Definition/General
Introduction:
Small intestinal inflammatory polyps are reactive lesions composed of granulation tissue and inflammatory cells
They are non-neoplastic proliferative responses to chronic inflammation
They commonly occur in inflammatory bowel disease
They are also called pseudopolyps or inflammatory pseudopolyps.
Origin:
Results from chronic mucosal inflammation
Granulation tissue response to injury
Reactive epithelial proliferation
Associated with Crohn disease, ulcerative colitis, infections
Healing response to mucosal ulceration.
Classification:
Based on etiology: IBD-associated (most common)
Infectious (bacterial, parasitic)
Ischemic
Drug-induced
Based on morphology: filiform polyps
Sessile inflammatory polyps
Giant inflammatory polyps.
Epidemiology:
Common in IBD patients (10-20%)
Equal gender distribution
Any age group
Associated with disease activity
More common in Crohn disease than UC.
Clinical Features
Presentation:
Often asymptomatic
Associated with underlying IBD symptoms
Diarrhea and abdominal pain
Rectal bleeding
Intestinal obstruction (large polyps)
Protein-losing enteropathy (extensive polyposis).
Symptoms:
Crampy abdominal pain
Chronic diarrhea
Blood and mucus in stool
Weight loss
Fatigue
Signs of IBD activity
Intestinal obstruction (rare).
Risk Factors:
Inflammatory bowel disease
Chronic infections
Ischemic colitis
Medication-induced inflammation
Previous surgery
Chronic irritation.
Screening:
Colonoscopy with biopsy
Small bowel imaging (CT enterography)
Capsule endoscopy
Histopathological examination
IBD activity assessment.
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Gross Description
Appearance:
Filiform or finger-like projections
Edematous and erythematous
Soft, friable consistency
Variable size (few mm to several cm)
Multiple polyps common
Surface ulceration possible.
Characteristics:
Irregular surface
Pedunculated or sessile
Red or pink coloration
Easily traumatized
Associated mucosal inflammation
May be numerous.
Size Location:
Terminal ileum and right colon most common
Throughout small bowel in Crohn disease
Size: 0.2-5 cm
Multiple distribution
Associated with inflamed mucosa.
Multifocality:
Multiple polyps common
Clustered distribution
Associated with active inflammation
Skip lesions in Crohn disease
Diffuse involvement possible.
Microscopic Description
Histological Features:
Granulation tissue with capillaries and fibroblasts
Chronic inflammatory infiltrate
Surface epithelial hyperplasia
Edematous stroma
Ulceration and regenerative changes
No dysplasia.
Cellular Characteristics:
Proliferating capillaries
Fibroblasts and myofibroblasts
Chronic inflammatory cells: lymphocytes, plasma cells, eosinophils
Neutrophils (active inflammation)
Reactive epithelium.
Architectural Patterns:
Granulation tissue core
Surface epithelial covering
Irregular glandular pattern
Stromal edema
Vascular proliferation
Fibrosis (chronic cases).
Grading Criteria:
Activity assessment: acute vs chronic inflammation
Epithelial changes: reactive vs dysplastic
Stromal composition: granulation tissue vs fibrosis
Ulceration presence.
Immunohistochemistry
Positive Markers:
CD68 (macrophages)
CD31 (endothelial cells)
SMA (myofibroblasts)
Ki-67 (proliferating cells)
Cytokeratins (epithelium).
Negative Markers:
p53 (no dysplasia)
CDX2 (may be weak)
Chromogranin A (no neuroendocrine cells)
S-100 (no nerve involvement).
Diagnostic Utility:
Confirms inflammatory nature
Demonstrates reactive changes
Excludes dysplasia
Identifies cell types in inflammatory infiltrate
Assesses proliferative activity.
Molecular Subtypes:
IBD-associated: Th1/Th17 inflammatory pattern
Infectious: neutrophil-predominant
Ischemic: surface necrosis pattern.
Molecular/Genetic
Genetic Mutations:
No specific mutations
Reactive genetic changes
Cytokine gene expression
Growth factor upregulation
Tissue repair pathways activated.
Molecular Markers:
Inflammatory cytokines: TNF-α, IL-1β, IL-6
Growth factors: VEGF, PDGF, TGF-β
Angiogenesis markers
Tissue remodeling markers.
Prognostic Significance:
Benign lesions
Regression possible with IBD treatment
No malignant potential
May cause obstruction if large
Recurrence with disease activity.
Therapeutic Targets:
Treat underlying IBD
Anti-inflammatory therapy
Polypectomy (symptomatic polyps)
Immunosuppressive therapy
Supportive care.
Differential Diagnosis
Similar Entities:
Adenomatous polyp
Juvenile polyp
Peutz-Jeghers polyp
Hyperplastic polyp
Carcinoid tumor
Lymphoid polyp.
Distinguishing Features:
Inflammatory polyp: granulation tissue, no dysplasia, IBD association
Adenoma: dysplastic epithelium
Juvenile: cystic glands
PJ: smooth muscle core
Hyperplastic: serrated architecture.
Diagnostic Challenges:
Distinguishing from adenomatous polyps
Recognizing reactive atypia vs dysplasia
Identifying underlying cause
Correlation with clinical history
Adequate tissue sampling.
Rare Variants:
Giant inflammatory polyps
Filiform polyposis
Inflammatory cap polyps
Granulomatous polyps
Post-surgical inflammatory polyps.
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
Small bowel polyp(s), [number] fragments, [size] cm
Diagnosis
Inflammatory polyp(s)
Histological Features
Polyp composed of granulation tissue with chronic inflammation and reactive epithelium
Granulation Tissue
Proliferating capillaries, fibroblasts, and chronic inflammatory cells
Epithelial Changes
Reactive epithelial hyperplasia without dysplasia
Inflammatory Pattern
Chronic inflammation with [lymphocytes/plasma cells/eosinophils]
Dysplasia
No dysplastic changes identified
Special Studies
Ki-67: [low proliferation], p53: [negative]
Clinical correlation with IBD status recommended
[other study]: [result]
Recommendations
Clinical correlation with underlying inflammatory bowel disease
Final Diagnosis
Small intestinal inflammatory polyp(s), benign