Additionally, assessment of neuroendocrine differentiation through immunohistochemical analysis, such as positive immunostaining for chromogranin A (CgA), synaptophysin (Syn) or Neural Cell Adhesion Molecule (NCAM, also the cluster of differentiation CD56), is required to confirm the diagnosis of LCNEC [5–8]. This evidence concerns the gene NCAM1 and large cell neuroendocrine carcinoma.