Poorly differentiated neuroendocrine carcinoma

Poorly differentiated endocrine neoplasms, depending on the site of origin, may produce characteristic peptide hormones. The group of poorly differentiated neuroendocrine tumors and their hormone production include islet cell tumors (insulin, glucagon, somatostatin, gastrin), pulmonary small cell carcinoma (bombesin in 45% of cases), and medullary thyroid carcinoma (calcitonin). 

HIGH-GRADE (POORLY DIFFERENTIATED) NEUROENDOCRINE CARCINOMAS... 

High-grade, poorly differentiated neuroendocrine carcinomas of the duodenum occur primarily in the region of the papilla of Vater and are covered in detail in Chapter 15. 

These highly aggressive and rapidly fatal tumors constitute less than 1% of all pancreatic endocrine neoplasms. They are so uncommon that some authors believe a poorly differentiated neuroendocrine carcinoma occurring in the pancreas is most likely a metastasis from an occult primary in the lung. However, there are proven cases of primary in this region." " Many are in fact of ampullary origin, and few are pancreatic. 

Kaifi JT, Heidtmann S, Schurr PG, et al. Absence of LI in pancreatic masses distinguishes adenocarcinomas from poorly differentiated neuroendocrine carcinomas. Anticancer Res. 2006 26 1167-1170. 

CK8 +, CK18 +, CK19 +, Chromogranin +, NSE +, PGP9.5 +, Synaptophysin +, Leu7 +, SlOO +/—, CK5/6 -, CK7 -, CK20 -Proliferation index [Ki-67 (MIB-1) index] in well differentiated neuroendocrine tumor <2% Proliferation index [Ki-67 (MIB-1) index] in well differentiated neuroendocrine carcinoma >2% Proliferation index ] Ki-67 (MIB-1) index] in poorly differentiated neuroendocrine carcinoma >30% Insulin +, Proinsulin +... 

FIGURE 11.16 Markers of interest in the differential diagnosis between poorly differentiated adenocarcinoma (ADCA) and neuroendocrine carcinoma of the mediastinum (NEQ. 

Visscher DW, Zarbo RJ, Trojanowski JQ, et al. Neuroendocrine differentiation in poorly-differentiated lung carcinomas A light microscopic and immunohistochemical study. Mod Pathol. 1990 3 508-512. 

High-grade neuroendocrine carcinomas in the colon and rectum most commonly occur as a component of poorly differentiated adenocarcinomas more than 50% of the tumor should show neuroendocrine differentiation in order to be called a neuroendocrine carcinoma. Both small cell and non-small cell types exist, and both tend to stain with low-molecular-weight cytokeratin (CAM5.2) in a perinuclear dot pattern, as well as with synaptophysin, chromogranin, and/or NSE (Fig. 14.32). ° ° GDI 17 stains a substantial minority of high-grade neuroendocrine carcinomas however, immunoreactivity has not been linked to c-kit juxta-membrane (exon 11) mutations. 

High-grade (poorly differentiated) small cell and nonsmall cell neuroendocrine carcinomas can occur throughout the gastrointestinal tract but are rare. 

High-grade neuroendocrine carcinoma versus poorly differentiated nonendocrine cancer By im-... 

Sellner F, Sobhian B, De Santis M, et al. Well or poorly differentiated nonfunctioning neuroendocrine carcinoma of the pancreas a single institution experience with 17 cases. Eur J Surg Onco/. 2008 34 191-195. 

Kaifi JT, Zinnkann U, Yekebas EF, et al. LI is a potential marker for poorly-differentiated pancreatic neuroendocrine carcinoma. World J Gastroenterol. 2006 12 94-98. 

Somatostatin receptor type 2 somatostatin receptor type 2 (SST2) is a member of the somatostatin family, commonly detected in neuroendocrine tumors including small cell carcinoma of the lung. Some poorly differentiated non-neuroendocrine lung cancers show also weak expression of SST2. 

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