Pancreatic insulinomas are rare tumours of the islet cells of the pancreas, which account for the majority of functional neuroendocrine tumours of the pancreas. There is often a typical history of recurrent hypoglycaemic collapse and dizzy spells. Insulinomas are usually solitary, and the vast majority are intra-pancreatic in location. They are characteristically small with approximately 66% being less than 2cm at presentation. Insulinomas continue to pose a diagnostic challenge to physicians, surgeons and radiologists alike. The role of imaging is to detect and provide precise anatomical localization and staging of tumours prior to surgery. Due to their small size at clinical presentation, they are notoriously difficult to localize radiologically, and specifically designed protocols are necessary to aid detection. In this review, we describe the current "state of the art" imaging protocols that may be used in the preoperative localization of insulinomas.
"1) Insulinoma. Grossly, 40% of these tumors are < 1 cm, and 66% are < 1.5 cm . They present as encapsulated, firm, brown, nodules that are histologically composed of cords and nests of welldifferentiated β cells that do not differ from the normal islet cells. "
"Conventional imaging (CT or MRI) reliably detected the insulinoma in only two patients, whereas endosonography identified a possible lesion in four patients, in keeping with data in the literature (McAuley et al., 2005). In three patients, selective arterial stimulation and venous sampling was performed, with accurate localization in all (Christ et al., 2009). "
[Show abstract][Hide abstract] ABSTRACT: Peptide hormones of the glucagon-like peptide (GLP) family play an increasing clinical role, such as GLP-1 in diabetes therapy. Moreover, GLP receptors are overexpressed in various human tumor types and therefore represent molecular targets for important clinical applications. In particular, virtually all benign insulinomas highly overexpress GLP-1 receptors (GLP-1R). Targeting GLP-1R with the stable GLP-1 analogs (111)In-DOTA/DPTA-exendin-4 offers a new approach to successfully localize these small tumors. This non-invasive technique has the potential to replace the invasive localization of insulinomas by selective arterial stimulation and venous sampling. Malignant insulinomas, in contrast to their benign counterparts, express GLP-1R in only one-third of the cases, while they more often express the somatostatin type 2 receptors. Importantly, one of the two receptors appears to be always expressed in malignant insulinomas. The GLP-1R overexpression in selected cancers is worth to be kept in mind with regard to the increasing use of GLP-1 analogs for diabetes therapy. While the functional role of GLP-1R in neoplasia is not known yet, it may be safe to monitor patients undergoing GLP-1 therapy carefully.
Frontiers in Endocrinology 12/2012; 3:158. DOI:10.3389/fendo.2012.00158
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