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 inciden ce of thyroid carcinomas in Belarussian children after the Chernobyl d isaster in April, 1986, benign thyroid lesions were also found to be i ncreased in the exposed population. Methods. A total of 60 follicular neoplasms and benign nonneoplastic thyroid lesions arising after the C hernobyl disaster in children and adolescents of 7 to 18 years of age were studied. Results. The primary diagnoses in this series were folli cular carcinoma in 1 (2%) case, follicular adenoma in 9 (15%), cystic adenomatoid nodule with papillae in 18 (30%), multinodular goiter in 1 8 (30%), diffuse hyperplasia in 2 (3%), diffuse hyperplasia with atypi a and nodularity in 5 (8%), lymphocytic thyroiditis in 6 (10%), and th yroid cyst in 1 patient (2%). Additional histologic changes in thyroid glands from these patients were similar to those reported after radia tion exposure, and included perifollicular fibrosis (72%), focal epith elial hyperplasia (73%), colloid accumulation (47%), follicular atroph y (33%), and cellular atypia (25%). Vascular abnormalities were found more often (75%) than previously reported in the thyroid gland after i rradiation, and had a somewhat different appearance. They affected pri marily medium-size arteries and were characterized by damage of the in ternal elastic lamina in addition to intimal fibrosis. Conclusions. Th e first case of thyroid follicular carcinoma in the exposed Belarussia n children was diagnosed after a latent period of 6.5 years, as compar ed with 4 years of minimal latency for post-Chernobyl papillary carcin omas. Among benign thyroid lesions, cystic adenomatoid nodules of papi llary type and diffuse hyperplasia with cellular atypia and nodularity seem to be commonly associated with radiation exposure to the thyroid gland.