How to diagnose lupus enteritis?

Diagnosis of Lupus Enteritis

Lupus enteritis should be diagnosed using a combination of clinical presentation, laboratory markers of SLE activity, and characteristic CT imaging findings including target sign, comb sign, and increased mesenteric fat attenuation.

Clinical Presentation

• Abdominal pain (typically diffuse)
• Diarrhea
• Nausea and vomiting
• Fever
• Weight loss

Laboratory Evaluation

• Complete blood count (CBC)
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) - typically elevated
• Serum albumin - may be decreased
• Complement levels (C3, C4) - typically decreased during active disease 1
• Autoantibody panel:
  • Anti-nuclear antibodies (ANA)
  • Anti-double-stranded DNA (anti-dsDNA) - correlates with disease activity 1
  • Anti-Smith (anti-Sm)
  • Anti-ribonucleoprotein (anti-RNP)
  • Anti-Ro/SSA and anti-La/SSB antibodies
  • Anti-phospholipid antibodies

Imaging Studies

• CT scan of the abdomen is the diagnostic modality of choice 2
• Key CT findings:
  • Target sign (circumferential bowel wall thickening with two or more concentric rings)
  • Comb sign (engorgement of mesenteric vessels)
  • Increased mesenteric fat attenuation
  • Ascites (commonly present)
  • Marked circumferential wall thickening and edema of small bowel 3
• Ultrasonography may show:
  • "Accordion-like appearance" of intestinal wall 4
  • Edematous thickening of the small intestine

Differential Diagnosis

• Infectious enteritis
• Mesenteric ischemia or thrombosis
• Inflammatory bowel disease
• Intestinal angioedema
• Intestinal tuberculosis
• Medication side effects

Exclusionary Tests

• Stool cultures and microscopy to rule out infectious causes
• Mesenteric angiography or CT angiography to rule out mesenteric thrombosis
• C1 esterase inhibitor levels to rule out hereditary angioedema 3

Endoscopic Evaluation

• Endoscopic appearance and biopsies usually yield non-specific findings 3
• May be considered if diagnosis remains uncertain or to rule out other conditions

Diagnostic Algorithm

1. In SLE patients presenting with abdominal symptoms, first rule out common causes:

   • Medication side effects
   • Infections
   • Other underlying conditions

2. If common causes are excluded, proceed with:

   • Laboratory tests for SLE activity (complement levels, anti-dsDNA)
   • CT scan of abdomen with contrast

3. Diagnosis of lupus enteritis is confirmed when:

   • Characteristic CT findings are present
   • Laboratory evidence of active SLE
   • Other causes of enteritis are excluded

Complications to Monitor

• Bowel perforation
• Gastrointestinal hemorrhage 5
• Intestinal pseudo-obstruction 6
• Bowel necrosis 2

Treatment Considerations

Once diagnosed, prompt treatment with high-dose corticosteroids (methylprednisolone 60 mg IV daily) is indicated 3, with addition of other immunosuppressants for severe or refractory cases.

Pitfalls to Avoid

• Delaying diagnosis due to non-specific symptoms
• Failing to consider lupus enteritis when GI symptoms are the sole manifestation of SLE flare 2
• Missing concurrent infections that may mimic or complicate lupus enteritis 7
• Inadequate monitoring for potentially life-threatening complications

Lupus enteritis should be considered in any patient with known SLE presenting with abdominal symptoms, particularly when accompanied by laboratory evidence of disease activity, even if there are no other active manifestations of lupus.