Sancak Yuksel, MD
Associate Professor
In contrast to adults, the diagnosis of a thyroid nodule in children is rare. In these cases, the workup and treatment generally follows the guidelines set forth by the American Thyroid Association (ATA) and the National Comprehensive Cancer Network (NCCN) for adults with thyroid nodules. There are no specific guidelines for the management of thyroid nodules in children. There are, however, well-supported reports in the literature which highlight the differences between thyroid nodules in children and in adults.
Children with thyroid nodules are more likely to present with a palpable neck mass.1 This is in contradistinction to adults, where a rising proportion of asymptomatic thyroid nodules are identified incidentally on neck or chest radiographs that are performed for an unrelated workup. With few exceptions, a similarly sized thyroid nodule will be more easily palpable in a child than an adult because of the developmental descent of the thyroid towards the chest and because of the relative increase in body habitus with age.
As in adults, the workup of a thyroid nodule in children contains four parts :
Thyroid nodules in children present a much higher risk of malignancy that in adults (25% versus 5%) .2 In light of this finding, all thyroid nodules in children must be considered worrisome until proven otherwise using ultrasound (US) and fine needle aspiration biopsy (FNAB). Nodules bearing low-risk cytology findings need to be closely monitored with interval US to confirm that there is no change in size.
A thorough history will focus on symptoms of hypothyroidism or hyperthyroidism, voice or swallow disturbance, history of malignancy, family history, and exposures to radiation. The physical examination will assess the thyroid bed, the lateral neck, and if indicated, a laryngeal examination. Laboratory studies include a thyroid panel. In nodules concerning for medullary thyroid carcinoma, a calcitonin level is indicated.
US and FNAB remain the most important studies to stratify the risk of malignancy in a thyroid nodule. The US should be performed by a radiologist, endocrinologist , or surgeon with experience in neck ultrasonography. The US evaluation includes an assessment of the thyroid gland size and echotexture as well as the sonographic characteristics of the nodule. In children, as in adults, microcalcifications are noted as a more worrisome finding, but the presence of microcalcifications is not pathognomonic for malignancy.3
An often overlooked component of the ultrasound examination includes characterization of any adenopathy in the central and lateral compartments of the neck. The practitioner should be cautioned that in many centers, an US survey of the lateral and central compartments is not routinely performed by ultrasound technicians when a ‘Thyroid Ultrasound’ is ordered. It is commonly noted that children with thyroid malignancies carry a higher risk of nodal metastases than adults (40-80% versus 20-50%).4 For this reason, the ultrasonographer should routinely perform a survey of the lateral and central neck as part of the workup of all pediatric thyroid nodules.
Stevens et al. reported on the favorable specificity and sensitivity of FNAB in pediatric thyroid nodules. A meta-analysis of twelve studies suggests a sensitivity and specificity of 94% and 81%, respectively.5 In children, sedation may be required to perform an adequate FNA. All abnormal lateral neck nodes should also undergo FNA at the same sitting. It is preferable to determine pathologic adequacy of the cytology specimen at the time of the FNAB in order to eliminate the need for a second sedation to repeat the FNA.
In pediatric thyroid nodules that are found to have malignant cytologic features, total thyroidectomy is recommended. A central compartment nodal dissection, while potentially increasing the risk of surgical hypoparathyroidism and recurrent laryngeal nerve injury, is indicated in cases with suspicious adenopathy in the central neck. Lateral neck dissection should only be performed in cases where there is US and/or FNAB evidence of metastases. In patients with lateral neck metastases, a formal neck dissection is preferred over “berry picking” and may decrease the risk of recurrent or residual disease in the neck. Pediatric thyroid surgery is ideally performed by a high-volume thyroid surgeon.
Post-operative radioactive iodine is indicated for pediatric thyroid nodules with high risk features, including distant metastases, positive margins, extrathyroidal extension, and aggressive histologies . The oncologic benefit of post-operative radioactive iodine therapy must be balanced against the risk, which may include secondary malignancies related to radiation exposure. Furthermore, dosing algorithms for radioactive iodine in children are not well established, and should therefore be performed in tertiary centers with experience in pediatric cancer.
Children with well-differentiated thyroid cancer tend to present with more advanced disease than in adults. Some reports suggest that as many as 10-20% of pediatric thyroid cancer patients will have evidence of distant metastases on initial workup. However, prognosis for children with well-differentiated thyroid cancer remains very favorable and approaches nearly 100% 10-year survival 1.The favorable survival of children with thyroid carcinoma reflects the finding that the most pediatric thyroid malignancies are well-differentiated and display very good uptake of radioactive iodine.