Immunohistochemistry (IHC): Using the principle of antibodies binding specifically to antigens in biological tissues to detect the antigens (e.g.proteins) in cells of a tissue section.Immunohistochemistry (IHC) is a process used to diagnose some types of cancer including mesothelioma. The procedure involves locating antigens in biopsy tissue through the use of a visual marker. Common markers include fluorescent dye, enzymes, colloidal gold and radioactive elements. If cellular events associated with cancerous tumors – such as an increase in cell death – are evident in the tissue, then the abnormal activity will be highlighted by the stained tissue sample. Immunohistochemistry cannot only help in the identification of a tumor, but it can also distinguish whether or not a tumor is benign or malignant.