A.26 Crohn's Disease Flashcards
A.26 Crohn’s Disease
Crohn disease (CD) is an inflammatory bowel disease (IBD) of unclear etiology. Unlike ulcerative colitis, CD is not limited to the colon but can manifest anywhere in the gastrointestinal tract.
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Epidemiology:
Prevalence: 200 per 100,000 population
Incidence: 6 per 100,000 population
Typical Age of Onset: Bimodal distribution with a peak at 15-35 years and another at 55-70 years
Geographic Distribution: More common in Northern European descent and Ashkenazi Jewish individuals
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Etiology:
Causes: Immune dysregulation and dysbiosis, affecting intestinal function and leading to inflammation.
Risk Factors: Tobacco use, which is a notable environmental risk factor for Crohn’s disease. Smoking cessation is particularly important for those diagnosed.
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Pathphysiology
Inflammation is most likely caused by immune dysregulation.
- Dysregulation of IL-23-Th17 signaling → unrestrained Th17 cell function → inflammation → local tissue damage (edema, erosions/ulcers, necrosis) → obstruction, fibrotic scarring, stricture, and strangulation of the bowel [5]
- Mutations in the nucleotide oligomerization binding domain 2 (NOD2) protein are likely involved in the development of CD.
Abscess and fistula formation
Intestinal aphthous ulcers → transmural fissures and inflammation of the intestinal walls → adherence of other organs or the skin → penetration of tissue → microperforation and abscess formation → macroperforation into these structures → fistula formation
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Clinical Features
Crohn’s disease often presents episodically, with a 30% risk of recurring inflammation.
If symptoms persist for more than 6 months, the disease is considered chronic.
Constitutional Symptoms:
- Low-grade fever
- Weight loss
- Fatigue
Intestinal Symptoms:
The disease commonly affects the terminal ileum and can involve other areas of the gastrointestinal tract.
- Chronic diarrhea
- Abdominal pain, particularly in the right lower quadrant (RLQ)
- Malabsorption
- Palpable abdominal mass in the RLQ
- Oral aphthae (sores)
Note: Perianal fistulas and abscesses often indicate the initial signs of Crohn’s disease.
Extraintestinal Symptoms:
- Joints: Enteropathic arthritis (including spondylitis, spondylodiscitis, and arthritis)
- Eyes: Uveitis, episcleritis
- Liver/Bile Ducts: Conditions such as cholangitis and bile duct strictures
- Skin: Erythema nodosum, Pyoderma gangrenosum, Often associated with severe disease activity. Manifestations related to nutrient deficiencies, leading to conditions such as psoriasis or dermatitis; these may be treated with steroids or immunosuppressants.
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Diagnostics
Diagnosing Crohn’s Disease (CD) involves integrating clinical presentation with laboratory tests, as well as endoscopic, histologic, pathologic, and radiologic findings.
Laboratory Tests
Blood Work:
- A complete blood count may reveal signs of anemia, which can be indicative of conditions like pernicious anemia.
Serology:
- Testing for inflammatory markers (e.g., CRP, ESR, thrombocytes, and white blood cells) is essential.
- Anti-Saccharomyces cerevisiae antibodies (ASCA) may be measured; however, routine serologic testing is generally not recommended for diagnosis.
Stool Analysis:
- Conducted to rule out bacterial gastrointestinal infections:
- Microscopic Examination: To identify the presence of worms or eggs (indicative of parasitic infections).
- Identification of Bacterial Toxins: Such as the toxin from Clostridium difficile.
- Fecal Calprotectin and/or Fecal Lactoferrin: These markers can indicate intestinal inflammation and may be used as part of the diagnostic approach for inflammatory bowel disease (IBD).
- Fecal Occult Blood Test (FOBT): This may help identify hidden blood in the stool, which can be a sign of underlying pathology.
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Diagnostics - Imaging
Plain X-ray of the abdomen: May reveal bowel obstruction or pneumoperforation.
Barium Swallow and Small Bowel Follow-Through: Utilized to detect fistulas or strictures, examining specific features such as:
- String Sign: Indicates a narrowed segment resembling a string.
