Thyroid follicular tumors are not necessarily malignant. Thyroid adenoma is the most common benign thyroid tumor, which can cause hyperthyroidism and malignant transformation. Therefore, most or a small part of the affected side of cystadenoma should be removed at an early stage. Excised specimens must be examined by frozen section to determine benign or malignant thyroid tumors. After all, pathological diagnosis can confirm the benign and malignant thyroid tumors. Thyroid adenoma is a benign tumor originating from thyroid follicular cells.