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

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

The first-line treatment for this 13-year-old girl with Crohn's disease showing transmural inflammation on colonoscopy is exclusive enteral nutrition (EEN), not systemic steroids, unless high-risk features are present. 1, 2

Risk Stratification Determines Treatment Choice

The critical first step is determining whether this patient has high-risk features that would mandate immediate escalation to anti-TNF therapy rather than standard first-line options. 1

High-risk features include: 1, 3

• Severe growth retardation (height Z-score < -2.5), especially in Tanner stages 2-3
• Perianal fistulizing disease
• Deep colonic ulcerations on endoscopy
• Extensive pan-enteric disease (including upper GI and proximal small bowel)
• Stricturing or penetrating disease behavior

If high-risk features are present: Anti-TNF therapy (infliximab) becomes the first-line treatment, bypassing both EEN and systemic steroids. 1, 2, 3

If high-risk features are absent: Exclusive enteral nutrition is the recommended first-line therapy. 1, 2

Why Exclusive Enteral Nutrition is Preferred Over Systemic Steroids

EEN achieves comparable remission rates to corticosteroids (73% vs 73%) but with superior outcomes for pediatric-specific concerns: 1, 2

• Promotes mucosal healing while restoring bone mineral density and supporting linear growth—critical developmental outcomes in a 13-year-old. 1, 2
• Avoids steroid-related toxicity including growth suppression, bone density loss, and metabolic complications that are particularly detrimental during adolescence. 2
• Duration: 6-8 weeks of exclusive liquid formula (whole-protein formula taken orally). 1, 2
• Early response check: If no clinical improvement occurs within 2 weeks, switch to an alternative therapy. 1, 2

The ECCO/ESPGHAN consensus guidelines explicitly state that EEN should be preferred over corticosteroids for all children with inflammatory luminal disease, including those with colonic involvement. 1, 2

Why the Other Options Are Not First-Line

Systemic steroids (Option A): While effective for rapid symptom control, steroids are inferior to EEN in pediatric patients because they suppress growth, reduce bone density, and provide no advantage in remission rates. 1, 2 Steroids should be reserved for situations where EEN fails or cannot be implemented, or when high-risk features mandate immediate anti-TNF therapy. 1

Infliximab (Option B): Reserved for high-risk patients at diagnosis or after failure of first-line therapy. 1, 2 Without documented high-risk features (severe growth retardation, perianal disease, deep ulcers, extensive disease), starting with infliximab represents overtreatment and exposes the patient to unnecessary immunosuppression risks. 1

Methotrexate (Option C): Not suitable for induction therapy because its therapeutic effect requires 2-3 months to manifest. 1 Methotrexate is a second-line maintenance agent used after thiopurine failure, not for initial remission induction. 1

Practical Implementation

EEN protocol: 1, 2

• Administer whole-protein liquid formula exclusively for 6-8 weeks
• Use elemental formula only if cow's milk protein allergy is documented
• Nasogastric tube may be considered if oral intake is inadequate, but balance quality of life concerns
• Gradually reintroduce solid foods over 2-3 weeks while reducing formula volume

If EEN fails at 2 weeks: Transition to systemic corticosteroids (prednisone 1 mg/kg/day, maximum 40 mg, tapered over ~10 weeks) or consider anti-TNF therapy depending on disease severity. 1

Common Pitfall to Avoid

The presence of transmural inflammation on colonoscopy does not automatically indicate high-risk disease requiring anti-TNF therapy. 2 Transmural inflammation is a characteristic pathologic feature of Crohn's disease itself. 4, 5 The decision to escalate to biologics depends on the specific high-risk clinical features listed above, not simply on the transmural nature of the inflammation. 1, 3

Answer: D - Manage nutrition (exclusive enteral nutrition) is the correct first-line option for this patient, assuming no high-risk features are documented in the clinical presentation.