Consistent with its neuroendocrine phenotype, most SCLC tumors highly express markers of neuroendocrine differentiation, such as insulinoma-associated protein 1 (INSM1), neural cell adhesion molecule 1 (NCAM1), chromogranin-A (CHGA), and synaptophysin (SYP), and are considered neuroendocrine-high [14]. Here, SYP is linked to small cell lung carcinoma.