Large cell neuroendocrine carcinoma with discohesive growth pattern of the sigmoid colon resembling undifferentiated carcinoma

Yamada, Rin; Nakahara, Osamu; Takamori, Hiroshi; Komohara, Yoshihiro; Fujiwara, Minako

doi:10.1111/pin.13384

Cited by 1 publication

(1 citation statement)

References 5 publications

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“…The current case exhibited no reactivity for CK7, CK8, CK20 (reactive for keratin K7, K8, and K20 respectively) in addition to AE1/AE3, CAM5.2, and EMA. We previously reported a case of large cell neuroendocrine carcinoma in the sigmoid colon, characterized by a discohesive component resembling undifferentiated carcinoma and showing decreased expression of keratin (14). The present case further demonstrates that NEC can display lost or decreased expression of epithelial markers while maintaining its neuroendocrine morphology.…”

Section: Discussionsupporting

confidence: 65%

Gastric Small Cell Neuroendocrine Carcinoma With Loss of Epithelial Markers Expression

YAMADA,

UMEMOTO,

YONEMITSU

et al. 2024

CDP

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Background/Aim: Given that gastric small cell neuroendocrine carcinoma (SCNEC) is notably more aggressive than conventional adenocarcinoma, and a platinum-based regimen aligned with the treatment for pulmonary SCNEC is advocated when chemotherapy is needed, ensuring an accurate pathological diagnosis is paramount. Case Report: A 63-year-old man, examined for melena, underwent gastroscopy which revealed a total circumferential Borrmann type 3 lesion extending from the pylorus to the antrum of the stomach. He underwent a distal gastrectomy with D2 lymphadenectomy. The microscopic examination revealed SCNEC with a minor adenocarcinoma component. Immunohistochemically, the SCNEC was diffusely positive for synaptophysin, CD56, and INSM1, very focally positive for chromogranin A, and negative for leukocyte common antigen, CD3, and CD20. A significant observation in this case was the complete negativity for epithelial markers including keratin (CK7, CK8, CK20, CAM5.2, and AE1/AE3) and epithelial membrane antigen. Conclusion: Diffuse positivity for neuroendocrine markers, negativity for other lineage markers, and a transition from the adenocarcinoma component, if present, serve as significant diagnostic clues for gastric SCNEC with loss of epithelial markers expression. SCNEC should not be excluded solely based on the negative result for epithelial markers.

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Section: Discussionsupporting

confidence: 65%