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. CD4 is a transmembrane glycoprotein and a member of the immunoglobulin family expressed on the surface of T-helper/T-inducer cells in addition to the majority of thymocytes and a subset of monocytes, macrophages, and dendritic cells. CD4 is a marker of lymphomas originated from these cells, which include the majority of peripheral T-cell lymphomas and cutaneous lymphomas, mainly mycosis fungoides