Crohn Disease

Snapshot

• A 18-year-old boy presents to his primary care physician for abdominal pain, diarrhea, and chronic fatigue. He reports that he has nonbloody diarrhea for the past few weeks. He could not identify any “bad” foods, and nobody else around him has the same symptoms. His aunt has a history of inflammatory bowel disease, but he is unsure which specific disease. He is noted to be underweight on physical exam. Laboratory results show elevated erythrocyte sedimentation rate (ESR) and C-reactive protein.  He is scheduled for a colonoscopy with biopsy to confirm the diagnosis.

Introduction

• Overview
  • Crohn disease is an inflammatory bowel disease that can affect any part of the gastrointestinal (GI) tract, including the mouth and the anus  
    • characterized by abdominal pain and nonbloody diarrhea
    • classically associated with non-contiguous involvement, or “skip lesions”, along GI tract
• Epidemiology
  • demographics
    • onset 15-30 years of age or 60-70s years of age
  • risk factors
    • family history
• Pathogenesis
  • mechanism
    • chronic Th1-mediated inflammation
      • starts as focal inflammatory infiltrates around crypts, evolves into transmural inflammation and noncaseating granulomas
• Prognosis
• unpredictable course of relapses and remissions

Presentation

• Symptoms 
  • GI symptoms
    • results from transmural involvement
    • abdominal pain
    • bloody or nonbloody diarrhea
    • abscess
    • fistulas  
    • strictures
    • malnutrition
  • extraintestinal manifestations
    • arthralgias
    • kidney stones
      • calcium oxalate 
    • ankylosing spondylitis
    • gallstones 
      • due to poor bile acid absorption at the ileum 
  • systemic symptoms
    • chronic intermittent fever
    • weight loss
    • fatigue
• Physical exam
  • skin and mucosal findings
    • pyoderma gangrenosum
    • erythema nodosum
    • aphthous stomatitis
    • perianal region
      • skin tags
      • scarring
  • ocular finding
    • episcleritis
• uveitis

Imaging

• Abdominal radiograph
  • indications
    • assess for bowel obstruction
• CT of abdomen
  • indications
• evaluation for obstruction, fistulas, or abscesses

Studies

• Serum labs
  • serology used when endoscopic studies and barium studies are inconclusive
    • anti-saccharomyces cerevisiae positive
    • anti-neutrophil cytoplasmic antibody negative
  • complete blood cell count
  • elevated inflammatory markers
• Invasive studies
  • colonoscopy or esophagogastroduodenoscopy
    • indication
      • diagnostic
    • findings
      • cobblestone mucosa 
      • skip lesions
      • bowel wall thickening 
      • ulcers
      • fissures
• Histology
  • noncaseating granulomas
• lymphoid aggregates

Differential

• Ulcerative colitis
  • key distinguishing factors
    • bloody diarrhea
    • disease affecting colon and always the rectum
• mucosal and submucosal inflammation only

Treatment

• Medical
  • 5-aminosalicylic acid agents
    • indications
      • mild disease
      • initial therapy
    • drugs
      • mesalamine
        • best initial therapy
      • sulfasalazine
  • corticosteroids
    • indications
      • for flares
  • immunosuppressive agents
    • drugs
      • infliximab / adaliumumab
        • good for those with fistula formation
        • necessary for disease remission
        • antibodies targeted against tumor necrosis factor alpha 
      • azathioprine
        • recurrent symptoms off steroids
  • antibiotics
    • drugs
      • metronidazole/ciprofloxacin
        • perianal involvement
  • anti-diarrheal medications
    • drugs
      • loperamide
• Surgical
  • surgical resection of affected area
    • indications
• not curative

Complications

• Fistula formation
• Colorectal cancer
• Abscesses
• Strictures