Tumor pathological examination is divided into two categories: histopathological examination and cytopathological examination. Pathological examination is important for distinguishing tumors from tumor-like lesions, benign tumors or malignant tumors, the spread of malignant tumors, the type of tumors, and the malignancy of tumors. It also provides an important basis for doctors to select treatment methods and formulate reasonable treatment plans, evaluate treatment effects and judge prognosis. Through pathological examination, early cancer or precancerous lesions with less obvious symptoms can also be detected. Therefore, pathological examination plays an important role in the early diagnosis and prevention of tumors, and is the most widely used, accurate and reliable method among various diagnostic methods for tumors. 1.Histopathological examination of tumor 1.Biopsy is a method to obtain tissue specimens, including tumor cells and metastatic lymph nodes, by puncture or surgery for pathological examination, which is also called tumor biopsy, or biopsy for short. (1) Needle aspiration biopsy: The special puncture needle is used to aspirate some tissues from the suspicious mass and smear them to make a specimen for examination, which is mainly suitable for palpable masses on the body surface and has the best effect if the size is about 2cm. For visceral masses, puncture can be performed under ultrasound, X-ray or CT guidance. The diagnostic positivity rate of this test is 90% to 98%, and the results are usually available in 2 hours. (2) Clamp biopsy: Small pieces of tumor tissues are removed by endoscopic clamp, which is suitable for lesions in the gastrointestinal tract, stomach, colon, etc. (3) Excisional biopsy: The whole tumor or suspicious lymph nodes are completely excised for pathological examination, and the boundary of the excised mass must include some normal tissues. This method is suitable for small masses. (4) Excisional biopsy: It refers to the large tumor that cannot be completely excised, so endoscopic surgery can be used to excise part of the mass for biopsy, which is applicable to superficial and deep masses. In order to prevent autolysis or decay of biopsy tissue cells and to make the structure of the lesion clearer, the resected specimen must be immediately soaked in 10% formaldehyde or 95% ethanol and sent to the pathologist for observation and proper sampling, and a series of steps such as fixation, dehydration, transparency, wax staining, and then filming and staining. 2.Pathological section (1) Conventional paraffin section: applicable to the examination of various clamped, cut and excised specimens, with extensive and comprehensive sampling and stable production quality, and the results are generally available in 24 hours for small endoscopic specimens and 7 days for large surgical cut specimens. (2) Rapid sectioning: It is suitable for determining whether the lesion is a tumor or not and for cases without histopathological confirmation, and is mainly used for intraoperative consultation to understand the spread of tumor, especially the adjacent organs, tissues and lymph nodes, whether there is infiltration or metastasis, and to clarify the tumor cutting edge, whether there is tumor involvement and whether the scope of surgery is appropriate, etc. The results are generally available within 30 minutes. Rapid pathology section can not take too many samples, time is tight and technical requirements are high, so its confirmation rate is lower than that of conventional section, and there is a certain rate of misdiagnosis and delayed diagnosis. Taking frozen section as an example, the general confirmation rate is 90.4%~97.9%, the misdiagnosis rate is 0.5%~0.7%, and the delayed diagnosis rate or failure to confirm the diagnosis is 1.4%~6.1%. (3) Frozen section: It is mainly used for rapid intraoperative diagnosis to determine the nature of the lesion, the extent of resection and whether there is metastasis in the lymph nodes. The results are usually available in about 30 minutes. Tumor cytology examination is a method to diagnose tumor according to the morphological changes of tumor exfoliated cells. This method is simple, safe, accurate, rapid and economical, and the results can be obtained within 1~2 hours, and the accuracy rate is over 90%. (1) Scope of application: ①To guide the receptor determination of preoperative chemotherapy for breast cancer. (2) For patients who cannot take biopsy, such as hemophilia, patients with bleeding tendency, diabetes and some children and patients who are inconvenient to do biopsy. (3) Skin and all organs connected with the outside world such as respiratory tract, digestive tract, genitourinary tract, etc., such as smear of nasopharyngeal secretion to find cancer cells to diagnose nasopharyngeal cancer, sputum smear and tracheal flush to investigate cancer cells to diagnose lung cancer, smear of cervical secretion to investigate cervical cancer, esophageal straining to investigate esophageal cancer, gastric flush to investigate cancer cells to diagnose gastric cancer, smear of chest and abdominal fluid after centrifugal precipitation to investigate cancer cells, etc. (2) Collection methods: including scraping, rubbing, sawing and impression pressure, etc. (1) Flush fluid cell collection method: mainly collected from secretions or exudates, such as sputum, urine, breast secretions, broken tumor tissues. ② Fine needle aspiration cytology examination: thoracic cavity, pericardial cavity, abdominal cavity and subarachnoid cavity are punctured to extract body fluid for smear examination. The literature reports that the positive rate of this method is 59.8%~99.2%, among which, the positive rate of lymph node metastatic cancer, cervical cancer, esophageal cancer and reproachful portal cancer are above 90%.