Although thyroid nodules have always been “gentle”, thyroid cancer is hidden in the nodules, are they separate siblings or are they mother and children evolved from the nodules? Let’s discuss together. 1. What is the incidence of thyroid nodules? Will it evolve into thyroid cancer? At present, thyroid nodules are very common clinically. Among them, 7% to 15% of thyroid nodules are malignant lesions, that is, thyroid cancer. It can be seen that most thyroid nodules are benign lesions. At present, there is no unified opinion on the relationship between benign thyroid nodules and thyroid cancer, and there is no theoretical basis. 2.What are the special clinical symptoms of thyroid cancer? Thyroid nodules with the following conditions should be alerted or considered as thyroid cancer: (1) Cancer is more likely in male and pediatric patients, and 50% of thyroid nodules in childhood are cancerous. (2) Sudden increase in size within a short period of time. If a benign thyroid nodule is malignantly transformed into a hypofractionated or undifferentiated carcinoma of the thyroid gland, the mass may suddenly increase in size in a short period of time. (3) Compression symptoms, such as hoarseness or difficulty in inspiration. (4) The tumor is hard and solid with rough and uneven surface. (5) The tumor is obstructed or fixed and does not move up and down with swallowing. (6) Enlarged lymph nodes of cervical cancer. 3.What are the results of ultrasound examination of thyroid nodules that indicate possible malignancy? Ultrasound examination of the thyroid gland is the first and mandatory test for patients with thyroid nodules. The sonographic features of malignant nodules may include: solid hypoechoic nodules with unclear borders and irregular morphology; longitudinal to transverse diameter ratio >1; sand-like microcalcifications or punctate calcifications inside some nodules; and color Doppler ultrasonography showing sparse or abundant blood flow signals. 4. Is there a “gold standard” for the diagnosis of benign and malignant thyroid nodules? Fine needle aspiration biopsy (FNAB) is the most common method for preoperative qualitative diagnosis of thyroid nodules and is known as the “gold standard”. Therefore, for nodules suspected of being malignant, preoperative fine-needle aspiration biopsy can reduce unnecessary surgery and guide the next step in the treatment plan.