SYP and large cell neuroendocrine carcinoma: Finally, SCLCs and large cell neuroendocrine carcinoma (LCNEC) are neuroendocrine tumors (NETs) that usually have neuroendocrine differentiation properties and are defined by the specific expression of chromogranin A (CHGA), synaptophysin (SYP), and neural cell adhesion molecule 1 (NCAM1) [7].