Thyroid 4c is the ultrasound classification of thyroid nodules, which can be benign or malignant, with benign being more likely. A thyroid nodule with a 4c level suggests a 30%-50% chance of malignancy, which is only slightly lower than the chance of benignity. A nodule at this level needs to be biopsied promptly, usually by fine needle aspiration of the thyroid nodule to remove a small amount of diseased tissue for pathological examination, which is the gold standard for determining benign or malignant tumors. If cancer cells are found or if there is a high tendency of malignant transformation, the lesion should be removed surgically in time and the lesion should be examined again. If the nodules are confirmed to be benign, there is no major problem.