Immunohistochemistry refers to immunohistochemistry. Usually, doctors recommend patients to further refine immunohistochemistry, not necessarily because the disease is serious, but to further identify and confirm the diagnosis of cancer, to clarify and differentiate the origin and type of cancer cells, and to formulate targeted treatment plans, and patients are advised to actively cooperate. Immunohistochemistry can mark the origin and differentiation degree of lymphohematopoietic tissues and tumor cells, and assist in diagnosing the nature of tumors. Also, through the detection of drug resistance genes in cancer tissues, it can provide a basis for patients to develop targeted treatment plans. It is also useful for differentiating hypofractionated carcinoma from sarcoma, determining the nature of metastases and small cell malignancies. Immunohistochemistry can also assist in detecting small metastatic lesions of cancer in bone marrow or lymphocytes and determining the proliferative activity of tumor tissue. Immunohistochemistry is also one of the indicators to assess the prognosis of patients after systemic treatment. In addition, immunofluorescence cytochemistry, immunoenzymatic cytochemistry, immunocolloid gold technique and radioimmunoautography are commonly used in immunohistochemistry to help confirm the diagnosis by testing tissue or cell specimens, as well as antibodies and chromosomes, depending on the type of disease, the doctor will take different tests. Therefore, patients can actively cooperate without much psychological burden.