6.1 Introduction

Thyroidectomy in the pediatric population is approached similarly to the adult population, and is not necessarily significantly more complex or difficult when done by experienced surgeons who are familiar with pediatric thyroid disease. The indications for thyroidectomy are the same as in adults for many associated thyroid diseases, both benign and neoplastic. Some of the benign diseases are Graves’ disease, congenital hypothyroidism, and benign nodules that cause compressive symptoms. Among thyroid neoplasms are the well-differentiated ones like papillary thyroid carcinoma, and medullary and follicular thyroid carcinomas. For each of these thyroid cancers, there is a recommendation for total thyroidectomy for locoregional control. ¹ For the pediatric population, the behavior of these neoplastic processes may be slightly different from that for adults, but the surgical technique for resection is the same.

The incidence of thyroid malignancy in the pediatric population is different than the adult population. Differentiated thyroid carcinoma (DTC) is 1% of all cancers in prepubertal children, and up to 7% in adolescents. ² Thyroid cancer is the most common malignancy in childhood. ³ Compared to adults, children and adolescents with thyroid cancer may be more likely to present with disseminated disease. ^{4 , 5} Complete preoperative imaging of the thyroid and neck is important in a pediatric patient that may present with what appears as a solitary thyroid nodule with a biopsy diagnosis of carcinoma. Preoperative imaging may include ultrasound (US) but to be more inclusive, computed tomography (CT) is the standard of care in order to identify distant disease. ^{6 , 7} Prepubertal children with DTC have more extrathyroid extension, lymph node and lung metastasis than adolescents. Medullary thyroid cancer is more common in prepubertal patients, with the familial type more common. ^{4 , 8 , 9}

The risk factors for thyroid malignancy differ slightly compared to adults. Childhood exposure to ionizing radiation (especially in patients <5 years old), iodine deficiency, history of prior thyroid conditions, and genetic syndromes increase the risk for thyroid malignancy early on in life. ⁴

The 2015 American Thyroid Association (ATA) guidelines created a separate guideline on pediatric thyroid nodules and DTC. Thyroid nodules diagnosed in children are uncommon compared to adult counterparts, but when they are discovered, there is a greater risk of up to 22–26% for malignancy, and a higher risk for regional lymph node involvement, extrathyroidal extension, and pulmonary metastasis. ⁴ The risk of recurrence in pediatric DTC not treated by total thyroidectomy and radioactive iodine (RAI) is up to 30%. ²

In regard to gene rearrangements, the prevalence may be low in children, but when positive it is indicative of more aggressive disease. For example, the BRAF mutation is rare in children, but when positive, it indicates a more aggressive form of papillary thyroid carcinomas. ^{2 , 10} The RET oncogene mutation is also seen more commonly in pediatric papillary thyroid cancer. ^{2 , 10 , 11}

Overall, pediatric patients who present with a thyroid nodule should undergo imaging and a biopsy. If a fine needle aspiration (FNA) is positive for thyroid carcinoma, it is important to consider a CT scan of the neck and chest in order to thoroughly identify the extent of regional and distant disease. Once the extent of disease is determined, a complete plan including the surgical treatment can be shared with the patient’s multidisciplinary team and discussed with the patient and family.

6.2 Preoperative Evaluation

According to the 2015 ATA guidelines, the preoperative evaluation of thyroid nodules should include clinical examination and US. ^{1 , 4} US characteristics and clinical context, despite the size of nodule(s), should warrant need for FNA. The risk profile suggestive of family history of thyroid disease or cancer and/or history of ionizing radiation exposure is considered a significant component for consideration of FNA in a child with a thyroid nodule. ⁴ Given that the prevalence of thyroid cancers is higher for the pediatric patient when a nodule exists, there is an overall lower threshold for FNA. US findings such as microcalcifications and any evidence of cervical lymphadenopathy are important. It is highly recommended that all FNA be done under US guidance. Diffuse thyroid enlargement should prompt US, as well as the presence of cervical lymph nodes. Indeterminate FNA has a higher risk for malignancy in children than in adults, and warrants a diagnostic lobectomy as compared to a total thyroidectomy, instead of a repeat FNA. ⁴

The preoperative counseling for thyroid malignancies in children must take into account the goals of management. The goals of management for thyroid cancer are outlined nicely in Randolph et al’s chapter on pediatric thyroid in his textbook, Surgery of the Thyroid and Parathyroid Glands. ¹² According to the chapter, the principles of initial surgery are: (1) removal of primary lesion, (2) removal of any local invasive disease, (3) removal of involved cervical LN, (4) low morbidity, (5) permit accurate staging, (6) facilitate postoperative RAI when appropriate, (7) permit accurate long-term surveillance for recurrence, and (8) minimize risk for recurrence. ¹² These goals of surgery are irrespective of age, but what’s important is that experienced surgeons are involved in the initial surgical intervention for pediatric patients, given the fact that disease pathology often requires attention to the thyroid and quite possibly lymph nodes, with the least morbidity possible to clear all gross disease.

For pediatric patients with thyroid malignancy limited to the thyroid only, the general consensus is total thyroidectomy or near total thyroidectomy for papillary thyroid carcinoma, and lobectomy for micropapillary or follicular carcinoma <2 cm with no vascular invasion or other risk factors for aggressive behavior. ¹ Papillary thyroid carcinoma has an increased incidence of bilateral (30%) and multifocal disease (65%) in children with an increased risk for recurrence. ¹¹ A total thyroidectomy also allows optimization of RAI and thyroglobulin as a marker for surveillance. In children with follicular carcinoma, a lobectomy as mentioned above is regarded as appropriate surgical management, but if RAI is being considered, then a total thyroidectomy would be the recommendation. Some papers even show that a total thyroidectomy shows less risk of recurrence in children, ¹³ and even more importantly, increased survival. ¹⁴ Furthermore, pediatric patients who test positive for RET germline mutation should have a total thyroidectomy. ¹¹ Lobectomy is indicated when FNA is benign, there is an increase in size of a nodule over time, compressive symptoms, cosmetic reasons patient/parent choice, and concern for unifocal malignancy. ⁴ According to the ATA, in children with no evidence of lymph node disease, there is no role for prophylactic lymph node dissection unless there is extrathyroidal extension of the primary, or MTC has been diagnosed.

It is important to complete a comprehensive history and physical during the preoperative evaluation with a pediatric patient. Part of that evaluation is establishing a one-on-one relationship with the patient at hand, as well as a sense of trust. A conversation about the patient’s condition and frank discussion about the plan for surgical treatment should take place with the patient. Part of the comprehensive physical examination includes a full head and neck examination, including the thyroid and any cervical lymph nodes. An assessment of voice, swallow and breathing should also be made, and again if the child is old enough laryngeal examination should be considered. Laryngeal examination in the form of transnasal fiberoptic examination can be completed if the child is cooperative, but an alternative is transcutaneous laryngeal US. Transcutaneous laryngeal US is an accessible, and less invasive evaluation of the larynx using an in-office US probe over the skin and laryngeal skeleton that has been shown to be comparable to direct visualization. ¹⁵ A baseline voice assessment of the pediatric patient is just as important in order to establish expectations of voice use and vocal demands/ability after surgery. The involvement of a speech language pathology (SLP) early on is an important component of the preoperative evaluation. The prevalence of a multidisciplinary team dedicated to pediatric voice assessment is rare, but important. ¹⁶ Just as in adult patients, a preoperative voice assessment of a pediatric patient by both a specialist and an SLP team can elicit postoperative expectations and goals from the thyroid surgical standpoint.