Klin Onkol 2018; 31(3): 167. DOI: 10.14735/amko2018167.
Background: Tumors aris ing from neuroendocrine cells are defi ned as epithelial neoplasms with predominantly neuroendocrine diff erentiation.
They comprise a distinct group of tumors with a characteristic histological structure and functional properties that develop at various sites, particularly the gastrointestinal system (67%) and lungs (25%). Although such tumors are usually slow-grow ing and indolent, almost all have malignant
potential and most can produce active hormones. Clinical signs vary, and many are dependent on the site at which the tumor develops. Although these tumors were identifi ed more than 130 years, their classifi cation remains unclear. Purpose: This review provides a comprehensive overview of the human neuroendocrine system and its neoplasms, from their discovery to current terminology and classifi cations. In addition, the clinical symp tomatology and macroscopic/ microscopic features of tumors aris ing from endocrine cells of the gastrointestinal tract are described, with an emphasis on their classifi cation, dia gnostic criteria for their grad ing and TNM (tumor, node, metastasis) staging, and how these tumors diff er accord ing to their localization in the gastrointestinal tract . Conclusion: Tumors aris ing from neuroendocrine cells are rare and can cause typical symp toms of carcinoid syndrome. However, most of these tumors are asymp tomatic, which, together with their typical small size and localization in the gut, makes them diffi cult to access endoscopically and often leads to dia gnosis at an advanced stage. To success fully diagnose and treat tumors aris ing from neuroendocrine cells, they should be assessed us ing a diff erential dia gnostic procedure and be histopathologically classifi ed, graded, and staged accord ing to specifi ed criteria and the latest classifi cations and guidelines. Although the terms “carcinoid”,“neuroendocrine tumor”, and “neuroendocrine carcinoma” are often used synonymously in the literature and by professionals, more precise terminology is required for nomenclature and classifi cation.
