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Representative immunohistochemical programmed death-ligand 1 expression status in gastrointestinal neoplasms with H&E staining. We considered a case as positive even if the expression was weak or partially positive in the cancer cytomembrane (magnification, ×400). Top: H&E; bottom: immunohistochemical Ki-67. NEC, neuroendocrine carcinoma; H&E, hematoxylin and eosin.
