Characteristics of follicular tumors and nonneoplastic thyroid lesions in children and adolescents exposed to radiation as a result of the Chernobyl disaster.

BACKGROUND

In addition to the previously reported increase in incidence of thyroid carcinomas in Belarussian children after the Chernobyl disaster in April, 1986, benign thyroid lesions were also found to be increased in the exposed population.

METHODS

A total of 60 follicular neoplasms and benign nonneoplastic thyroid lesions arising after the Chernobyl disaster in children and adolescents of 7 to 18 years of age were studied.

RESULTS

The primary diagnoses in this series were follicular carcinoma in 1 (2%) case, follicular adenoma in 9 (15%), cystic adenomatoid nodule with papillae in 18 (30%), multinodular goiter in 18 (30%), diffuse hyperplasia in 2 (3%), diffuse hyperplasia with atypia and nodularity in 5 (8%), lymphocytic thyroiditis in 6 (10%), and thyroid cyst in 1 patient (2%). Additional histologic changes in thyroid glands from these patients were similar to those reported after radiation exposure, and included perifollicular fibrosis (72%), focal epithelial hyperplasia (73%), colloid accumulation (47%), follicular atrophy (33%), and cellular atypia (25%). Vascular abnormalities were found more often (75%) than previously reported in the thyroid gland after irradiation, and had a somewhat different appearance. They affected primarily medium-size arteries and were characterized by damage of the internal elastic lamina in addition to intimal fibrosis.

CONCLUSIONS

The first case of thyroid follicular carcinoma in the exposed Belarussian children was diagnosed after a latent period of 6.5 years, as compared with 4 years of minimal latency for post-Chernobyl papillary carcinomas. Among benign thyroid lesions, cystic adenomatoid nodules of papillary type and diffuse hyperplasia with cellular atypia and nodularity seem to be commonly associated with radiation exposure to the thyroid gland.