• A benign or malignant neoplasm composed of cells of neuroendocrine origin. Representative examples include paraganglioma, carcinoid tumor, and neuroendocrine carcinoma.
  • A neoplasm composed of cells of neuroendocrine origin for which the malignancy status has not been established.
  • A tumor derived from cells that release a hormone in response to a signal from the nervous system. Some examples of neuroendocrine tumors are carcinoid tumors, islet cell tumors, medullary thyroid carcinoma, and pheochromocytoma. These tumors secrete hormones in excess, causing a variety of symptoms.
  • A tumor that forms from cells that release hormones in response to a signal from the nervous system. Some examples of neuroendocrine tumors are carcinoid tumors, islet cell tumors, medullary thyroid carcinomas, pheochromocytomas, and neuroendocrine carcinomas of the skin (merkel cell cancer). These tumors may secrete higher-than-normal amounts of hormones, which can cause many different symptoms.
  • Tumors whose cells possess secretory granules and originate from the neuroectoderm, i.e., the cells of the ectoblast or epiblast that program the neuroendocrine system. Common properties across most neuroendocrine tumors include ectopic hormone production (often via apud cells), the presence of tumor-associated antigens, and isozyme composition.