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Mesenteric Adenitis
Anne Walsh, MMSc, PA-C, DFAAPA
Kashyap Trivedi, MD
image BASICS
Inflammation of the mesenteric lymph nodes. A common cause of self-limited RLQ abdominal pain.
  • Characterized by benign inflammation of the mesenteric lymph nodes; can be acute or chronic
  • May clinically mimic acute appendicitis
  • Commonly misdiagnosed, making definitive incidence unknown
  • Most common cause of appendicitis-like pain in children (1)
    • 20% in patients presenting for appendectomy (2)
  • More common in children <15 years old than in adults
    • Primary adenitis is more common in children.
    • Secondary adenitis is more common in adults.
      • Rule out diverticulitis, appendicitis, Crohn disease, or systemic infectious/inflammatory disease (e.g., HIV, SLE).
Affects males and females equally.
  • Adenitis secondary to Yersinia infection is more prevalent in boys than girls.
    • Yersinia enterocolitica is most common in North America, Eastern Europe, and Australia.
  • Primary: underlying inflammatory process not present; presumed due to acute infectious gastroenteritis (specifically, terminal ileitis)
  • Secondary: underlying inflammatory process present (see “Commonly Associated Conditions”)
  • In infectious etiologies, pathogens are ingested, translocate through the intestinal epithelium via Peyer patches, and gain access to mesenteric lymph nodes. An inflammatory reaction within mesenteric lymph nodes causes symptoms and clinical disease. Infectious agents include:
    • Y. enterocolitica
    • Campylobacter jejuni
    • Salmonella typhi
    • &bgr;-Hemolytic Streptococcus spp.
    • Staphylococcus spp.
    • Streptococcus viridans
    • Escherichia coli
    • Mycobacterium tuberculosis
    • Giardia lamblia
    • Epstein-Barr virus (EBV)
    • Acute HIV infection
    • Rubeola virus
    • Cat-scratch disease
    • Adenovirus species
No known genetic susceptibility
  • Typically preceded by URI or pharyngitis
  • History of ingesting undercooked pork particularly in areas where Yersinia is endemic (parts of Europe).
Minimize risk by fully cooking foods, especially meat.
  • Appendicitis
  • Diverticulitis
  • Crohn disease
  • Celiac disease
  • Other systemic inflammatory/autoimmune disease
  • Fever; can have toxic appearance
  • Abdominal tenderness; (with or without rebound and often in the RLQ)
  • Peripheral/generalized lymphadenopathy
  • Rectal tenderness
  • Rhinorrhea
  • Pharyngeal hyperemia
  • Appendicitis, intussusception, intestinal duplication, regional enteritis (Crohn disease), Meckel diverticulitis, ulcerative colitis
  • Epiploic appendagitis, mesenteric ischemia
  • UTI, pyelonephritis
  • Salpingitis, PID, ectopic pregnancy
  • Neoplasm (e.g., lymphoma)
Initial Tests (lab, imaging)
  • CBC: leukocytosis with left shift
  • Basic metabolic panel may show electrolyte disturbances and azotemia if dehydrated and/or alkalotic from recalcitrant vomiting.
  • &bgr;-HCG in women of childbearing potential
  • Stool cultures if diarrhea
  • Serologies if specific infectious agent suspected
  • Blood cultures if septic
  • CT scan: enlarged mesenteric lymph nodes (larger in size, number, and distribution than appendicitis)
    • Specific CT appearance includes ≥3 clustered lymph nodes measuring at least 5 mm in the short axis, most commonly to the right of the psoas muscle (3)[B].
    • May or may not have evidence of ileal or ileocecal wall thickening
    • Appendix appears normal.
  • Ultrasound: less sensitive; used for exclusion of other potential diagnoses
    • Preferred in children and women (1)[C]
    • Used to evaluate for signs of appendicitis (96% positive predictive value in children) (2)[B]

Diagnostic Procedures/Other
Lymph node biopsy: only for those undergoing laparotomy can isolate the causative organism
Test Interpretation
  • Lymph nodes are enlarged and soft.
  • Adjoining mesentery may be edematous.
  • Microscopically, lymph nodes display nonspecific hyperplasia. If a suppurative infection is present, lymph nodes may contain necrotic material with pus formation.
    • Lymphatic sinuses may be enlarged.
    • If Y. enterocolitica infection, lymph node capsule may be thickened, with surrounding edema; lymph node hyperplasia, with plasma cell infiltration also occur.
First Line
  • Supportive and symptomatic treatment for uncomplicated cases
  • IV fluid resuscitation if hypovolemic
  • Correct underlying electrolyte aberrations.
  • Pain control
Second Line
  • Broad-spectrum antibiotic therapy for moderately to severely ill patients if diagnosis is unclear pending workup and/or surgical evaluation
  • Treatment duration varies based on cause and severity of illness. For uncomplicated cases, antibiotic treatment is not necessary.
Surgery is usually indicated in cases of suppuration and/or abscess formation, with signs of peritonitis, or if acute appendicitis cannot be excluded with certainty.
Admission Criteria/Initial Stabilization
  • Admit patients with complications and/or hemodynamic instability.
  • Volume resuscitation and correction of underlying electrolyte abnormalities
IV Fluids
  • IV fluids may be indicated for patients who cannot tolerate PO intake due to nausea or vomiting.
  • Aggressive fluid hydration is indicated if there is any evidence of sepsis.
Discharge Criteria
Hemodynamic stability, able to tolerate PO diet, able to follow up in the outpatient setting
Patient Monitoring
Close outpatient monitoring is needed to ensure total resolution of symptoms.
There are no specific dietary recommendations. Hold oral intake as necessary until nausea and vomiting resolve. Advance diet slowly as tolerated.
In cases of Yersinia infection, patients should avoid unpasteurized milk, raw pork, and contaminated water.
  • Generally self-limiting and benign condition
  • Increased morbidity/mortality for patients presenting with sepsis
1. Millet I, Alili C, Pages E, et al. Infection of the right iliac fossa. Diagn Interv Imaging. 2012;93(6):441-452.
2. Toorenvliet B, Vellekoop A, Bakker R, et al. Clinical differentiation between acute appendicitis and acute mesenteric lymphadenitis in children. Eur J Pediatr Surg. 2011;21(2):120-123.
3. Purysko AS, Remer EM, Filho HM, et al. Beyond appendicitis: common and uncommon gastrointestinal causes of right lower quadrant abdominal pain at multidetector CT. Radiographics. 2011;31(4):927-947.
Additional Reading
Patlas MN, Alabousi A, Scaglione M, et al. Crosssectional imaging of nontraumatic peritoneal and mesenteric emergencies. Can Assoc Radiol J. 2013;64(2):148-153.
I88.0 Nonspecific mesenteric lymphadenitis
Clinical Pearls
  • Mesenteric adenitis is an inflammatory process that mimics appendicitis. Diagnosis requires imaging to distinguish from acute appendicitis.
  • The condition is more common in children, often following a URI.
  • The treatment is generally supportive care.