BASICS
Inflammation of the mesenteric lymph nodes. A common cause of self-limited RLQ abdominal pain.
DESCRIPTION
- Characterized by benign inflammation of the mesenteric lymph nodes; can be acute or chronic
- May clinically mimic acute appendicitis
EPIDEMIOLOGY
- 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).
Prevalence
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.
ETIOLOGY AND PATHOPHYSIOLOGY
Genetics
No known genetic susceptibility
RISK FACTORS
- Typically preceded by URI or pharyngitis
- History of ingesting undercooked pork particularly in areas where Yersinia is endemic (parts of Europe).
GENERAL PREVENTION
Minimize risk by fully cooking foods, especially meat.
COMMONLY ASSOCIATED CONDITIONS
- Appendicitis
- Diverticulitis
- Crohn disease
- Celiac disease
- Other systemic inflammatory/autoimmune disease
DIAGNOSIS
HISTORY
The onset of symptoms is variable; nausea or abdominal pain is usually the initial presenting symptom. Symptoms are often nonspecific.
- Nausea and vomiting (may precede abdominal pain)
- Abdominal pain: periumbilical, RLQ
- Diarrhea
- Fever, malaise, fatigue, anorexia
- Recent history of upper respiratory tract infection
PHYSICAL EXAM
- Fever; can have toxic appearance
- Abdominal tenderness; (with or without rebound and often in the RLQ)
- Peripheral/generalized lymphadenopathy
- Rectal tenderness
- Rhinorrhea
- Pharyngeal hyperemia
DIFFERENTIAL DIAGNOSIS
- 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)
DIAGNOSTIC TESTS & INTERPRETATION
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.
- ²-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.
TREATMENT
MEDICATION
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/OTHER PROCEDURES
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.
INPATIENT CONSIDERATIONS
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
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Patient Monitoring
Close outpatient monitoring is needed to ensure total resolution of symptoms.
DIET
There are no specific dietary recommendations. Hold oral intake as necessary until nausea and vomiting resolve. Advance diet slowly as tolerated.
PATIENT EDUCATION
In cases of Yersinia infection, patients should avoid unpasteurized milk, raw pork, and contaminated water.
PROGNOSIS
- Generally self-limiting and benign condition
- Increased morbidity/mortality for patients presenting with sepsis
COMPLICATIONS
- Increased GI losses leading to hypovolemia and electrolyte imbalance
- Abscess formation, peritonitis, sepsis
- Latent extraintestinal manifestations, including arthralgias, truncal and extremity rashes, and erythema nodosum with Y. enterocolitica infection
- Postinfectious chronic complications of Yersinia infection including reactive arthritis, conjunctivitis, urethritis; postinfectious irritable bowel syndrome
REFERENCES
11 Millet I, Alili C, Pages E, et al. Infection of the right iliac fossa. Diagn Interv Imaging. 2012;93(6):441 " 452.22 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 " 123.33 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. Cross-sectional imaging of nontraumatic peritoneal and mesenteric emergencies. Can Assoc Radiol J. 2013;64(2):148 " 153.
CODES
ICD10
I88.0 Nonspecific mesenteric lymphadenitis
ICD9
289.2 Nonspecific mesenteric lymphadenitis
SNOMED
- 267548000 Nonspecific mesenteric adenitis
- 49631001 Acute mesenteric adenitis
- 191377002 Chronic mesenteric lymphadenitis (disorder)
- 44897000 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.