A hard bump on the left side of the neck is seen in the following cases: First, swollen lymph nodes in the neck, which can be caused by inflammation and infection, or can be seen in malignant tumors or distant organ tumors with metastasis in the left side of the neck or supraclavicular lymph nodes, commonly gastrointestinal tumors. Infections can occur in the oral or maxillofacial area, secondary to local lymph node enlargement. Second, thyroid disease, specifically thyroid adenoma, nodular thyroid cyst or malignant tumor of the thyroid gland. If a thyroid lesion appears suddenly, it is considered to be a thyroid adenoma with intracapsular hemorrhage and painful symptoms, which can be clearly diagnosed by ultrasonography. The most effective treatment is surgery, which can be performed under local or general anesthesia, and a pathological examination is required after surgery.