Treated Wilm's tumor in childhood as potential risk factor for second thyroid cancer

The potential risk of a treatment-induced second neoplasia affecting the thyroid is well known after radiation therapy for several types of cancer, but few cases have been related to incidental irradiation for Wilms' tumor. We report a case of a papillary thyroid carcinoma discovered in a young patient 15 years after treatment of a Wilms' tumor. An 18-year-old man was referred to our Endocrinological Department for a single 3 cm nodule in the right lobe of the thyroid. His past medical history included at the age of 2 years surgical resection, chemotherapy (actinomycin-D and vincristine) and cesium radiation therapy to the right side for a Wilms' tumor in stage III: a total dose of 7700 rads was delivered to an area of 17 x 10 cm in the right flank. After fine-needle demonstration of a follicular thyroid lesion, the patient underwent right lobectomy, followed by total thyroidectomy for histologic diagnosis of a follicular variant papillary cancer. Residual thyroid tissue was ablated by iodine-131 administration (3700 MBq), but scanning after therapeutic iodine showed radioactive uptake in the left regional lymph nodes, with elevated serum thyroglobulin off therapy (830 ng/ml). Magnetic resonance imaging confirmed the presence of lymph node enlargements and bilateral neck dissection was performed, followed by radioiodine treatment (3700 MBq) and thyroxine suppressive therapy. After 3-year follow-up the patient is disease-free. Although few cases of thyroid cancer have been reported in the literature after irradiation for a Wilms' tumor during childhood, this association should be considered in the long-term follow-up.