Definition/General
Introduction:
Ischemic colitis is acute or chronic inflammation resulting from inadequate blood supply to colon
Most common form of ischemic bowel disease
Typically affects watershed areas (splenic flexure, rectosigmoid)
Shows variable severity from mild inflammation to gangrene.
Origin:
Results from reduced mesenteric blood flow
Affects watershed zones with marginal circulation
Caused by systemic hypotension, thromboembolism, or local vascular disease
Shows reperfusion injury component
Elderly population most affected.
Classification:
Acute ischemic colitis: sudden onset, severe symptoms
Chronic ischemic colitis: recurrent episodes, stricture formation
Gangrenous type: full-thickness necrosis
Non-gangrenous type: mucosal/submucosal involvement
Transient type: reversible changes.
Epidemiology:
Peak incidence in elderly patients (>60 years)
Female predominance (2:1 ratio)
Most common ischemic GI condition
Increasing incidence with aging population
Comorbidities common (cardiovascular disease).
Clinical Features
Presentation:
Sudden onset abdominal pain (crampy, left-sided)
Bloody diarrhea (within 24 hours)
Urgency and tenesmus
Nausea and vomiting
Low-grade fever
Abdominal tenderness.
Symptoms:
Crampy left lower quadrant pain (80-90%)
Rectal bleeding (bloody stools)
Diarrhea (may be bloody)
Nausea (50% cases)
Vomiting (30% cases)
Constitutional symptoms.
Risk Factors:
Advanced age (>60 years)
Cardiovascular disease
Hypertension
Diabetes mellitus
Medications (digitalis, diuretics, NSAIDs)
Hypotension
Dehydration.
Screening:
CT scan (thumbprinting sign)
Colonoscopy (mucosal changes)
Plain radiography (pneumatosis, portal venous gas)
Angiography (rarely needed)
Clinical diagnosis often sufficient.
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Gross Description
Appearance:
Segmental involvement of colon
Mucosal edema and hemorrhage
Thumbprinting appearance (submucosal edema)
Pseudomembrane formation
Ulceration (severe cases)
Wall thickening.
Characteristics:
Hemorrhagic mucosa with submucosal edema
Sharp demarcation between normal and affected areas
Longitudinal ulcerations
Necrotic areas (severe cases)
Stricture formation (chronic cases).
Size Location:
Splenic flexure (40-50% cases)
Rectosigmoid junction (20-25%)
Left-sided colon predominance
Watershed areas preferentially affected
Segmental distribution
Skip lesions possible.
Multifocality:
Segmental involvement typical
Watershed zone predilection
Skip areas between involved segments
Bilateral involvement rare
Recurrence at same sites possible.
Microscopic Description
Histological Features:
Mucosal necrosis and ulceration
Submucosal edema and hemorrhage
Hyalinized stroma (characteristic)
Ghost epithelial cells
Acute inflammatory infiltrate
Vascular congestion.
Cellular Characteristics:
Surface epithelial loss
Ghost cells (nuclear pyknosis)
Neutrophilic infiltrate
Hemorrhage in lamina propria
Endothelial swelling
Capillary thrombosis.
Architectural Patterns:
Crypt destruction
Surface denudation
Pseudomembrane formation (fibrin, debris)
Hyalinized submucosal stroma
Vascular changes (thrombosis, congestion)
Regenerative changes (healing phase).
Grading Criteria:
Mild: mucosal edema, minimal necrosis
Moderate: mucosal ulceration, submucosal changes
Severe: transmural necrosis, perforation risk
Chronic: fibrosis, stricture formation.
Immunohistochemistry
Positive Markers:
Cytokeratin (surviving epithelium)
CD68 (macrophages)
CD31 (vascular endothelium)
Smooth muscle actin (vessel walls)
Fibrin (pseudomembranes).
Negative Markers:
CMV (excludes viral colitis)
HSV (excludes viral colitis)
Specific bacterial antigens
Malignancy markers
IBD-associated markers.
Diagnostic Utility:
Excludes infectious etiology
Confirms vascular pathology
Assesses extent of necrosis
Differentiates from IBD
Usually not required for diagnosis.
Molecular Subtypes:
Acute ischemic (neutrophil-predominant)
Chronic ischemic (fibroblast-rich)
Reperfusion injury (mixed inflammatory)
Thrombotic (microthrombi present).
Molecular/Genetic
Genetic Mutations:
No specific genetic mutations
Thrombophilia genes (Factor V Leiden, prothrombin)
Cardiovascular risk genes
Endothelial function genes
Acquired risk factors more important.
Molecular Markers:
Hypoxia-inducible factors (HIF-1α)
Vascular endothelial growth factor (VEGF)
Inflammatory mediators (IL-1β, TNF-α)
Tissue factor
Endothelin-1.
Prognostic Significance:
Age (older patients worse prognosis)
Extent of involvement
Presence of gangrene
Comorbidities (cardiovascular disease)
Response to conservative treatment.
Therapeutic Targets:
Supportive care (fluid resuscitation, antibiotics)
Treatment of underlying conditions
Avoid vasoconstrictors
Surgical resection (gangrene, perforation)
Anticoagulation (selected cases).
Differential Diagnosis
Similar Entities:
Inflammatory bowel disease (Crohn, ulcerative colitis)
Infectious colitis (bacterial, viral)
Pseudomembranous colitis (C
difficile)
Drug-induced colitis
Radiation colitis.
Distinguishing Features:
Ischemic colitis: Segmental, watershed zones, hyalinized stroma
IBD: Continuous/skip, young age, chronic changes
Infectious: Organisms identified
C
difficile: Pseudomembranes, antibiotic history
Drug-induced: Medication history.
Diagnostic Challenges:
Distinguishing from IBD (age and location helpful)
Differentiating from infectious colitis
Recognizing chronic ischemic changes
Assessing severity and reversibility
Clinical correlation essential.
Rare Variants:
Chronic ischemic colitis (stricture formation)
Right-sided ischemic colitis (uncommon)
Nonocclusive mesenteric ischemia
Cocaine-induced ischemic colitis
Exercise-induced ischemic colitis.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
[specimen type] from [anatomical location]
Clinical Information
Clinical presentation: [symptoms]. Risk factors: [age, cardiovascular disease, etc.]
Location
Involvement of [specific colonic segment]. Watershed zone: [involved/spared]
Ischemic Features
Mucosal necrosis: [present/absent]. Ghost cells: [present/absent]. Hyalinized stroma: [present/absent]
Vascular Changes
Vascular congestion: [present/absent]. Microthrombi: [present/absent]. Endothelial changes: [present/absent]
Severity Assessment
Severity: [Mild/Moderate/Severe]. Transmural involvement: [present/absent]
Complications
Perforation: [present/absent]. Stricture formation: [present/absent]
Final Diagnosis
[Acute/Chronic] Ischemic Colitis, [mild/moderate/severe]