Neuroendocrine cell micronests of the colon

Abstract

Neuroendocrine cell micronests (NCMs) is a rare, microscopic entity comprised of small clusters of neuroendocrine cells in the mucosa which can arise throughout the luminal gastrointestinal system. Known by many names such as “microcarcinoids” and “neuroendocrine dysplasia,” NCMs are underdiagnosed, in part, due to lack of consensus on nomenclature. Recent studies suggest shared pathogenesis between NCMs and squamous morules/metaplasia. NCMs may appear at the base of adenomas, in inflammatory bowel disease, and in the defunctioned bowel. Several hypotheses for the pathogenesis of NCMs have been proposed, involving an interplay of both chronic mucosal damage and the altered Wnt/beta-catenin pathway. NCMs of the colon have an indolent behavior with most patients simply requiring repeat colonoscopy or polypectomy when they are at the base of an adenoma. Misdiagnosis is possible due to under-recognition, however a panel of immunohistochemical stains has proven useful in diagnostically challenging cases.

Keywords

• Colon
• Neuroendocrine
• Micronests
• Microcarcinoid
• Composite intestinal adenoma-microcarcinoid
• Inflammatory bowel disease