A hard mass on the side of the neck is considered to be caused by enlarged lymph nodes in the neck, and there are obvious symptoms of tenderness on examination, including inflammatory enlargement and metastasis of the tumor. Further color ultrasound of the neck and enhanced CT examination of the neck are needed. Because of the common occurrence of thyroid diseases, especially thyroid cancer, including differentiated thyroid cancer and undifferentiated thyroid cancer, radical resection should be chosen after diagnosis, provided there is no distant metastasis. For localized lymph node enlargement due to simple inflammation, the patient may also have fever and significant pain, which should be treated with intravenous anti-infection therapy. The patient should also be monitored for changes in blood count and liver and kidney function indicators during treatment. Local warm compresses with physiotherapy can also relieve the patient’s discomfort to a certain extent. Special attention should be paid to the enlarged lymph nodes in the supraclavicular fossa