First, fine needle aspiration technology to carry out fine needle aspiration cytology diagnosis, must have: ① perfect and accurate puncture aspiration technology ② excellent smear and staining technology ③ experienced pathology cytologist combined with clinical information on the smear to make the correct judgment. When puncture is performed, the patient takes the supine position, the upper limb of the affected side is raised or placed behind the head, and a thin pillow can be placed on the back if necessary, so as to make the anterior convexity of the mass shallow. After local disinfection, the left hand will fix the mass to the superficial mass, especially the small mass, can be used in the left hand middle finger and forefinger holding fixed, such as the mass is large or deep in the location, can be used in the thumb and forefinger holding fixed, and make the skin of the shallow side of the mass tense, so as to make the mass shallow relative. Then hold the syringe in the right hand. Vertical piercing into the mass, when the tip of the needle to reach the center of the mass, back to the syringe plug to make negative pressure, and in maintaining negative pressure attraction, up and down, left and right, forward and backward to poke or rotate the needle several times, and then completely remove the negative pressure, pull out the needle. Remove the needle. Inhale air into the syringe and then press on the needle. The aspirated tissue is pushed out and quickly coated in dry and wet slices for fixation, staining and microscopic examination. The remaining tissue in the needle was pushed into a small test tube containing saline and centrifuged to make a cell block for backup. Pay attention to the puncture process, before the tip of the needle into the mass, can not be rotated to increase the negative pressure, in order to prevent blood or fat tissue and other mixed and affect the results of the determination. When the tip of the needle into the lump generally feel, and different nature of the lump its feel different, such as cystic masses often have a sense of emptiness, and can be pumped to the liquid; fibroadenoma has a sense of piercing into the hard rubber, it is not easy to suck out the tissues; and breast cancer has a sense of piercing into the unboiled potatoes, it is easy to suck out the tissues. In the process of removing the needle, make sure to completely remove the negative pressure to prevent the taken tissue from being sucked into the syringe and cannot be launched. In order to prevent the formation of local hematoma, after the completion of the operation, local light pressure should be applied for 3 to 6 minutes. In the small mass puncture due to improper force, the needle into the thoracic cavity damage to the alveoli can lead to pneumothorax, in order to avoid the occurrence of the mass can be pushed to the ribs to fix, and then puncture, can also be changed to slightly parallel to the chest wall of the direction of the needle. Clinical evaluation After the 70s, foreign literature reported that the accuracy of fine-needle aspiration cytology diagnosis of breast mass reached about 90%, the positive rate of breast cancer was 80-95, the false-positive rate was 1-2%, and the false-negative rate was 5-15%. Patients who undergo fine-needle aspiration cytology are mostly those who are difficult to be diagnosed by clinical examination and imaging tests, but their diagnostic accuracy is higher than that of clinical examination and other auxiliary tests, and the false-negative rate is low. In European countries, it is popular to combine fine-needle aspiration cytology with clinical palpation and X-ray film, and the misdiagnosis rate of 2,460 cases of breast cancer is only 1 case, and fine-needle aspiration cytology can also be combined with liquid-crystal thermography or ultrasound to improve the diagnosis rate. The main factors leading to false-negative fine needle aspiration cytology examination are: ① The diameter of the lump is small, and the puncture is inaccurate. However, it is not true that the larger the mass, the higher the positive rate. When the diameter of the mass is >5cm, the positive rate does not increase, which is due to the fact that the mass is too large, often combined with degeneration, necrosis, hemorrhage or infection, which affects the diagnostic accuracy; ② Related to the biological characteristics of the cancer, medullary carcinoma, especially those with lymphatic infiltration, has a high positive rate, while lobular carcinoma and intraductal carcinoma have a generally lower positive rate. Because of the small number of tumor cells in lobular carcinoma, it is not easy to draw enough cancer cells; while intraductal carcinoma is confined in the duct, so it is not easy to accurately puncture and collect material. In addition, cystic tumors are also prone to false-negative due to the fact that the tumor cells are only on the wall of the capsule; (3) Errors in reading films, such as highly differentiated carcinoma and benign proliferative lesions are often not easy to be differentiated cytologically; (4) Improperly grasping the negative pressure during the puncture and improper smear technique and microscopic examination are not careful, and other human factors can also lead to false-negative. In order to minimize false-negative, it is necessary to combine clinical palpation and other auxiliary examinations, and repeat puncture or hollow-core needle biopsy when necessary for patients with highly suspected malignancy and negative cytology. There are few reports about false positives, and actively growing breast fibromas and intraductal papillomas are easily misdiagnosed as malignant tumors. In addition, long-term application of corticosteroids, as well as chronic mastitis with epithelialization are also easily misdiagnosed. Progress In recent years, fine needle aspiration diagnostic method combined with other new technologies, and its diagnostic value has been newly improved. The cell specimen provided by needle aspiration is used for immunocytochemistry examination, which makes the tissue origin of certain tumors more clear. In breast cancer it is possible to carry out the detection of hormone receptors (ER, PR), oncogenes such as Her-2, p53, oncogene and oncogene inhibitor detection and the detection of drug-resistant gene products such as topoisomerase. There is also computerized image software that combines cell image indexes with DNA analysis and AgNOR (nucleolus organizing region) to form a comprehensive index. It provides a good objective index for discriminating the benign and malignant nature of tumor cells. In addition, the cells can also be used for live cell culture to study the sensitivity to anticancer drugs and the inductivity to tumor growth factors. At present, there are few units that can perform high-quality fine-needle aspiration cytology diagnosis and immunohistochemistry, and there are only a few units that can do it in our province, such as the Pathology Center of the Department of Pathology, Fujian Medical University, which has a high diagnostic accuracy and a large number of cases, and is at the advanced level in China.