A nodule in the thyroid that reaches grade 4a is not a benign nodule and tends to be a malignant nodule. Grade 4 of thyroid nodules are further divided into 3 categories such as a, b and c. Grade 4a nodules are about 20-30% malignant, grade 4b nodules are about 50% malignant and grade 4c nodules are about 70%-80% malignant. If a thyroid nodule reaches grade 5, it should be directly diagnosed as a malignant thyroid nodule and requires surgery. 4a nodules that are larger than 1 cm should preferably be diagnosed pathologically by ultrasound-guided puncture biopsy of the nodule, and if the pathology is clearly malignant, surgical intervention is required. If the pathology is benign, no treatment is needed, and regular ultrasound review every year will be sufficient.