Neural cell adhesion molecule （NCAM）, also called CD56, is a homophilic binding glycoprotein expressed on the surface of neurons, glia and skeletal muscle. Although CD56 is often considered a marker of neural lineage commitment due to its discovery site, CD56 expression is also found in, among others, the hematopoietic system. Here, the expression of CD56 is mostly associated with, but not limited to, natural killer cells. CD56 has been detected on other lymphoid cells, including gamma delta （γδ） Τ cells and activated CD8+ T cells, as well as on dendritic cells. In anatomic pathology, pathologists make use of CD56 immunohistochemistry to recognize certain tumors. Normal cells that stain positively for CD56 include NK cells, activated T cells, the brain and cerebellum, and neuroendocrine tissues. Tumors that are CD56-positive are myeloma, myeloid leukemia, neuroendocrine tumors, Wilms' tumor, neuroblastoma, extranodal NK/T-cell lymphoma, nasal type, pancreatic acinar cell carcinoma, pheochromocytoma, paraganglioma, small cell lung carcinoma, and the Ewing's sarcoma family of tumors.