The risk of malignancy of thyroid 4a nodules is 2%~10%, and the treatment is different depending on the size and location of the nodule, which cannot be generalized. Fine-needle aspiration biopsy is usually preferred as the next treatment option for larger nodules, and surgical resection is performed if the biopsy result suggests malignancy; the routine management of thyroid 4a nodules of different sizes is as follows: 1. If it is a multifocal 4a nodule, or immediately adjacent to the peritoneum, trachea, or laryngeal reentrant nerve, ultrasound-guided fine-needle aspiration biopsy can be considered when it is >10mm; 2. For unifocal nodules ≤10mm, if they are not immediately adjacent to the peritoneum, trachea, or recurrent laryngeal nerve, follow-up may be an option; 3. Ultrasound-guided fine-needle aspiration biopsy is recommended for nodules >15 mm in diameter. If the result of ultrasound-guided fine-needle aspiration is malignant, the treatment option of surgical resection may be considered, and it is recommended to consult your doctor. If thyroid nodule category 4a is found on examination, it is necessary to consult a doctor in time, and further improve the examination, according to the comprehensive situation to formulate the next diagnosis and treatment plan.