Micronodulation: ultrasonographic sign of Hashimoto thyroiditis.

The purpose of this work is to assess the validity of an ultrasonographic sign, micronodulation, in the diagnosis of Hashimoto thyroiditis. Among 101 patients found to have ultrasonographic features of micronodulation, 57 patients had autoantibody test results available. Fifty-four patients were positive and three were negative for the autoantibodies. Therefore, the positive predictive value for micronodulation in diagnosing Hashimoto thyroitis is 94.7%. The micronodules were 0.1 to 0.65 cm in size, hypoechoic, and surrounded by an echogenic rim. This corresponds to accentuated lobulation on the pathologic specimen. Although micronodulation is highly diagnostic of Hashimoto thyroiditis, the ultrasonographic features of eight biopsy-proved masses caused by Hashimoto thyroiditis varied and were not specific for the disease.