Fine needle aspiration cytopathology (FNAC) is a biopsy method that uses a fine needle (0.6~0.9mm outside diameter) and a syringe to penetrate into the lesion area, cut down the cells or small tissues in the lesion by lifting and inserting, and then aspirate them out with the help of negative pressure inside the syringe, smear and stain them, and then read them under light microscope. FNAC has become one of the main means of tumor diagnosis, especially with the development of imaging technology in the past 10 years, the application of fine needle aspiration to superficial masses, such as breast, thyroid, lymph nodes, etc., under the guidance of ultrasound for cytological biopsy is the most rapid, easy and safe method for early diagnosis of tumors. It is the quickest, easiest and safest method for early diagnosis of tumors. A total of 35,829 fine needle aspiration masses were performed, of which 16,338 (45.6%) were superficial lymph nodes, 7,632 (21.3%) were breast masses, 6,986 (19.5%) were thyroid nodules, and 4,873 (13.6%) were other masses. In all cases, 9856 surgical or histological biopsies were performed, and the cytological diagnosis was consistent with 8092 cases, with an overall accuracy rate of 82.1%. In recent years, the application of fine needle aspiration cytology for the diagnosis of malignant tumors has been widely carried out in clinical practice, but there are still some factors that seriously limit its implementation: skepticism about the reliability of FNAC diagnosis; concern that FNAC may cause metastasis or spread of tumors; concern about the safety of FNAC; lack of corresponding cytopathology expert support; and inadequate fine needle aspiration technique. Puncture cytology has been developed for nearly 80 years in foreign countries and 60 years in China. It is simple, safe, accurate, rapid and economical, and has become a commonly accepted diagnostic method in various countries. In addition, the rapid development of ultrasound and other imaging-guided technology has further guaranteed safety and accuracy, making it possible to puncture many previously untouchable masses, and making the application of immunohistochemistry and other techniques to cytology a reality. The author’s experience in puncture cytology of superficial masses over the past 10 years is summarized as follows: I. Selection and localization of puncture target masses For multiple masses, especially multiple lymph nodes, in order to obtain positive masses, it is very important to select the puncture target (the proposed puncture mass) by ultrasonography, and in principle, the selection of ultrasonically suspicious abnormal masses, such as suspected malignant tumors, needs to be combined with the operator’s rich experience in ultrasound clinical work. Preoperatively, according to the morphological characteristics of the mass, such as size, margin, envelope, aspect ratio, etc., and if necessary, combined with color Doppler, ultrasonography, elastography and other techniques, try to select the abnormal mass to start. Second, the principles of collection should be taken directly from the lesion as far as possible, avoiding necrotic and inflammatory areas; the specimen should be fresh to avoid autolysis; the collection method should be safe and easy to make the patient feel less discomfort and not cause serious complications or promote tumor dissemination. C. Puncture methods Emphasize the accuracy and importance of ultrasound guidance; preferably puncture more than 3 stitches per mass, multiple masses if necessary, and multiple points and directions should be used for each mass puncture to improve the positive rate; for cystic masses, centrifugal filtration of cystic fluid and sampling of solid tissue at the margins; use negative pressure puncturer as much as possible; release the negative pressure and withdraw the needle quickly before withdrawing the needle; with the help of air pressure, the needle core or The specimen of the needle core or syringe is sprayed onto the slide with the help of air pressure. Among them, multi-point, multi-directional puncture of the mass does not involve randomly stirring the puncture needle inside the mass, which can cause massive rupture of capillaries inside the mass, increasing both complications and detrimental to the acquisition of positive cells. Rather, negative pressure should be applied as soon as the puncture needle enters the mass, maintaining lifting or rotational cutting in one direction to facilitate cell or tissue entry into the core, and then retreating the needle to the outside of the mass envelope before performing a second directional puncture. It is important not to draw the specimen inside the core into the syringe when smearing. A simpler method is to pull out the core, then draw back the syringe, and then spray the specimen inside the core onto the slide. For the fixation of specimens, 95% alcohol can be used. We should pay attention to the needle aspiration operation technique as a prerequisite for good FNAC. IV. Fine needle puncture in special sites or dangerous areas For lymph nodes around or behind the large blood vessels, under real-time ultrasound guidance, the large blood vessels should be avoided as much as possible. If the puncture path cannot be avoided, the puncture needle can be passed through the edge of the large blood vessels first, and then the large blood vessels can be plucked or compressed before puncturing into the target mass. In general, in principle, direct puncture of large vessels is not possible (unless a simple vascular puncture is done). V. For cytology-negative masses with high suspicion of malignancy, repeat puncture sampling should be performed. VI. Possible complications or side effects of FNAC For superficial masses, possible complications or side effects of FNAC include bleeding, hematoma, infection or other accidents, but according to the author’s experience and the relevant literature at home and abroad, the occurrence of side effects and the appearance of dangerous situations are extremely rare. It is very important for the diagnosis of cytopathology to be familiar with the clinical information such as specimen collection site, patient’s medical history, physical signs and positive laboratory results. Moreover, the communication between ultrasound interventionalists and cytopathologists will promote both parties to continuously improve their operation techniques, expand their diagnostic ideas, and jointly improve their diagnostic level. Possible limitations of puncture cytology ① diagnosis must be based on understanding the clinical situation, incomplete or incorrect clinical information may lead to misdiagnosis; ② only positive diagnosis has practical significance, negative reports may sometimes remain unresolved (but sometimes it can also be used as a reference for the possibility of non-positive lesions, after all, the accuracy rate today is up to 80% or more); ③ when it is easy to obtain larger biopsies safely and reliably Not advocated to be limited to cytologic diagnosis (but can be used as a preliminary screening); ix. All puncture patients need to sign an informed consent form before surgery Although fine needle aspiration cytology biopsy with needle aspiration has very few side effects and complications, many situations need to be evaluated and explained in preoperative conversations with patients, including: possible side effects, complications, medical specialties and possible accidents for patients; disposable materials to be used during surgery, etc. The limitations of puncture cytology, especially the possibility of false negatives, the possible need for multiple repeat punctures or further coarse needle punctures or even surgical excisional biopsies, etc.; medical alternatives, etc. Ten, fine needle aspiration can also do immunohistochemistry and genetic testing We often encounter very small masses, such as small lymph nodes located next to large blood vessels or heavy next to the organs, can not perform coarse needle aspiration, although sometimes semi-automatic coarse needle biopsy can be relatively safe, but many times this kind of deep location of small masses still can not obtain coarse needle pathology, if we must obtain tissue for immunohistochemistry or genetic testing, the development of subsequent treatment If we must obtain tissue for immunohistochemistry or genetic testing to develop subsequent therapies such as targeted therapy, what should we do at this time, have you ever thought about using fine needles? In fact, according to our extensive and rich clinical experience, nearly 90% of the problems can be solved by fine needle puncture, using 21G, 22G puncture needles or 5ml disposable syringes, puncture for cell wax block examination, feasible immunohistochemistry and genetic testing, of course, this requires a relatively abundant amount of cells, the operation of experienced doctors, and relatively professional puncture techniques (such as negative pressure puncture, appropriate rotational cutting, etc.), and completely professional. This requires a relatively abundant amount of cells, experienced physicians, and professional puncture techniques (e.g. negative pressure puncture, appropriate rotational cutting, etc.) to ensure that the immunohistochemical and genetic test results we want are obtained, and personally, I think this technology is worth promoting.