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WHO Classification of Tumours
Neuroendocrine carcinoma, NOS
Appendix


Definition

Neuroendocrine carcinoma (NEC) is a poorly differentiated, highgrade malignant neoplasm composed of small cells or large to intermediate cells, sometimes with organoid features resembling neuroendocrine tumour (NET), diffusely expressing the general markers of neuroendocrine differentiation (diffuse expression of synaptophysin; faint or focal staining for chromogranin A), with marked nuclear atypia, multifocal necrosis and a high number of mitoses (> 20 per 10 HPF); high grade (G3) defined according to the proliferation fraction and histology. This definition refers to neoplasms previously classified as small cell carcinoma, large cell (neuro)endocrine carcinoma, or poorly differentiated (neuro)endocrine carcinoma
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Bosman FT, Carneiro F, Hruban RH, Theise ND (Eds.)
WHO Classification of Tumours of the Digestive System.
4th Edition
International Agency for Research on Cancer: Lyon 2010



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Commentary: Neuroendocrine tumours of the digestive system

NECs of the appendix
NECs are exceedingly rare in the appendix

Click to access Pubmed
O'Kane AM, O'Donnell ME, Shah R, Carey DP, Lee J (2008)
Small cell carcinoma of the appendix.
World J Surg Oncol 6: 4




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Rossi G, Bertolini F, Sartori G, Bigiani N, Cavazza A, Foroni M, Valli R, Rindi G, De Gaetani C, Luppi G (2004)
Primary mixed adenocarcinoma and small cell carcinoma of the appendix: a clinicopathologic, immunohistochemical, and molecular study of a hitherto unreported tumor.
Am J Surg Pathol 28: 1233-9



. Both the histology and the immunoprofile are consistent with those reported for NECs at other sites of the gastrointestinal tract. Of the two cases of NECs in the appendix so far reported, one was associated with an adenocarcinoma and the patient was alive 65 months after diagnosis, while the other patient only survived 2 months after surgery, which is consistent with the overall poor prognosis of pure NECs of other gastrointestinal sites
Click for details
Bosman FT, Carneiro F, Hruban RH, Theise ND (Eds.)
WHO Classification of Tumours of the Digestive System.
4th Edition
International Agency for Research on Cancer: Lyon 2010



.

Table: Types and characteristics of neuroendocrine neoplasms of the appendix.