Soft tumors active in the lower left part of the thyroid gland may be benign tumors of the left thyroid gland, including thyroid adenoma, nodular goiter, and thyroglossal duct cyst. 1. Thyroid adenoma: It is the most common benign thyroid tumor. The pathology is divided into follicular adenoma and papillary adenoma. On examination, it is found to be a nodule in the anterior neck region, with smooth surface, no pressure pain, and moving up and down with swallowing. If accompanied by cystic changes or hemorrhage, it should be excised early in principle. 2. Nodular goiter: the cause may be due to the enzyme deficiency of thyroid hormone synthesis and iodine deficiency in diet. Most of the nodules are benign, and some of them may form cysts due to hemorrhage and necrosis. If the nodule is large enough to cause pressure symptoms, or if it has a tendency to become malignant, or if it is combined with the symptoms of hyperthyroidism, it should be treated surgically. 3. Thyroglossal cysts: these are congenital malformations associated with the development of the thyroid gland. The surface is smooth and can move up and down with swallowing or stretching. Surgical excision is recommended for treatment. If there is a lump in the thyroid gland, you need to seek medical treatment as soon as possible to avoid delaying your condition.