SYP and large cell neuroendocrine carcinoma: Immunohistochemically the reported LCNEC were positive staining for neuroendocrine markers, such as NSE, chromogranin A, and synaptophysin, CD56, and various CKs.[3] The presented case also showed positive immunoreactivity to CD56 and NSE but negative for the epithelial markers CK7 and CK20.