The importance of discrete swellings lies in the risk of neoplasia compared with other thyroid swellings. Some 15% of isolated swellings prove to be malignant and an additional 30–40% are follicular adenomas. The remain- der are non-neoplastic, largely consisting of areas of colloid degeneration, thyroiditis or cysts. Although the incidence of malignancy or follicular adenoma in clinically dominant swellings is approximately half of that of truly isolated swell- ings, it is substantial and cannot be ignored