Thyroid nodules and cancer in children and adolescents affected by Hashimoto's thyroiditis

To investigate the rates of thyroid nodules and cancer in pediatric cases of Hashimoto's thyroiditis (HT) in Korea.

We retrospectively reviewed 89 pediatric and adolescent patients (age, 3-18.0 years) with HT who underwent thyroid ultrasonography (US) at our institution from February 2006 to July 2016. The diagnosis of HT was based on the presence of thyroid autoantibodies. The presence of any thyroid nodules with US and cytopathologic features was analyzed. The malignancy rate was also determined.

Thyroid nodules were in 20 of the 89 patients (22.4%). Eight of these 20 patients (40%) had colloid cysts, two (10%) had nodular hyperplasia, one (5%) had follicular adenoma, and two (10%) had lymphocytic thyroiditis. Seven of the 89 patients (7.9%) were confirmed to have a malignancy, all of which were papillary thyroid carcinoma (PTC); of those, five patients had diffuse sclerosing variant PTC, and two had conventional PTC on pathology.

The prevalence of thyroid nodules in children and adolescents with HT was 22.4%. The malignancy rate of children with HT was 7.9%. The malignancy rate among thyroid nodules was 35%, which is higher than the 26% rate generally reported for children with nodules. Therefore, using thyroid US to survey known or suspected thyroid nodules might be helpful in children and adolescents with HT and may provide further useful diagnostic information. Advances in knowledge: Thyroid US could help to assess HT patients who have known or suspected thyroid nodules.