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 CD7 is a membrane bound glycoprotein of 40 kD and is the earliest T-cell specific antigen to be expressed in lymphocytes. CD7 is positive in T-cells, most NK cells and thymocytes.