Pathology, also known as surgical pathology, diagnostic pathology and oncologic pathology, is a basic medical discipline that studies the etiology, pathogenesis, pathological changes, disease outcome and regression of diseases. It provides the theoretical basis for the diagnosis, treatment and prevention of diseases by revealing the nature of diseases and the laws of occurrence and development, and is also a bridge discipline. In the process of clinical diagnosis and treatment, pathology is the most important method to diagnose diseases and provide the basis for treatment, therefore, it is also a clinical discipline. It not only tells what is the disease, but also explains what is the disease. A disease must have a certain pathological basis; a certain pathological change must appear corresponding clinical symptoms. Pathology is the main qualitative diagnostic method of clinical diseases, and American medical experts call pathology “the essence of medicine”, and clinicians call it “the judge of medicine”. Therefore, pathology occupies an important position in the field of medicine. The main examination methods of pathology are: biopsy, also known as biopsy, and pathological examination. The specimens obtained by surgical excision, endoscopic forceps, fine needle puncture, scraping and extraction are commonly used in clinical practice for sectioning and microscopic observation to make a diagnosis. In order to characterize the specimen during surgery, a rapid intraoperative freezing examination can also be done. The tissue origin of the tumor can also be further determined by doing immunohistochemistry.