Definition/General
Introduction:
Peutz-Jeghers polyp is a distinctive hamartomatous polyp characterized by arborizing smooth muscle bands
Pathognomonic feature of Peutz-Jeghers syndrome
Shows smooth muscle proliferation extending into polyp head
Increased cancer risk in syndromic setting.
Origin:
Arises from developmental abnormality of muscularis mucosae
Results from smooth muscle hyperplasia and extension
Shows hamartomatous growth pattern
Associated with STK11/LKB1 gene mutations
Represents disorganized tissue growth.
Classification:
Classified as hamartomatous polyp
Peutz-Jeghers syndrome (multiple polyps with mucocutaneous pigmentation)
Isolated Peutz-Jeghers polyp (rare, sporadic)
Part of hamartomatous polyp spectrum
WHO recognizes as distinct entity.
Epidemiology:
Peak incidence in second to third decades
Equal gender distribution
Autosomal dominant inheritance (Peutz-Jeghers syndrome)
Small bowel most common site overall
Colorectal involvement in 60% of PJS patients
Rare in Indian population but increasingly recognized.
Clinical Features
Presentation:
Abdominal pain (cramping, intermittent)
Intussusception (small bowel polyps)
Gastrointestinal bleeding
Mucocutaneous pigmentation (lips, buccal mucosa)
Bowel obstruction
Rectal bleeding (colorectal polyps).
Symptoms:
Colicky abdominal pain (most common)
Nausea and vomiting (obstruction)
Melena (upper GI bleeding)
Bright red bleeding (colorectal)
Iron deficiency anemia
Perioral pigmentation.
Risk Factors:
STK11/LKB1 mutations (Peutz-Jeghers syndrome)
Family history of PJS
Mucocutaneous pigmentation
Previous GI polyps
Genetic predisposition
Autosomal dominant inheritance.
Screening:
Upper and lower endoscopy
Capsule endoscopy (small bowel)
Magnetic resonance enterography
Genetic testing (STK11/LKB1)
Family screening
Cancer surveillance (multiple organs).
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Gross Description
Appearance:
Pedunculated polyp with lobulated surface
Tan to pink coloration
Multilobular contour
Firm consistency
Smooth surface
Well-demarcated head and stalk.
Characteristics:
Cerebriform or brain-like surface
Multiple lobules separated by clefts
Cut surface shows white streaks (smooth muscle)
Solid consistency
No surface ulceration (unless traumatized)
Complex architecture visible.
Size Location:
Size ranges from 0.5-5 cm
Colorectal polyps typically smaller than small bowel
Rectosigmoid most common colorectal site
Pan-colonic distribution possible
Small bowel (jejunum most common overall).
Multifocality:
Multiple polyps (Peutz-Jeghers syndrome)
Pan-gastrointestinal involvement
Small bowel predominance
Gastric polyps (fundic gland type)
Colonic polyps less frequent but important.
Microscopic Description
Histological Features:
Arborizing smooth muscle bands (pathognomonic)
Normal epithelium covering polyp surface
Smooth muscle extending into polyp head
Lamina propria between muscle bands
No dysplastic changes
Complex branching pattern.
Cellular Characteristics:
Normal colonic epithelium
Mature goblet cells
Surface epithelial cells normal
Smooth muscle cells in bands
No cytologic atypia
Normal proliferation pattern.
Architectural Patterns:
Tree-like smooth muscle bands
Epithelium draped over muscle framework
Branching and anastomosing muscle bands
Complex lobular architecture
Muscularis mucosae extension
Hamartomatous organization.
Grading Criteria:
No grading system (benign lesion)
Assessment for dysplasia (usually absent)
Pseudoinvasion (epithelium in submucosa)
Misplaced epithelium should not be mistaken for carcinoma
Inflammation minimal unless traumatized.
Immunohistochemistry
Positive Markers:
Smooth muscle actin (muscle bands)
Caldesmon (smooth muscle)
CDX2 (epithelium)
CK20 (colonocytes)
Desmin (smooth muscle).
Negative Markers:
CK7 (epithelium usually negative)
p53 (wild-type pattern)
β-catenin (membranous staining)
Chromogranin A (unless neuroendocrine cells)
CD34 (negative in muscle).
Diagnostic Utility:
Smooth muscle actin highlights characteristic bands
Caldesmon positivity confirms smooth muscle
CDX2 confirms colonic epithelium
Normal proliferation markers
Immunohistochemistry rarely needed (characteristic morphology).
Molecular Subtypes:
STK11/LKB1-associated (Peutz-Jeghers syndrome)
Sporadic cases (extremely rare)
Germline mutations (most cases)
Somatic mutations (rare)
mTOR pathway involvement.
Molecular/Genetic
Genetic Mutations:
STK11/LKB1 mutations (95% of PJS cases)
Germline mutations (hereditary)
Large deletions (some cases)
Nonsense mutations (common)
Frameshift mutations.
Molecular Markers:
LKB1 tumor suppressor loss of function
mTOR pathway activation
AMPK signaling disruption
p53 pathway intact
Normal DNA mismatch repair.
Prognostic Significance:
Increased cancer risk (PJS syndrome)
Cumulative cancer risk 90% by age 65
GI cancers most common
Breast cancer risk (women)
Regular surveillance essential.
Therapeutic Targets:
Polypectomy (symptomatic polyps)
Surgical resection (large polyps, intussusception)
Surveillance endoscopy
Cancer screening (multiple organs)
Genetic counseling essential.
Differential Diagnosis
Similar Entities:
Juvenile polyp (cystic glands)
Inflammatory polyp (granulation tissue)
Adenomatous polyp (dysplastic epithelium)
Lipomatous polyp (mature adipose tissue)
Inflammatory fibroid polyp.
Distinguishing Features:
Peutz-Jeghers polyp: Arborizing smooth muscle bands
Juvenile polyp: Cystic glands, inflammatory stroma
Inflammatory polyp: Granulation tissue
Adenoma: Dysplastic epithelium
Lipoma: Mature fat.
Diagnostic Challenges:
Distinguishing from juvenile polyps (smooth muscle vs cystic)
Recognizing pseudoinvasion (not malignancy)
Identifying syndromic association
Assessing for dysplastic transformation (rare)
Adequate sampling important.
Rare Variants:
Peutz-Jeghers polyp with dysplasia (rare)
Atypical Peutz-Jeghers polyp
Mixed hamartomatous polyp
Peutz-Jeghers-like polyp (without syndrome)
Adenomatous transformation (very rare).
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], measuring [size] cm in greatest dimension
Diagnosis
Peutz-Jeghers Polyp
Location
Location: [anatomical site in GI tract]
Architectural Features
Shows characteristic arborizing smooth muscle bands extending into polyp head. Tree-like branching pattern of smooth muscle present.
Epithelial Features
Surface epithelium appears normal without dysplastic changes. Epithelium draped over smooth muscle framework.
Smooth Muscle Component
Prominent smooth muscle bands with arborizing, tree-like configuration characteristic of Peutz-Jeghers polyp
Dysplasia Assessment
No dysplastic changes identified. Normal epithelial maturation present.
Excision Status
Complete excision: [achieved/not achieved]
Final Diagnosis
Peutz-Jeghers Polyp - Hamartomatous polyp with characteristic smooth muscle bands