Carcinoma de tireóide na infância e adolescência

Choice of tube extremity for emission of the lowest radiation dose in pediatric patients

AIMS

To compare the dosage of radiation the thyroid and gonad glands receive in pediatric patients undergoing chest X-rays, in distinct positions, towards the goal of developing of an X-ray tube positioning protocol.

METHODS

A randomized controlled clinical trial was carried out in the Pediatric Intensive Care Unit (PICU) at the Institute of Cardiology/University Foundation of Cardiology of Rio Grande do Sul, Brazil from June 2014 to September 2016. Patients were divided into two groups. One group was positioned with the thyroid gland facing the anode end of an X-ray tube, and in the other group the thyroid gland faced the cathode end. Radiographs were evaluated by five observers, following criteria recommended by the Commission of the European Communities (CEC).

RESULTS

Forty-eight pediatric patients, with a mean age of 2.0 ± 1.3 years, participated in this study. Based on the evaluation of 48 images, it was determined that the thyroid and gonad glands facing the cathode were exposed to 13.3 ± 3.1 μGy and 13.5 ± 4.1 μGy of radiation, respectively (p = 0.008). Additionally, the thyroid and gonad glands facing the anode were exposed to 11.7 ± 3.1 μGy and 12.7 ± 3.1 μGy of radiation, respectively (p = 0.007). The mean input dose in the center of the chest was 20.8 ± 9.6 μGy in both positions.

DISCUSSION

The proximity of the thyroid gland to the cathode end of the X-ray tube appears to be related to the dosage of ionizing radiation. Adverse effects associated with exposure to ionizing radiation could be minimized by positioning the thyroid gland to the anodic end of the X-ray tube.

CONCLUSION

Patients should be placed facing the anode end of the X-ray tube when taking thoracic X-rays, in order to reduce radiation exposure to the thyroid and gonad glands.ClinicalTrials.gov Identifier: NCT02925936.

Dynamic Risk Stratification in the Follow-Up of Children and Adolescents with Differentiated Thyroid Cancer

BACKGROUND

Risk stratification for persistent disease is an important step in pediatric differentiated thyroid cancer (DTC) management. The dynamic risk stratification (DRS) is a well validated system for adults, but not yet for children and adolescents. This study evaluated the DRS as well as other prognostic factors in pediatric DTC.

METHODS

Patients aged ≤18 years from four DTC tertiary teaching hospitals in Southern Brazil were included. Clinical characteristics were systematically retrieved, and all patients were classified according to the risk-stratification system of the 2015 American Thyroid Association pediatric DTC guidelines (ATA risk) and according to DRS (excellent, indeterminate, biochemical, or structural incomplete responses). Disease status was evaluated after initial therapy and at last follow-up visit.

RESULTS

Sixty-six patients aged 14.5 ± 3.0 years were studied of whom 54 (81.8%) were girls and 62 (93.9%) had papillary thyroid carcinomas. Tumor size was 2.3 cm (P25-75 1.6-3.5); 41 (63.1%) had cervical and 18 (27.7%) distant metastasis at diagnosis. All patients underwent total thyroidectomy, and 63 (95.5%) received radioiodine. Patients were classified according to DRS after initial therapy (n = 63) as follows: 21 (33%) excellent, 13 (21%) indeterminate, 6 (9%) biochemical, and 23 (37%) structural incomplete responses. Notably, after six years (P25-75 2.7-10.0), most patients remained in the same category. Interestingly, the cutoff analysis of stimulated postoperative thyroglobulin (sPOTg) through receiver operating characteristic curve showed that the value of 37.8 ng/mL showed 81% sensitivity and 100% specificity to predict an excellent response. Prognostic factors associated with persistent disease in the univariate analysis were TNM, ATA risk, DRS, and sPOTg.

CONCLUSION

DRS after initial therapy and sPOTg are strong predictors of disease outcome and might be helpful for defining follow-up strategies in pediatric DTC.

Role of Postoperative Stimulated Thyroglobulin as Prognostic Factor for Differentiated Thyroid Cancer in Children and Adolescents

BACKGROUND

Prognostic factors are essential for risk stratification in patients with differentiated thyroid carcinoma (DTC). The role of stimulated postoperative thyroglobulin (sPOTg) has been well established in adult DTC population, but it remains unclear in children and adolescents. This study aimed to evaluate potential prognostic factors in children and adolescents with DTC, with special emphasis on sPOTg analysis.

METHODS

Individuals aged ≤18 years at diagnosis were selected from a cohort of DTC patients attending the thyroid clinic of a tertiary university-based hospital. Baseline clinical and oncological characteristics, interventions, disease status, and outcomes were obtained from medical records. Clinical variables included in the univariate analysis were sex, age at diagnosis, tumor size, the presence of lymph node and distant metastasis, and sPOTg. Additionally, sPOTg was evaluated using the area under the receiver operating characteristic curve analysis.

RESULTS

Thirty-two children and adolescents with DTC (28 girls, 87.5%; the mean age at diagnosis = 14.7 ± 3.2 years) were included in this study. Thirty-one (96.9%) patients had papillary thyroid carcinoma. The median tumor size was 2.0 cm (P25-75 = 1.6-3.5), 22 patients (68.8%) had lymph node disease, and 5 (15.6%) had distant metastasis at diagnosis. All patients underwent total thyroidectomy, and 29 (90.6%) received radioactive iodine therapy. After a median follow-up of 5.0 years (P25-75 = 2.0-10.0), disease status was available for 27 patients: 15 (55.6%) patients were disease free, six (22.5%) had biochemical disease, and six (22.2%) had persistent structural disease (two cervical and four distant metastasis). Prognostic factors associated with persistent disease in the univariate analysis were lymph node and distant metastasis at diagnosis and sPOTg. According to the receiver operating curve analysis (n = 17 patients), the best sPOTg cutoff to predict disease-free status was 31.5 ng/mL, with a sensitivity and specificity of 100%.

CONCLUSION

The data demonstrate that sPOTg displayed high accuracy in predicting the risk of persistent disease in young patients with DTC.

Intrathyroidal thymic tissue surrounding an intrathyroidal parathyroid gland, the cause of a solitary thyroid nodule in a 6-year-old boy

Ectopic intrathyroidal thymic tissue is a rare occurrence; parathyroid glands sometimes occur in an intrathyroidal location, but this is uncommon. We report a 6-year-old boy who was noted to have a solitary thyroid nodule on ultrasound. A hemithyroidectomy was performed, and histological investigation revealed that the nodule consisted of ectopic intrathyroidal thymus tissue surrounding a well-defined parathyroidal gland. This condition is an exceedingly rare cause of a thyroid nodule, but intrathyroidal thymic tissue should probably be included in the differential diagnosis of solitary thyroid nodules.