- Creeping Fat: Suggests pathologic thickening of adipose tissue associated with inflammation.
Ultrasound Findings:
- Wall Thickening: Typically observed in cases of abscesses or fistulas.
MR Enterography:
- A noninvasive, high-sensitivity imaging technique that complements endoscopic evaluations and is utilized in diagnosing inflammatory bowel disease (IBD).
- Key Findings: Observation of motility issues and lymph node enlargement linked to IBD.
Endoscopic Evaluation
Endoscopy:
Evaluates the extent of the disease, differentiating Crohn’s disease (CD) from other conditions (e.g., ulcerative colitis).
Ileocolonoscopy: Offers a detailed view of the terminal ileum and proximal colon, and can be used therapeutically (e.g., dilation of strictures):
Anatomical Structures Examined:
- Segmented discontinuities
- Natural folds
- Longitudinal lesions
- Penetrating ulcers
- Systemic signs such as inflamed sections identified by deeper ulcerations.
Esophagogastroduodenoscopy (EGD): Allows assessment of upper gastrointestinal involvement in patients showing relevant symptoms.
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Pathology
- Skip Lesions: Characterized by patchy, discontinuous inflammation in the bowel, with areas of healthy tissue interspersed.
- Creeping Fat: Indicative of underlying inflammation with infiltration of fat around the affected bowel segment.
- Hypertrophic Lymph Nodes: Enlarged lymph nodes associated with inflammatory processes.
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Differential Diagnoses
- Ulcerative Colitis
- Acute Appendicitis
- Infectious Gastroenteritis/Colitis
- Noninfectious Colitis: Such as radiation enteritis or colitis induced by medication.
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Complications
- Colorectal Cancer: Particularly linked to the disease’s duration and extent (especially in cases of pancolitis).
- Stricture Formation: Resulting in bowel obstruction.
- Peritonitis: May arise due to perforation.
- Cholangitis: Inflammation of the bile duct system.
- Impaired Bile Salt Reabsorption: Leading to malabsorption.
- Malabsorption Issues: Including steatorrhea and deficiencies in fat-soluble vitamins.
- Abscess Formation or Phlegmons: Occurring near the intestinal lumen and affecting surrounding tissues.
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Systemic Complications
- Symptoms of Malabsorption Syndrome:
- Weight loss
- Failure to thrive and growth failure in children
- Anemia (Iron Deficiency Anemia, IDA)
- Osteoporosis
- Amyloidosis: A condition characterized by the accumulation of amyloid proteins in various tissues.
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Treatment
Pharmacotherapy
- The management of Crohn’s disease (CD) follows a stepwise approach.
Surgery
- Minimally Invasive Resection: Aims to remove affected and nonfunctional intestinal loops while preserving as much length and function as possible.
- Indications for Surgery: Considered when medical therapy fails or when the patient develops complications such as obstruction, stricture, or abscess.
Methods
- Balloon Dilation: Used to treat intestinal strictures.
- Percutaneous Drainage: Helps prevent retention of secretions.
- Surgical Drainage: May be required in cases of percutaneous drainage failure.
- Strictureplasty: An option for localized strictures (e.g., during procotectomy) in cases of obstruction or strictures.
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Additional Considerations
Lifestyle Modifications
- Smoking Cessation: Important for disease management.
- Avoiding Certain Medications: Particularly non-steroidal anti-inflammatory drugs (NSAIDs).
- Managing Stress
Management of Complications and Comorbidities
- Malnutrition Syndrome: Ensure appropriate supplementation of vitamins, calories, protein, zinc, calcium, and iron.
- Bile Acid Diarrhea: Use of ion-exchange resins to bind bile acids (e.g., cholestyramine).
- Depression and Anxiety
Prevention of Malignancies
- Increased Cancer Risk: Individuals with CD may have a higher risk of cancers affecting the small intestine, colon, and lymphatics.
- Regular Colonoscopies: Recommended to minimize cancer risk.
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Prognosis
- Chronic Nature of CD: The disease is lifelong and currently not curable.
- Normal Life Expectancy: Patients can maintain a normal life with appropriate management.
- Surgical Intervention: 70-90% of patients will require surgery at some point in their lives.
