GI Lymphoma is a cancer of lymphocytes (a type of white blood cell) that involves the gastrointestinal (GI) tract. It can arise in the stomach, small intestine, colon, or less commonly other digestive organs. The term is commonly used in gastroenterology, hematology/oncology, pathology, radiology, and GI surgery to describe and classify these tumors.

MALT Lymphoma is a type of lymphoma that arises from immune cells in mucosa-associated lymphoid tissue. It most often involves the stomach, but it can occur in other mucosal organs. In gastroenterology, it is commonly discussed when evaluating chronic gastritis and unusual gastric ulcers or thickened folds. It is typically considered an indolent (slow-growing) B-cell malignancy, but behavior varies by case.

Eosinophilic Gastroenteritis is an inflammatory condition where eosinophils build up in parts of the gastrointestinal (GI) tract. It is discussed in gastroenterology when unexplained abdominal symptoms are paired with tissue eosinophilia on biopsy. It most often involves the stomach and small intestine, but other GI segments can be affected. It is used clinically as a diagnosis after other causes of GI eosinophilia are considered and excluded.

Autoimmune Pancreatitis is a form of pancreatitis driven by immune-mediated inflammation rather than alcohol, gallstones, or infection. It can mimic pancreatic cancer because it may cause a pancreatic mass, duct narrowing, and jaundice. It is commonly discussed in gastroenterology, hepatology, radiology, pathology, and pancreatic surgery. It is important because it is often steroid-responsive and may involve other organs.