As a biomarker, CD-56 can be also expressed in normal neuroendocrine cells and neuroendocrine neoplasms, and thus, it is considered a potential neuroendocrine marker whereas the loss of its expression has been associated with increased metastatic risk, progression of malignant neoplasms such as myeloma, myeloid leukemia, pheochromocytoma, cholangiocarcinoma and paraganglioma [29,30]. This evidence concerns the gene NCAM1 and neuroendocrine neoplasm.