|Summary and Explanation
||CD56 or Neural-Cell Adhesion Molecule (NCAM) is a homophilic binding glycoprotein expressed on the surface of neurons, glia and skeletal muscle. CD56 has been implicated in cell-cell adhesion, neurite outgrowth, synaptic plasticity, and learning and memory. Normal cells that stain positively for CD56 include NK cells, activated T-cells, brain and cerebellum, and neuroendocrine tissues. Tumors that are CD56-positive are Myeloma, Myeloid Leukemia, Neuroendocrine tumors, Wilm’s Tumor, Adult Neuroblastoma, NK/T cell Lymphomas, Pancreatic Acinar-cell Carcinoma, Pheochromocytoma, and Small-cell Lung Carcinoma. It is also expressed on some mesodermally-derived tumors (Rhabdomyosarcoma). Ewing’s Sarcoma/PNET is CD56-negative.