Definition/General
Introduction:
Juvenile polyps are hamartomatous polyps characterized by cystically dilated glands and inflammatory stroma
They are benign lesions most common in children
They show normal epithelium without dysplasia
They can be sporadic or part of juvenile polyposis syndrome.
Origin:
Results from hamartomatous proliferation
Inflammatory response leads to stromal expansion
Cystic glandular dilatation develops
Surface ulceration common due to trauma
SMAD4 or BMPR1A mutations in syndromic cases.
Classification:
Sporadic juvenile polyps: isolated lesions
Juvenile polyposis syndrome: multiple polyps
Infantile type: smooth surface
Adult type: lobulated surface
Based on location: colonic (90%), small bowel (10%).
Epidemiology:
Most common polyp in children
Peak incidence: 2-10 years
Slight male predominance
Rectosigmoid most common location
Small bowel involvement rare (5-10% cases).
Clinical Features
Presentation:
Rectal bleeding (most common)
Polyp prolapse through rectum
Abdominal pain
Intussusception (small bowel polyps)
Iron deficiency anemia
Usually asymptomatic (small polyps).
Symptoms:
Painless rectal bleeding
Mucus discharge
Tenesmus
Change in bowel habits
Abdominal cramping
Prolapsing mass (large polyps).
Risk Factors:
Young age (childhood)
Family history (juvenile polyposis syndrome)
SMAD4 mutations
BMPR1A mutations
ENG mutations (hereditary hemorrhagic telangiectasia overlap).
Screening:
Colonoscopy (if symptomatic)
Genetic testing (multiple polyps)
Family screening (syndromic cases)
Upper endoscopy (small bowel polyps)
Capsule endoscopy.
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Gross Description
Appearance:
Pedunculated polyps with smooth surface
Cherry-red coloration
Soft, friable consistency
Surface ulceration common
Lobulated contour
Size varies (0.5-3 cm).
Characteristics:
Rounded, smooth surface
Pedunculated attachment
Granular appearance
Hemorrhagic surface
Easily traumatized
Non-neoplastic appearance.
Size Location:
Small bowel involvement uncommon
Duodenum occasionally
Jejunum and ileum rare
Size: 0.5-3 cm typically
Usually solitary in small bowel.
Multifocality:
Solitary polyps (sporadic cases)
Multiple polyps (juvenile polyposis syndrome)
Concurrent colonic polyps common
Gastric polyps in syndromic cases.
Microscopic Description
Histological Features:
Cystically dilated glands filled with mucin
Inflamed fibrous stroma
Surface epithelial ulceration
Chronic inflammation
Granulation tissue
Normal epithelium (no dysplasia).
Cellular Characteristics:
Normal columnar epithelium
Goblet cells preserved
Inflammatory cells: lymphocytes, plasma cells, eosinophils
Fibroblasts and endothelial cells
Smooth muscle fibers (minimal).
Architectural Patterns:
Cystic glandular dilatation
Branching gland pattern
Stromal expansion with inflammation
Surface erosion and ulceration
Edematous stroma
Vascular congestion.
Grading Criteria:
No grading system (benign hamartomas)
Surface ulceration assessment
Degree of inflammation
Epithelial regeneration
Presence of dysplasia (rare, suggests malignant transformation).
Immunohistochemistry
Positive Markers:
CK20 (surface epithelium)
CDX2 (intestinal differentiation)
MUC2 (goblet cells)
Ki-67 (low proliferation)
Smooth muscle actin (stromal smooth muscle).
Negative Markers:
p53 (usually negative)
β-catenin (membranous pattern)
MLH1, MSH2 (retained expression)
Chromogranin A (no neuroendocrine cells).
Diagnostic Utility:
Confirms intestinal epithelial origin
Demonstrates lack of dysplasia
Excludes adenomatous polyps
Assesses proliferative activity
Evaluates mismatch repair proteins (syndromic cases).
Molecular Subtypes:
Sporadic juvenile polyps: normal markers
Juvenile polyposis syndrome: SMAD4/BMPR1A loss
HHT-JPS overlap: ENG mutations.
Molecular/Genetic
Genetic Mutations:
SMAD4 mutations (50-60% of JPS)
BMPR1A mutations (20-25% of JPS)
ENG mutations (rare, HHT overlap)
PTEN mutations (PTEN hamartoma syndrome)
10q23 deletions.
Molecular Markers:
TGF-β pathway disruption
BMP signaling abnormalities
Loss of growth suppression
PTEN/PI3K pathway (some cases)
Angiogenesis factors.
Prognostic Significance:
Sporadic polyps: excellent prognosis
Juvenile polyposis syndrome: increased cancer risk (50% lifetime risk)
Early onset: higher cancer risk
Family history: genetic counseling needed.
Therapeutic Targets:
Polypectomy: curative for sporadic polyps
Surveillance endoscopy: syndromic cases
Prophylactic surgery: extensive polyposis
Genetic counseling
Family screening.
Differential Diagnosis
Similar Entities:
Peutz-Jeghers polyp
Inflammatory polyp
Adenomatous polyp
Hyperplastic polyp
Inflammatory bowel disease polyp
Retention polyp.
Distinguishing Features:
Juvenile polyp: cystic glands, inflammatory stroma
PJ polyp: smooth muscle core
Adenoma: dysplastic epithelium
Hyperplastic: serrated architecture
IBD polyp: background colitis.
Diagnostic Challenges:
Distinguishing from inflammatory polyps
Recognizing syndromic cases
Excluding dysplastic changes
Identifying surface ulceration
Correlation with clinical presentation.
Rare Variants:
Atypical juvenile polyps
Juvenile polyps with dysplasia
Mixed hamartomatous polyps
Giant juvenile polyps
Juvenile polyposis coli.
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, [size] cm, [pedunculated/sessile]
Diagnosis
Juvenile (hamartomatous) polyp
Histological Features
Hamartomatous polyp with cystic glandular dilatation and inflammatory stroma
Glandular Features
Cystically dilated glands filled with mucin and lined by normal epithelium
Stromal Features
Inflamed fibrous stroma with chronic inflammatory infiltrate
Epithelial Changes
Surface epithelium shows [intact/ulcerated] with no dysplasia
Dysplasia
No dysplastic changes identified
Special Studies
CDX2: positive (intestinal epithelium), Ki-67: low proliferation index
Genetic testing: [recommended if multiple polyps]
[other study]: [result]
Recommendations
Clinical correlation, consider genetic evaluation if multiple polyps or family history
Final Diagnosis
Small intestinal juvenile (hamartomatous) polyp without dysplasia