Small Bowel Epithelial Precursor Lesions: A Focus on Molecular Alterations.

Area of Science:

• Gastroenterology and Pathology
• Oncology
• Genetics

Background:

• Gastrointestinal endoscopic procedures have increased the detection of small intestinal preneoplastic and neoplastic epithelial lesions.
• These lesions, primarily in the duodenum and ampulla, can be sporadic or linked to hereditary tumor syndromes.
• Dysplastic lesions are also found adjacent to small bowel adenocarcinomas in inflammatory conditions like celiac and Crohn's disease.

Purpose of the Study:

• To provide a comprehensive review of the histo-molecular features of small bowel epithelial precursor lesions.
• To categorize and describe various types of these precursor lesions, including sporadic, syndromic, and those associated with inflammatory diseases.

Main Methods:

• Literature review focusing on histo-molecular characteristics of small bowel epithelial precursors.
• Categorization of lesions including sporadic adenomas, syndromic adenomas, dysplasia in inflammatory conditions, serrated lesions, hamartomas, and neuroendocrine precursors.

Main Results:

• Small intestinal adenomas can show intestinal-type, gastric-type, or serrated differentiation, linked to distinct molecular pathways.
• Hereditary syndromes like FAP, MYH-AP, Lynch, Peutz-Jeghers, JPS, and Cowden syndrome are associated with these precursor lesions.
• Dysplasia in celiac and Crohn's disease, and precursor neuroendocrine growths in MEN1 syndrome are also significant findings.

Conclusions:

• A thorough understanding of small bowel epithelial precursor lesions is crucial for early detection and management.
• The diverse origins and molecular mechanisms of these lesions necessitate a comprehensive diagnostic approach.
• This review consolidates knowledge on various precursor lesions, aiding in clinical and research advancements.