ESPE Abstracts

Thyroid nodules are rare in pediatric age with an incidence of 1.8–3%. However, the risk of thyroid cancer is much higher in the pediatric population compared with adults. Among the pediatric cancer survivors there is an increased risk of developing a secondary malignancy and the thyroid cancers account for about 10% of these secondary tumors. From 2004 to 2017, we have recruited 43 patients (22 females; 21 males) with thyroid nodules among a population who had presented an hematologic or solid tumors before 18 years old. The mean age at the first thyroid nodule detection was 17.3±5 years (range: 8.9–33.1). We considered ‘thyroid nodule’ every solid lesion larger than 4 mm at ultrasound evaluation. The fine needle aspiration biopsy (FNAB) was performed in thyroid nodules larger than 7 mm and/or with malignant sonographic findings (32 patients; 74.4%). According to Bethesda System, we identified 12 Tir2 (37.5%), 14 Tir3 (43.7%), 2 Tir4 (6.3%) and 4 Tir5 (12.5%). Five of 6 patients with Tir4 and Tir5 cytology underwent total thyroidectomy with an histological diagnosis of papillary carcinoma (in one patient surgery was not possible for localized scleroderma). Thirteen of 14 patients with Tir3 cytology underwent surgery (emithyroidectomy and/or total thyroidectomy) with an histological diagnosis of thyroid papillary carcinoma in 8 patients (61.5%). Totally, we diagnosed 14 thyroid carcinomas in our population (32.6%). We found a statistically significant difference in the percentage of malignant nodules between patient submitted to radiotherapy (local RT or Total Body Irradiation) and patients submitted to only chemotherapy (36.6% vs 22%). We demonstrated that patients with malignant nodules received a dose of radiotherapy inferior to patients with benign nodules (12.2±1.1 Gy vs 22.2±15.7 Gy; P=0.022), according to previous studies which indicated that thyroid cancer risk after a first childhood malignancy is curvilinear with radiation dose, increasing at low to moderate doses and decreasing at high doses. We did not find any statistically significant difference between the dimensions of malignant and benign nodules (12.9±5.7 mm vs 11.4±5.6) probably due to an early ultrasound finding of those lesions. Finally, dividing the population in two groups according to age at the diagnosis of the first malignancy (<8 and ≥8 years old), we showed that in the younger group the timing of thyroid nodule’s onset is superior to the older one (10.8±3.3 vs 8.4±5.3 years).