Immunohistochemistry, i.e., immunohistochemical testing, is a commonly used test in pathological diagnosis and is the gold standard for clinical diagnosis of tumors. It has a guiding role in further determining the nature of lesions, identifying metastases, judging prognosis and guiding treatment. 1. To further determine the nature of lesions to determine whether they are benign or malignant lesions, which are difficult to diagnose under ordinary pathological sections, so immunohistochemistry is needed. 2. To determine the presence of malignant tumor cells in the lymph node tissue of metastatic foci, immunohistochemistry can determine the origin of the tumor and provide a basis for the clinical treatment plan. 3. In order to determine the prognosis and guide the treatment to choose suitable anti-cancer drugs and programs, therefore, immunohistochemistry is of great significance in clinical application. Patients are advised to follow the doctor’s instructions and actively cooperate with the doctor’s treatment in order to avoid delaying the condition.