Ultrasonography-guided fine-needle aspiration of thyroid incidentaloma: correlation with pathological findings

Thyroid nodules are commonly identified on autopsy examination. There are relatively few descriptions, however, of the frequency with which thyroid nodules are encountered incidentally during the course of other investigations. Prospective study to examine the prevalence of thyroid nodules in asymptomatic North American subjects, with palpation findings compared with findings on high-resolution ultrasonography. Palpable nodules were identified in 21 (21%) of 100 subjects, with nine solitary nodules (9%) and 12 multiple nodules (12%). In comparison, only 33 subjects were found to be free of any nodules by ultrasonography. Of the 67 subjects with abnormal ultrasound findings, 22 had solitary nodules (22%) and 45 had multiple nodules (45%). The prevalence of nodules was greater in women (72%) than in men (41%) (P < .02). A concordance rate of 49% was noted between ultrasound and findings by palpation. The data indicate that thyroid abnormalities are very common incidental findings, emphasizing the need for a conservative approach when such lesions are encountered incidentally.

High-frequency ultrasound examination of the thyroid was performed in 253 subjects (130 women and 123 men; age range, 19-50 years) that were randomly selected from the population in an area of Finland where goiter is not endemic. Thyroid echo abnormalities were detected in 69 subjects (27.3%). Prevalence of abnormalities increased with age, and women showed more lesions than did men in each of the 3 decades. The abnormality was solitary in 39 subjects (57%), multiple in 15 (22%), and diffuse in 15 (22%). Of the 68 individual nodules, 48 (70%) were smaller than 1 cm in diameter. Anechoic rounded nodules 1-5 mm in diameter were found in 28 subjects. Fine-needle aspiration biopsy was performed in 30 subjects. Cytologic examination revealed no unequivocal malignancies. In eight subjects (3.2%) with a diffuse echo abnormality, cytologic evaluation indicated lymphocytic thyroiditis. It is concluded that the prevalence of small thyroid echo abnormalities in a randomly selected adult population is rather high, a fact that supports use of a conservative approach to these types of findings.