What are the diagnostic and treatment approaches for a 5-month-old infant suspected of having very early onset Inflammatory Bowel Disease (IBD)?

Symptoms and Diagnostic Approach for Very Early Onset IBD in 5-Month-Old Infants

For a 5-month-old infant suspected of having very early onset inflammatory bowel disease (VEOIBD), a comprehensive diagnostic workup is essential, including ileocolonoscopy with biopsies and upper GI endoscopy, as these infants often have distinct pathological features and may have underlying immune deficiencies requiring specialized management. 1

Clinical Presentation of VEOIBD in Infants

• Failure to thrive is a common presenting symptom in infants with VEOIBD, particularly in those who will ultimately be diagnosed with Crohn's disease (CD) or indeterminate colitis (IC) 2
• Linear growth failure is frequently observed in young children with CD, affecting approximately 29% of children under 5 years with CD 2
• Diarrhea, often bloody, that persists beyond the typical viral gastroenteritis course (2-3 days) should raise suspicion for VEOIBD 3
• Infants with VEOIBD may present with more extensive colitis and less ileitis compared to older children and adults 1
• Perianal disease is common in very young children with CD, affecting up to 34% of patients under 5 years 2

Diagnostic Approach

Endoscopic Evaluation

• Ileocolonoscopy with biopsies is essential for all infants with suspected VEOIBD 1, 4
• Upper gastrointestinal endoscopy (esophagogastroduodenoscopy or EGD) is mandatory in pediatric patients with suspected IBD, particularly in infants, to improve diagnostic accuracy and differentiate between CD and UC 1, 5
• Multiple biopsies should be obtained from the ileum and each colonic segment, including the rectum, to assess disease distribution 4, 1
• Biopsies should be taken from both abnormal and normal-appearing areas to detect microscopic inflammation 4

Histopathological Features

• Infants with VEOIBD show distinct histopathological features compared to older children, including:
  • Increased frequency of apoptosis 6
  • Severe chronic architectural changes 6
  • Small intestine villous blunting 6
  • Increased eosinophils in the crypts, lamina propria, and surface epithelium 6
• The presence of granulomas in biopsies is more frequent in pediatric patients and can aid in diagnosis of CD 1, 5
• Basal plasmacytosis is an early histological feature with high predictive value for UC diagnosis 4

Laboratory Assessment

• Complete blood count to assess for anemia, which is a common complication of IBD 4
• Serum ferritin, transferrin saturation, and iron studies to evaluate for iron deficiency anemia 4
• Fecal calprotectin is a sensitive marker for intestinal inflammation and can help differentiate IBD from other conditions 1, 3
• C-reactive protein and erythrocyte sedimentation rate to assess inflammatory status 7

Additional Investigations

• Small bowel capsule endoscopy may be considered in older children but is not typically used in infants due to size constraints 4
• Cross-sectional imaging such as MR enterography or intestinal ultrasound may be helpful to assess disease extent and complications 8
• Genomic testing should be considered for VEOIBD patients to identify potential monogenic disorders, as children under 6 years with IBD may have underlying immune deficiencies 1

Special Considerations for Infants

• VEOIBD in infants under 6 years of age may represent a distinct entity with more severe disease behavior 1
• The diagnosis of indeterminate colitis (IC) should be avoided based solely on endoscopic biopsies due to high potential for diagnostic error 4
• In severe, active disease, full colonoscopy carries a higher risk of bowel perforation (0.3% to 1%), and initial flexible sigmoidoscopy may be safer 4
• Growth parameters should be carefully monitored, as growth failure is a unique challenge in pediatric IBD 1

Common Pitfalls to Avoid

• Failing to consider VEOIBD as a potential manifestation of underlying immune deficiency in infants 1
• Misdiagnosing VEOIBD as infectious gastroenteritis due to overlapping symptoms 3
• Inadequate biopsy sampling, which may lead to missed diagnosis or misclassification of disease 4
• Not performing upper GI endoscopy, which is essential for accurate diagnosis and classification of pediatric IBD 1, 5
• Relying solely on serological markers like ASCA, which may have limited diagnostic value in very young children with IBD 2

By following this comprehensive diagnostic approach, clinicians can accurately diagnose VEOIBD in 5-month-old infants and develop appropriate management strategies for these challenging cases.