[Neuroendocrine tumors of the gastrointestinal tract]

The diffuse neuroendocrine cell system of the gastrointestinal tract gives rise to the neuroendocrine neoplasms. The WHO classification distinguishes between well differentiated neuroendocrine tumors of benign or uncertain behavior, well differentiated neuroendocrine carcinomas of low grade malignancy and poorly differentiated neuroendocrine carcinomas of high grade malignancy. The well differentiated neuroendocrine tumors and carcinomas correspond to the carcinoids of earlier classifications. Further biological and prognostic classification of these neoplasms must consider the localization of the tumors within the gastrointestinal tract. This system allows a clinically relevant diagnosis and includes all so far known tumor entities.