The exact cause of thyroid cancer as the most common malignant tumor of the thyroid gland is not clear. Thyroid cancer as a malignant tumor is different from benign tumors of the thyroid gland, such as thyroid adenoma, in which the clinical symptoms are mostly painless lumps in the neck that move up and down with swallowing. However, the main difference between the two is that thyroid adenoma as a benign tumor usually has a clear border, soft texture and good mobility. Thyroid adenocarcinoma as a malignant tumor is usually hard, with unclear border and deviated mobility.