The subject of neuroendocrine neoplasms, starting with the definition of what neuroendocrine means, is thoroughly confusing to the beginner. This chapter reviews the basic concepts and definitions pertaining to this subject.
Let us start with a definition of neuroendocrine. As the term implies, there are two components: “neuro” and “endocrine.” The “endocrine” quality refers to the secretory nature of neuroendocrine cells: they produce and secrete peptides and amines. The “neuro” quality refers to their ultrastructural similarity to neurons: neuroendocrine cells store their secretory products in granules (i.e., dense-core granules), which bear resemblance to synaptic vesicles. Neuroendocrine cells are different from neurons structurally (no processes) and by the fact that the secretory mode is paracrine rather than synaptic. Also note that not all that secretes is neuroendocrine: for example, thyroid and adrenal cortex are not neuroendocrine because their cells do not possess neurosecretory granules (they are simply endocrine). Thus, at the most basic level, neuroendocrine cells are defined as the presence of neurosecretory granules in nonneurons. Tumors derived from these cells have a characteristic “neuroendocrine morphology” and share expression of “neuroendocrine markers.”
KeywordsCarcinoid Tumor Small Cell Carcinoma Neuroendocrine Carcinoma Merkel Cell Carcinoma Islet Cell Tumor
Unable to display preview. Download preview PDF.