Crohn’s Disease

By usmlevideoss

Introduction

Crohn’s disease (CD) is a chronic inflammatory bowel disease (IBD) characterized by patchy, transmural inflammation that can affect any part of the gastrointestinal (GI) tract from the mouth to the anus. It commonly involves the terminal ileum and colon. Unlike ulcerative colitis, it is characterized by skip lesions and a relapsing-remitting course.

Etiology

Genetic factors:

  •  Mutations in the NOD2 gene are associated with increased risk.
  •  Family history of IBD increases susceptibility.

Immune dysregulation:

  • Dysregulated immune response to gut microbiota.
  • Overactivation of Th1 and Th17 cells.

Environmental factors:

  • Smoking (increases risk and severity).
  • Diet (e.g., high-fat or processed foods).
  • Use of nonsteroidal anti-inflammatory drugs (NSAIDs).

Epidemiology

  • Incidence: 3-20 cases per 100,000 people annually.
  • Prevalence: More common in North America, Europe, and Australia.
  • Peak age of onset: 15-30 years.
  • Slight female predominance.

Pathophysiology

1.Transmural inflammation:

  • Affects all layers of the bowel wall.

2.Skip lesions:

  • Discontinuous areas of inflammation with normal mucosa in between.

3.Granuloma formation:

  • Non-caseating granulomas may be seen in affected tissue.

4.Cobblestone appearance:

  • Due to linear ulcers and edematous mucosa.

5.Fistulas and strictures:

  • Chronic inflammation can lead to bowel wall fibrosis and fistula formation.

Clinical Manifestations

  • General symptoms:
    • Fatigue, weight loss, low-grade fever.
  • Intestinal symptoms:
  1. Ileocolitis:
  • Recurrent right lower quadrant (RLQ) pain.
  • Chronic diarrhea (sometimes bloody).
  • Fistulas and abscesses.
  1. Jejunoileitis:
  • Malabsorption, steatorrhea.
  • Vitamin and mineral deficiencies (e.g., B12, iron, zinc).

3.Colitis and perianal disease:

  • Diarrhea, crampy abdominal pain.
  • Perianal fistulas, abscesses, and strictures.

4.Gastroduodenal disease:

  • Epigastric pain, nausea, and vomiting.
  • Extraintestinal manifestations:
  • Arthritis, uveitis, erythema nodosum, pyoderma gangrenosum, and primary sclerosing cholangitis.

Diagnosis

1.Laboratory tests:

  • Elevated inflammatory markers (CRP, ESR).
  • Anemia, hypoalbuminemia.
  • Stool tests to exclude infections (e.g., fecal calprotectin).

2.Imaging:

  • CT or MR enterography: Bowel wall thickening, strictures, fistulas.
  • “String sign” on barium studies.
  1. Endoscopy:
  • Patchy erythema, ulcers, skip lesions, cobblestone appearance.
  • Biopsy: Transmural inflammation, non-caseating granulomas.

Treatment

1.Medical management:

  • Induction therapy:
    • Corticosteroids (e.g., prednisone) for acute flares.
  • Maintenance therapy:
  • Immunosuppressants (azathioprine, methotrexate).
  • Biologic agents (anti-TNF: infliximab, adalimumab).
  • Small molecules (JAK inhibitors, integrin blockers).
  • Antibiotics for abscesses or fistulas.

2.Nutritional support:

  • Address deficiencies (iron, vitamin B12, folate, calcium, vitamin D).

3.Surgery:

  • Reserved for complications (e.g., strictures, perforations, abscesses, refractory disease).

Prognosis

  • Chronic, relapsing disease with variable severity.
  • Complications include strictures, fistulas, malabsorption, and increased risk of colorectal cancer.
  •  With appropriate treatment, many patients achieve remission.

SUPERPoint

Crohn’s disease is a chronic, transmural inflammatory condition that commonly affects the terminal ileum and colon, with hallmark features including skip lesions, cobblestone appearance, and extraintestinal manifestations.

SUPERFormula

Patient presents with recurrent abdominal pain + diarrhea (bloody or non-bloody) + skip lesions and cobblestone appearance on endoscopy + transmural inflammation on biopsy = Crohn’s disease.