydration
- Analgesia (e.g. paracetamol +/- NSAIDs)
- Reassurance and safety-netting (symptoms generally improve over 2-4 weeks)
If appendicitis cannot be confidently excluded despite clinical assessment and imaging → surgical review for potential diagnostic laparoscopy. [Ref]
If laparoscopy identifies mesenteric adenitis with a macroscopically normal appendix, management of the appendix varies by surgical practice, as routine removal of a normal appendix remains controversial. [Ref]
References
Bibliography
- Di Saverio S, Podda M, De Simone B, et al. Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines. World Journal of Emergency Surgery. 2020;15:27.
- Helbling R, Conficconi E, Wyttenbach M, Benetti C, Simonetti GD, Bianchetti MG, Hamitaga F, Lava SAG, Fossali EF, Milani GP. Acute Nonspecific Mesenteric Lymphadenitis: More Than “No Need for Surgery”. BioMed Research International. 2017;2017:9784565