What does erosive chronic active ileitis on pathology mean and does it require further workup?

Erosive Chronic Active Ileitis: Diagnosis and Management

Erosive chronic active ileitis on pathology strongly suggests inflammatory bowel disease (IBD) and requires further diagnostic workup to determine the specific etiology and guide appropriate treatment.

Understanding the Pathology Finding

Erosive chronic active ileitis refers to inflammation of the terminal ileum characterized by:

• Mucosal erosions (breakdown of the epithelial lining)
• Active inflammation (presence of neutrophils)
• Chronic inflammatory changes (architectural distortion, crypt abnormalities)

This pathological finding is most commonly associated with:

1. Crohn's disease (most common cause of terminal ileitis) 1
2. "Backwash ileitis" in ulcerative colitis (seen in up to 20% of patients with extensive colitis) 2, 3
3. Other potential causes including:
   • NSAID-induced enteropathy
   • Infectious ileitis
   • Vasculitis
   • Spondyloarthropathies 4

Required Further Workup

1. Clinical Correlation

• Detailed symptom assessment (abdominal pain, diarrhea, rectal bleeding)
• Medication history (particularly NSAIDs)
• Family history of IBD
• Extra-intestinal manifestations (joint pain, skin lesions, eye inflammation)

2. Laboratory Testing

• Complete blood count
• Inflammatory markers (CRP, ESR)
• Stool studies:
  • Cultures for infectious causes
  • Fecal calprotectin (to assess inflammation)
  • C. difficile testing
  • Parasites 2

3. Imaging Studies

• Cross-sectional imaging is essential:
  • CT or MR enterography to evaluate:
    • Disease extent
    • Presence of strictures
    • Fistulas
    • Abscesses
    • Other small bowel involvement 1

4. Endoscopic Assessment

• Complete ileocolonoscopy with biopsies from multiple sites:
  • Terminal ileum
  • Colon (multiple segments)
  • Rectum 2
• Consider upper endoscopy with biopsies (especially if Crohn's disease is suspected) 2

Diagnostic Considerations

Differentiating Crohn's Disease vs. Ulcerative Colitis with Backwash Ileitis

• Backwash ileitis in UC:

  • Usually mild (villous atrophy, increased inflammation, scattered crypt abscesses)
  • Generally continuous with cecal inflammation
  • Parallels severity of colonic disease 3

• Crohn's ileitis:

  • More severe erosions/ulcerations
  • May occur without colonic involvement
  • Often discontinuous/patchy inflammation
  • May have transmural inflammation 1

Other Important Considerations

• Approximately 30% of patients with isolated ileal erosions may develop typical Crohn's disease after a mean interval of 3.6 years 5
• Focal enhanced gastritis (FEG) is more commonly present in Crohn's disease patients (36%) than in non-Crohn's disease patients (5%) and can help with diagnosis 6
• NSAID use should be carefully assessed as it can cause similar findings 7, 5

Management Approach

Management depends on the confirmed diagnosis:

If Crohn's Disease:

• For mild ileocolonic disease: high-dose mesalazine (4 g/daily) 2
• For moderate to severe disease: oral corticosteroids (prednisolone 40 mg daily) 2
• For severe disease: intravenous steroids with concomitant metronidazole 2
• Consider immunomodulators or biologics for maintenance therapy 2

If Ulcerative Colitis with Backwash Ileitis:

• Treat according to the extent and severity of colonic disease
• Maintenance therapy with aminosalicylates, azathioprine, or mercaptopurine 2

If NSAID-Induced:

• Discontinuation of the offending drug 1

If Infectious:

• Appropriate antimicrobial therapy based on identified pathogen 1

Follow-up Recommendations

• Repeat endoscopic assessment to monitor response to therapy
• Fecal calprotectin monitoring to assess disease activity
• Regular clinical follow-up to assess for symptom improvement

Pitfalls to Avoid

1. Misdiagnosing isolated ileal erosions as definitive Crohn's disease without adequate follow-up
2. Failing to consider NSAID use as a potential cause
3. Not performing adequate cross-sectional imaging to assess for complications
4. Overlooking the possibility of backwash ileitis in patients with ulcerative colitis
5. Neglecting to obtain biopsies from multiple sites during endoscopy

Remember that distinguishing between the various forms of ileitis requires careful clinical assessment, appropriate laboratory testing, and correlation of endoscopic and radiologic data with pathology findings.