Insulinoma

Abstract

There are vast differences in terminology, classification and grading of gastrointestinal neuroendocrine tumours (NETs); mostly the organ or tissue of origin is considered for nomenclature and grading. GI-NETs are relatively rare, accounting for approximately 0.5 % of all human cancers. Embryologically NETs are divided into three categories as described by William and Sandler: Foregut carcinoids (lung, stomach, duodenum, upper jejenum and pancreas), midgut carcinoids (lower jejenum, ileum, appendix, caecum) and hindgut carcinoids (colon and rectum). GI-NETs are those arising at the oesophagus, stomach, bile ducts and gall bladder, duodenum, jejunum, appendix, colon and rectum. Oesophageal NETs are extremely rare. Gastric NETs are divided into four groups based on clinicopathological features as type 1, type 2, type 3 and type 4. This classification has also prognostic and management implications. Primary duodenal NETs account for less than 2 % of all gastrointestinal NETs. They are relatively benign lesions with slow growth pattern and low metastatic potential. The ileum and appendix are the most common sites of NETs in the West, while colorectal NETs are relatively more common in the East. As for the classification, management also depends on the primary site, grade and the stage of the disease. In localised disease, surgery is the mainstay of treatment. In symptomatic cases, somatostatin analogues are effective. Liver-directed therapies and systemic cytotoxic drugs and targeted agents can be used in selected cases.