The absence of blood flow signals is not always a benign disease, but it is not scientific to determine whether it is benign or malignant from the blood flow signals. To determine benign or malignant, in addition to ultrasonography to clarify the diagnosis, we need to do a puncture pathology examination, and various aspects of the examination to be able to clarify the diagnosis. The absence of blood flow signal does not mean that it is benign, it just means that the blood supply is not rich. For example, medullary thyroid carcinoma shows no blood flow signal under ultrasound, but it is a malignant tumor. On the other hand, thyroiditis and thyroid adenoma have blood flow signal under ultrasound, which are benign tumors. Therefore, it is best to go to a regular hospital, follow the doctor’s advice, do further examination to make a clear diagnosis, and carry out appropriate treatment according to the cause of the disease.