Immunohistochemistry is used to exclude lesions by identifying intracellular antigens based on the principle of specific binding of antigens and antibodies, and studying the antigens to exclude lesions. Immunohistochemistry may also be performed on benign tissues. Immunohistochemistry is a pathology test that excludes the possibility of malignant tumors. Immunohistochemistry can be used to exclude lesions by showing that the tissue cells being examined are normal. The principle of immunohistochemistry is to utilize the specific binding between antigens and antibodies, and common immunohistochemistry techniques include immunoenzymatic cytochemistry, immunocolloidal gold, and immunofluorescence cytology. Immunohistochemistry can not only exclude lesions, but also determine the primary site of the tumor, and classify certain tumors to find out whether metastasis has occurred, which is useful for the formulation of treatment plans. Immunohistochemistry excludes lesions in order to determine the nature of the tissue taken, and the exclusion of lesions indicates that the tissue is normal and has no malignant potential.