What are the causes of mild mesenteric lymphadenitis?

Causes of Mild Mesenteric Lymphadenitis

The most common causes of mild mesenteric lymphadenitis are viral infections, followed by bacterial infections such as Yersinia pseudotuberculosis, nontuberculous mycobacteria (NTM), and less commonly, tuberculosis. Understanding these causes is essential for proper diagnosis and management to reduce morbidity and mortality.

Infectious Causes

Viral Infections

• Most common cause of mild mesenteric lymphadenitis
• Typically self-limiting
• Common viral pathogens include:
  • Cytomegalovirus (CMV) 1
  • Epstein-Barr virus (EBV) 1
  • Other common respiratory and enteric viruses

Bacterial Infections

Yersinia Species

• Yersinia pseudotuberculosis is a significant cause of mesenteric adenitis 2, 3, 4
• Presents with:
  • Fever
  • Abdominal pain mimicking appendicitis
  • Sometimes with palpable abdominal mass due to enlarged mesenteric nodes 2
• Diagnosis can be confirmed by:
  • Serological studies
  • Abdominal ultrasound
  • CT scan
  • Bacterial culture from biopsied material if performed 2

Mycobacterial Infections

• Nontuberculous mycobacteria (NTM):

  • Mycobacterium avium complex (MAC) accounts for approximately 80% of culture-proven cases of NTM lymphadenitis 5
  • Other NTM species include M. scrofulaceum, M. malmoense, and M. haemophilum 5
  • Typically affects children between 1-5 years old 5
  • Usually presents with unilateral, non-tender lymphadenopathy 5

• Tuberculosis (TB):

  • Tuberculous mesenteric lymphadenitis is rare but important to consider 6, 7
  • More common in immunocompromised patients
  • Can mimic other abdominal conditions including malignancy 6
  • Requires high index of suspicion, especially in patients from endemic areas 6

Campylobacter jejuni

• Important cause of mesenteric adenitis 1
• Most commonly associated with gastroenteritis
• Regional variations exist, with higher prevalence in areas with poor sanitation 1

Non-infectious Causes

Inflammatory Conditions

• Inflammatory bowel disease (IBD)
• Autoimmune disorders

Malignancy

• Lymphoma
• Metastatic disease
• Should be considered in persistent or progressive cases

Diagnostic Approach

Imaging

• Ultrasound: First-line imaging modality
  • Shows enlarged, hypoechoic mesenteric lymph nodes
• CT scan:
  • Shows asymmetric adenopathy with ring-enhancing masses in mycobacterial infections 5
  • Can help differentiate from other abdominal pathologies

Laboratory Tests

• Complete blood count
• Inflammatory markers (ESR, CRP)
• Serological tests for specific pathogens
• Tuberculin skin test when TB is suspected 5

Tissue Diagnosis

• Fine needle aspiration may be variable in utility 5
• Excisional biopsy provides definitive diagnosis but is invasive 5
• Histopathology typically shows:
  • Granulomatous inflammation in mycobacterial infections
  • Reactive lymphoid hyperplasia in viral infections

Management Considerations

• Most cases of viral mesenteric lymphadenitis are self-limiting and require only supportive care
• Bacterial causes may require specific antimicrobial therapy
• For NTM lymphadenitis, excisional surgery without chemotherapy is the recommended treatment for children 5
• For tuberculous lymphadenitis, anti-TB therapy is necessary 7
• Yersinia infections may be treated with appropriate antibiotics, avoiding unnecessary surgery 2

Clinical Pearls and Pitfalls

• Mesenteric lymphadenitis often mimics appendicitis, leading to unnecessary surgeries
• Consider mesenteric lymphadenitis in patients with right lower quadrant pain but without typical signs of appendicitis
• In immunocompromised patients, consider opportunistic infections like CMV and mycobacterial infections 5
• Persistent or progressive lymphadenopathy warrants further investigation to rule out malignancy
• Regional variations in causative organisms exist, with higher rates of gastroenteritis-associated mesenteric lymphadenitis in areas with poor sanitation 1

Understanding the various causes of mesenteric lymphadenitis is crucial for appropriate diagnosis and management, ultimately improving patient outcomes by avoiding unnecessary interventions while ensuring proper treatment of the underlying cause.