None of the routine tests such as fine needle aspiration cytology can differentiate between follicular carcinoma (cancerous) and follicular adenoma (non cancerous) so term follicular neoplasm is given in these situations. Only way to find out if there is a cancer is by doing surgery known as hemithyroidectomy. Usually this surgery is safe in hands of experienced surgeon. After or during (frozen section can detect cancer during surgery) surgery if it turns out to be non cancerous then no further treatment is required, if it comes as malignancy then completion thyroidectomy surgery needs to be done