If the patient is found to have a grade 4C thyroid nodule, the risk of malignancy is 50-90%. Fine needle aspiration of the thyroid nodule is usually performed first, and the nature of the nodule is clarified before deciding whether observation or surgery is needed. If the nodule is found to be benign after fine-needle aspiration, and there are no compression symptoms, then observation will be carried out first; if the nodule is large and the patient has compression symptoms such as dyspnea and dysphagia, then surgical resection will be required. If the nodule is a malignant thyroid nodule, radical surgery is preferred. In addition to removing the lobe and isthmus on the side where the thyroid nodule is located, total thyroidectomy is performed if necessary, depending on the condition of the opposite lobe of the nodule. If distant metastasis is found, radiation therapy is also needed after surgery. For nodules of unknown benignity or malignancy and large size, especially single nodules with a high probability of malignancy, thyroid lobectomy or combined isthmus resection may be performed for treatment. It is recommended that once a patient finds that he or she has a grade 4C thyroid nodule, he or she should consult a doctor in a timely manner to improve the relevant examinations and standardize the treatment.