Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody .CD56 is a homophile binding glycoprotein with a role in cell–cell adhesion. It is also a marker of NK cells and NK lymphomas. This test differentiates plasma cells in myeloma (CD56+) from reactive plasmacytosis or MGUS (CD56-)