Inflammatory bowel diseases

Clinical and morphological differences

Ulcerative colitis (Colitis ulcerosa) and Crohn's disease (Morbus Crohn) have fundamental differences in their disease course and the localization of the pathological process.

Ulcerative colitis proceeds with relapses and remissions; its classic symptom is diarrhea mixed with blood. Inflammation is strictly limited to the mucosal layer. The process always starts in the rectum and continuously spreads in a proximal direction. Endoscopy reveals a granular mucosa; over time, the bowel shortens and narrows. During the healing of acute extensive ulcers, post-inflammatory polyps (sessile or bridge-like mucosal projections) may form.

Crohn's disease presents with abdominal pain, diarrhea, and weight loss; peak incidence occurs at ages 20 and 50. Inflammation is transmural (involving all layers of the wall), leading to the formation of deep slit-like ulcers and fistulas. The involvement is asymmetric and patchy; the rectum is involved in only half of the patients, and 5% of patients show perianal involvement. A specific sign of CD is aphthous ulceration.

Features of IBD in childhood

In pediatric practice, inflammatory bowel diseases are more severe and have a different localization pattern compared to adult patients. In children, large bowel involvement in IBD is significantly more extensive.

• In pediatric UC, total involvement (pancolitis) predominates, whereas isolated proctosigmoiditis is atypical.
• In Crohn's disease, every second child has ileocolitis, and 10% have involvement of the upper GI tract (a rare occurrence in adults).

Of particular difficulty are extraintestinal manifestations, which can mimic other systemic diseases. For example, joint syndrome (arthritis) in UC requires differential diagnosis with juvenile idiopathic arthritis. Arthropathies are divided into peripheral (dependent on the activity of intestinal inflammation) and axial (sacroiliitis, whose course is autonomous). "Red flags" in children also include growth and pubertal delay, fever of unknown origin, and progressive weight loss.

Diagnostic algorithm

The basis for verifying the diagnosis is a comprehensive endoscopic examination. In children, the "gold standard" is a combination of ileocolonoscopy and upper endoscopy with mandatory multiple step-biopsies from various areas, including visually unchanged mucosa. Upper endoscopy is strictly necessary to exclude upper GI tract Crohn's disease.

To rule out an infectious origin of colitis (acute intestinal infections, clostridial enterocolitis, parasitoses), stool laboratory testing is performed. In particular, differential diagnosis from intestinal amebiasis requires searching for vegetative forms of Entamoeba histolytica in biopsy specimens or ulcer discharge.

Cross-sectional imaging (CT, MRI, ultrasound) is used as additional methods. The primary radiological sign of colitis is bowel wall thickening (greater than 4 mm). On high-resolution ultrasound in ulcerative colitis, the bowel wall typically preserves layer differentiation (stratification), whereas in chronic Crohn's disease, this stratification can be completely lost.

Class and exam questions

What else to study on this topic

• Pathogenesis and morphology of Hirschsprung's disease in children
• Spectrum of extraintestinal manifestations of IBD (skin, eye, and liver lesions)
• Montreal classification of inflammatory bowel diseases
• Differential diagnosis of IBD with antibiotic-associated colitides
• Radiological signs of complications: phlegmons and abscesses

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.