What is the first‑line therapy to induce remission in a 13‑year‑old female with chronic diarrhea and transmural inflammation on colonoscopy consistent with Crohn disease?

First-Line Treatment for Pediatric Crohn's Disease with Transmural Inflammation

Exclusive enteral nutrition (EEN) is the recommended first-line therapy to induce remission in this 13-year-old female with Crohn's disease, even with transmural inflammation and colonic involvement. 1

Rationale for EEN as First-Line Therapy

The ECCO/ESPGHAN consensus guidelines explicitly state that EEN should be preferred over corticosteroids for all children with inflammatory intestinal luminal disease, including colonic involvement 1. This recommendation is based on:

• Superior outcomes beyond symptom control: EEN promotes mucosal healing, restores bone mineral density, and improves linear growth—critical outcomes in a 13-year-old who is likely in active puberty 1
• Remission rate of 73% in pediatric Crohn's disease, comparable to corticosteroids but without the adverse effects 1
• Avoidance of corticosteroid toxicity: Growth suppression, bone density loss, and metabolic complications are particularly problematic in adolescents 1

Practical Implementation

• Duration: 6–8 weeks of exclusive liquid formula 1
• Formula type: Whole protein formula given orally; elemental formulas only if cow's milk protein allergy exists 1
• Response assessment: If no clinical response within 2 weeks, switch to alternative therapy 1
• Food reintroduction: Gradual over 2–3 weeks with concomitant decrease in formula volume 1

When to Choose Alternative First-Line Therapy

Systemic corticosteroids (prednisone 1 mg/kg once daily, maximum 40 mg) become first-line only if:

• The patient has high-risk features requiring immediate anti-TNF therapy instead 1, 2:

  • Severe perianal disease 1, 2
  • Severe growth retardation (height Z-score < -2.5) in Tanner stage 2-3 1, 2
  • Deep colonic ulcerations on endoscopy 1, 2
  • Extensive pan-enteric disease 1

• EEN is not feasible due to patient/family refusal or inability to maintain exclusive liquid diet 1

In high-risk patients, early anti-TNF therapy (infliximab) should be initiated rather than waiting for corticosteroid or EEN failure 1, 2.

Why Other Options Are NOT First-Line

Infliximab (Option B) is reserved for:

• High-risk patients at diagnosis 1, 2
• Failure of EEN or corticosteroids 1
• Steroid-dependent disease 1

Methotrexate (Option C) is inappropriate for induction because:

• Onset of action is 2–3 months, too slow for active disease 1, 2
• Used only as second-line maintenance after thiopurine failure 1

Systemic steroids (Option A) are effective but:

• Must be tapered over ~10 weeks and never used for maintenance 1
• Repeated courses or steroid dependency should not be tolerated 1
• Inferior to EEN in pediatric patients regarding growth and bone health 1

Critical Monitoring After EEN Initiation

• Clinical response assessment at 2 weeks: Switch therapy if no improvement 1
• Fecal calprotectin and CRP to track inflammatory activity 2
• Ileocolonoscopy at 6–9 months to verify mucosal healing 2
• Growth parameters and bone density as markers of disease control 1

Common Pitfall to Avoid

Do not assume this patient requires immediate biologic therapy simply because transmural inflammation is present. Transmural involvement is a defining feature of Crohn's disease 3, 4, not automatically an indication for anti-TNF therapy. The decision to escalate to biologics depends on the presence of specific high-risk features (perianal disease, severe growth failure, deep ulcerations, extensive disease) 1, 2, not merely the depth of inflammation.

The correct answer is D: Exclusive enteral nutritional formula.