KRT7 and large cell neuroendocrine carcinoma: Fan et al. (25) reported that CK7 exhibited negative or weakly positive expression in 88.9% of SCLC cases, whereas 90.8% of LCNEC cases demonstrated partial or complete membrane reported that CK7 exhibited negative or weakly positive expression in 88.9% of SCLC, whereas partial or complete membrane-like positivity with strong intensity in 90.8% of LCNEC, and also had a clear staining pattern in the mixed carcinoma of SCLC and LCNEC.