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 .CD68 is a glycoprotein found in the lysosomes and endosomes involved in the regulation of phagocytic activity of macrophages. CD68 is a widely used marker for histiocytes and histiocytic tumours but lacks specificity for these cells.