SYP and neuroendocrine carcinoma: Moreover, MCC is considered a neuroendocrine carcinoma (NEC) for several reasons, including the cells’ resemblance to those of the diffuse neuroendocrine system, the immunohistochemical (IHC) expression of chromogranin-A (CgA), synaptophysin (SYN), CD56 and neuron-specific enolase (NSE), and the functional expression of somatostatin receptors (SSTR) during SSTR-imaging (SRI) [6,7].