Pathology of gastrointestinal disorders

Area of Science:

• Gastroenterology
• Endocrinology
• Oncology

Background:

• Gastrointestinal endocrine cells can develop nonneoplastic and neoplastic proliferative lesions.
• Understanding these lesions is crucial for diagnosis and treatment.
• Existing literature lacks systematic definitions for some gastrointestinal endocrine cell lesions.

Purpose of the Study:

• To detail nonneoplastic and neoplastic proliferative lesions of gastrointestinal endocrine cells.
• To identify the continuum from hyperplasia to neoplasia in specific cell types.
• To describe the characteristics and prevalence of neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs) in different gastrointestinal segments.

Main Methods:

• Review and synthesis of existing literature on gastrointestinal endocrine cell lesions.
• Identification of multistep continua from hyperplasia to neoplasia.
• Classification and description of NETs and NECs based on cell type, location, and clinical behavior.

Main Results:

• A continuum from hyperplasia to neoplasia is identified for gastric histamine-producing enterochromaffin-like (ECL) cells.
• Gastric NETs are often silent ECL cell tumors; high-grade NECs are the second most frequent.
• Duodenal gastrin (G)-cell NETs are most common, followed by somatostatin (D)-cell NETs and gangliocytic paraganglioma (GCP).
• Ileal NETs are typically serotonin-producing enterochromaffin (EC)-cell NETs (carcinoid), with functional syndromes rare unless liver metastases are present.
• Colorectal NECs are aggressive, often with mixed components and poor outcomes.

Conclusions:

• Gastrointestinal endocrine cell lesions exhibit diverse pathological pathways and clinical presentations.
• Gastric and duodenal NETs have distinct cell origins and frequencies.
• Colorectal NECs represent a distinct, aggressive entity requiring specific management strategies.