PMC5858677_01
Hematoxylin and eosin (HE) stains and immunohistochemistry (IHC) of a pure neuroendocrine carcinoma (NEC). (a) Low-power view of the NEC centered in the submucosa. (b) Medium-power view of (a) reveals relatively monomorphic cells with stippled ("salt and pepper") chromatin. Mitotic figures and necrosis are common. (c) NEC cells show strong cytoplasmic immunoreactivity for synaptophysin, while non-neoplastic glands stain negative. (d) Ki-67 IHC reveals a high Ki-67 index (70%), indicating a highly proliferative tumor.
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Both components of the carcinoma were represented with 30% (Figure 1).
PMC5858677_02
Hematoxylin and eosin (HE) stains and immunohistochemistry (IHC) of a mixed adenoneuroendocrine carcinoma (MANEC). (a) HE stains reveal a classic adenocarcinoma component with glandular growth pattern as well as a surrounding neuroendocrine component. (b and c) Using synaptophysin IHC, the neuroendocrine proportion shows strong cytoplasmic staining, while the glands of the adenocarcinoma component stain negative (asterisk). (d) Ki-67 IHC of the neuroendocrine component shows a high Ki-67 index (>90%).
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Proliferative activity 70%-80%, positive for synaptophysin, negative for cytokeratin 20, CDX2, and TTF-1 (Figure 2).