Epithelial misplacement in Peutz-Jeghers polyps. A diagnostic pitfall.

Area of Science:

• Gastroenterology
• Surgical Pathology
• Oncology

Background:

• Peutz-Jeghers syndrome is associated with an increased risk of gastrointestinal carcinoma.
• Histopathological interpretation of Peutz-Jeghers polyps has historically been challenging, leading to overdiagnosis of cancer.
• Controversy exists regarding the precise magnitude of cancer risk in Peutz-Jeghers polyps.

Purpose of the Study:

• To investigate the phenomenon of epithelial misplacement in Peutz-Jeghers polyps.
• To identify histological features that differentiate true adenocarcinoma from pseudoinvasion.
• To clarify the contribution of histopathological misinterpretation to reported cancer incidence in Peutz-Jeghers syndrome.

Main Methods:

• Retrospective review of 491 Peutz-Jeghers polyps from St. Mark's Hospital Pathology department records.
• Detailed histopathological examination focusing on small intestinal, gastric, and colonic polyps.
• Analysis of specific histological features to distinguish between true invasion and pseudoinvasion.

Main Results:

• Epithelial misplacement, mimicking adenocarcinoma, was identified in approximately 10% of small intestinal Peutz-Jeghers polyps.
• This 'pseudoinvasion' was not observed in polyps of the stomach or colon.
• Histological discriminators for pseudoinvasion included lack of cytological atypia, normal epithelial cell subtypes, brush border, hemosiderin deposition, and intramural mucinous cysts.

Conclusions:

• Epithelial misplacement in Peutz-Jeghers polyps can lead to overdiagnosis of gastrointestinal carcinoma.
• Recognizing pseudoinvasion is crucial for accurate cancer risk assessment in Peutz-Jeghers syndrome.
• Most gastrointestinal cancers in Peutz-Jeghers syndrome arise in the upper gastrointestinal tract.