The vast majority of thyroid cancers are papillary thyroid carcinomas, and a definitive pathologic diagnosis can be made by fine needle aspiration. However, a small percentage of papillary thyroid carcinomas have microscopic and focal changes in the nucleus and tissue structure, such as follicular papillary thyroid carcinoma, which is difficult to distinguish from normal follicular nodules. There are also some cases where a definitive diagnosis cannot be made because of insufficient specimen collection. In other words, if the tissue exhibits only 1-2 papillary carcinoma features or the lesion is a small focal lesion or the puncture material contains few cellular structures, then such puncture is unable to make a definitive diagnosis, and these cases are called suspicious papillary thyroid carcinoma and are classified as suspicious malignancy. Similarly, the inability to make a definitive diagnosis is also seen in cases of medullary carcinoma, lymphoma, undifferentiated carcinoma, etc. where FNA can usually make a definitive diagnosis. So if the FNA diagnosis is suspicious, what is the next step in treatment? Usually, patients need to undergo surgery, and intraoperative freezing can help clarify the diagnosis and surgical approach; if freezing also fails to yield a definite diagnosis, then the surgical approach can only be chosen based on the intraoperative situation, and the final diagnosis can only be confirmed by waiting for paraffin pathology, and then deciding whether the next step of treatment is needed based on the paraffin pathology. According to the literature, most patients diagnosed with suspicious papillary carcinoma by FNA are diagnosed with papillary carcinoma after surgery with a probability of about 60-75%, and the rest of cases are benign lesions. Of course, some patients may also choose conservative treatment with regular ultrasound review and repeat puncture, depending on the situation.