Pathology of neuro-endocrine tumours

Neuroendocrine tumours are defined by a common phenotype,which is not supported by a common embryologic origin. This commonphenotype is characterized by the expression of general neuroendocrinemarkers and sometimes by cell specific hormonal products.Neuroendocrine tumours are ubiquitous, but the major localizationsare the digestive tract and the pancreas. According to theWHO classification of lung tumours, they are divided in low gradeand high grade tumours. Since most digestive and pancreatic tumoursare low grade tumours, a specific classification of neuroendocrinetumours was recently proposed by the WHO. Size, degreeof invasion, major secretion and proliferation rate are the main criteriaof this classification. Most neuroendocrine tumours are sporadic.A few cases occur in the context of a multiple endocrine neoplasiatype 1.