Neuroendocrine Tumors of the Luminal Gastrointestinal Tract

Abstract

Context.-Neuroendocrine tumors (NETs) of the gastrointestinal tract have been recognized for more than a century. Despite histologic similarities between different sites in the tract, behavior varies between areas. All of these tumors have malignant potential, but determination of exact risk is difficult.Objectives.-To review the diagnosis of luminal gastrointestinal NETs, including a discussion of grading. Grading by mitotic index/activity, in conjunction with tumor size/ stage, has been found to be the strongest predictor of behavior.Data Sources.-Literature review of luminal gastrointestinal NETs was performed and the results summarized.Conclusions.-Our understanding of these lesions is incomplete and continues to evolve.

Algorithmic approach to neuroendocrine tumors in targeted biopsies: Practical applications of immunohistochemical markers

“…The intra-abdominal cavity is a common source of NETs, which can arise from the pancreas and various gastrointestinal sites. 1,7,17,[77][78][79] In particular, primary pancreatic NETs are important to recognize because they can be treated with newer therapy regimens (including sunitinib and everolimus) and are more sensitive to chemotherapy than NETs arising from other sites. 7,[80][81][82] Furthermore, midgut NETs may be amenable to octreotide therapy, with promising outcomes reported in a subset of patients with advanced disease.…”

“…Immunohistochemical positivity for xenin, a hormone peptide found in endocrine cells of the duodenum, may be helpful to support a duodenal origin; however, this marker is not available in the majority of laboratories. 1,78,110 Although PAX-8 is a nuclear transcription factor implicated in the development of the optic, thyroid, urinary, and reproductive systems, it has also been shown to have strong immunohistochemical expression in normal human islets and pancreatic NETs. 1,8,[111][112][113][114][115][116][117][118][119] However, it should be noted that these findings were primarily based on a commercially available polyclonal PAX-8 antibody that also identifies other members of the PAX family (including PAX-3, PAX-5, and PAX-6).…”

“…In a ISL‐1‐positive and PDX‐1‐positive WDNET, the distinction between a pancreatic versus a duodenal WDNET can be challenging. Immunohistochemical positivity for xenin, a hormone peptide found in endocrine cells of the duodenum, may be helpful to support a duodenal origin; however, this marker is not available in the majority of laboratories . Although PAX‐8 is a nuclear transcription factor implicated in the development of the optic, thyroid, urinary, and reproductive systems, it has also been shown to have strong immunohistochemical expression in normal human islets and pancreatic NETs .…”

Clinicopathologic study of neuroendocrine tumors of gastroenteropancreatic tract: a single institutional experience

“…The third type of gastric NET comprises of sporadic tumors and do not show any evidence of atrophy or hyperplasia. These tumors unlike the other two subtypes are more often large with a higher grade, and have a worse prognosis (8).…”

Duodenal Epithelial Polyps: A Clinicopathologic Review

“…Endoscopically, they appear as a white or yellow polyp-like lesion with central dimpling or ulceration. 71 They are often clinically ''silent'' tumors but hormonal expression can be identified by immunohistochemistry. Occasionally, they can be functional and associated with clinical syndromes due to hormone hypersecretion, such as the gastrinoma.…”