gastrinomas arises from g cell which are present in stomach then how the most commonly site for gastrinomas are duodenum and how they can be present in pancreas because g cells are present in stomach how they arise in duodenum and pancreas?
gastrinomas typically arise from G cells, which are predominantly found in the stomach. Gastrinomas are neuroendocrine tumors that produce excessive amounts of gastrin, a hormone that stimulates the release of gastric acid.
While the majority of gastrinomas arise from G cells in the stomach (known as gastric gastrinomas), approximately 25-30% of gastrinomas occur outside the stomach, most commonly in the duodenum (known as duodenal gastrinomas). The presence of gastrin-secreting cells in the duodenum allows for the development of duodenal gastrinomas.
The exact mechanism by which gastrinomas develop in the duodenum is not fully understood. It is believed that during embryonic development, precursor cells that have the potential to differentiate into G cells can migrate from the stomach to the duodenum. These precursor cells can then undergo abnormal growth and transform into gastrin-secreting tumor cells, resulting in duodenal gastrinomas.
Regarding the presence of gastrinomas in the pancreas, it is important to note that the pancreas contains a small number of scattered G cells, although they are not as abundant as those in the stomach. In some cases, gastrinomas can arise from these scattered G cells in the pancreas (known as pancreatic gastrinomas). The exact reasons for the development of pancreatic gastrinomas are not entirely clear, but it is believed to involve similar mechanisms as duodenal gastrinomas, such as migration and abnormal growth of precursor cells.
In summary, while G cells are primarily located in the stomach, gastrinomas can develop outside the stomach, particularly in the duodenum and, less commonly, in the pancreas. The presence of scattered G cells in the duodenum and pancreas, as well as the migration and abnormal growth of precursor cells, contribute to the development of gastrinomas in these locations.