SCLC shows a variable expression of neuroendocrine differentiation markers such as neural cell adhesion molecule (NCAM/CD56), chromogranin, synaptophysin, and insulinoma-associated protein 1 (INSM1), and usually presents lower protein levels than low-to-intermediate grade neuroendocrine tumors. This evidence concerns the gene NCAM1 and neuroendocrine neoplasm.