Thyroid cancer in children has no specific clinical manifestations in the early stage, and many children rarely feel discomfort. Once it is detected, there are already lymph node metastases in the neck and distant metastases in the lungs and bones. In general, children should be on high alert for thyroid cancer when there is a hard mass in the lateral part of the neck, especially in the anterior middle part of the neck (thyroid area), or when there is significant hoarseness. Overall, inflammatory is more likely when the neck lump is painful, and tumor is more likely when it is painless to touch. If there is a history of thyroid cancer in your family, you should be especially wary of thyroid cancer and go to the hospital promptly for examination. For parents, to detect thyroid cancer in children at an early stage, they should remember the three key words “swelling, growth and mute”: swelling, whether there is a lump in the child’s neck; growth, whether the lump is growing; mute, whether it is accompanied by hoarseness and swallowing discomfort. Although the percentage of malignant thyroid lumps in children is significantly higher than that of adults, not all thyroid lumps are malignant. Generally speaking, benign thyroid nodules are not associated with hoarseness and dysphagia. Most of them are multiple, slow growing or no significant growth, soft to touch, with clear borders, normal aspect ratio, good elasticity, no enlarged lymph nodes on the side of the neck, and no vocal cord paralysis. Thyroid cancer, on the other hand, may have discomfort such as hoarseness, difficulty in breathing and swallowing. How to choose 5 examination means At present, the main preoperative auxiliary diagnostic means regarding the nature of thyroid masses in clinical practice are: 1) Radionuclide examination: it is a non-invasive examination. The nodules in the thyroid gland can be shown as hot, warm, cool and cold nodule images during the nuclide scan. The nodules of malignant thyroid tumors can be shown as cold, cool or warm nodules, with cold nodules being more common. However, the specificity of this test is generally poor, with an accuracy rate of less than 30%, much lower than that of B-ultrasound and other tests, and it is particularly uncomfortable for children, considering the reason of radiation damage, so it is not routinely recommended. 2) Thyroid ultrasound: It is the preferred clinical test and is a non-invasive means to initially determine the benignity and malignancy of a mass. At present, for an experienced ultrasonographer, the correct diagnosis rate of thyroid cancer is close to 80%. 3) CT and MRI examinations are also non-invasive examinations that can clearly show the size and boundary of the tumor, its relationship with blood vessels, laryngeal trachea and esophagus as well as the metastasis of lymph nodes in the neck, and have a certain suggestive effect on the benignity and malignancy of the tumor. (4) Fine needle aspiration cytology examination: this is an invasive examination method, which generally does not cause the spread of cancer cells, and its correct diagnosis rate can reach 80%. However, it requires general anesthesia for children, so it is generally not recommended. 5) PET-CT: It can determine the benign and malignant nature of tumor with an accuracy rate of more than 95%, and it is also a non-invasive test, but it is expensive and radiological, so it is not easily performed. In conclusion, to diagnose thyroid cancer in children, ultrasound of thyroid gland is preferred, followed by CT and MRI. When the above tests cannot obtain the desired results, fine needle aspiration and PET-CT can be chosen.