Gastrinomas are rare tumors that typically develop in the pancreas or the duodenum (the first part of the small intestine). These tumors produce excessive amounts of the hormone gastrin, which stimulates the stomach to produce acid. This can lead to the development of peptic ulcers, diarrhea, and other symptoms associated with a condition known as Zollinger-Ellison syndrome. Gastrinomas are usually considered to be a type of neuroendocrine tumor and can be either benign or malignant. They are often diagnosed through blood tests to measure gastrin levels, imaging studies such as CT or MRI scans, and sometimes endoscopic procedures to visualize the tumor. Treatment options for gastrinomas may include surgery to remove the tumor, medications to control acid production, and other therapies to manage symptoms and prevent complications.