COMMENTARY

Thyroid Nodules in Children Raise Risk for Cancer

Kenneth D. Burman, MD

Disclosures

October 16, 2013

A Standardized Assessment of Thyroid Nodules in Children Confirms Higher Cancer Prevalence Than in Adults

Gupta A, Ly S, Castroneves LA, et al
J Clin Endocrinol Metab. 2013;98:3238-3245

Article Summary

This study by Gupta and colleagues[1] systematically analyzed the clinical characteristics and risk for thyroid nodules to harbor thyroid cancer in the pediatric population. Pediatric patients were approached in a defined manner that included clinical examination, measurement of serum thyroid-stimulating hormone (TSH), and thyroid ultrasound. If a thyroid nodule that is 1 cm or larger was identified, ultrasound-guided fine needle aspiration (FNA) was performed. Patients with a low serum TSH had a 123-I thyroid scan. If an autonomous nodule was found, thyroid FNA was not performed.

Findings were compared with a control population of adults. Of 300 children who were originally referred for thyroid nodule evaluation, 125 had thyroid FNA after a nodule larger than 1 cm was found. In this group, the incidence of thyroid cancer was 22%, a value that is significantly higher than the rate of thyroid cancer in nodules in adults (5%-14%). The authors concluded by noting the high likelihood that a child referred for evaluation of possible thyroid nodules will not require a thyroid FNA and will have a benign condition. On the other hand, however, there is a 22% chance that a thyroid nodule identified by ultrasound that is 1 cm or larger will harbor thyroid cancer.

Viewpoint

The majority of articles about thyroid nodules and thyroid cancer assess them in adult patients.[2] Clinically detectable thyroid nodules occur in approximately 1% of men and 5% of women.[3,4] However, more sensitive methods of detection, such as ultrasound, have detected thyroid nodules in a much higher percentage of the population.[5] It is estimated that about 5%-15% of thyroid nodules will harbor cancer, depending on multiple factors such as nodule size, the patient's sex, family history, and the type and amount of radiation exposure.[6,7]

Thyroid nodules and thyroid cancer have been much less extensively studied in children. The American Thyroid Association Guidelines have reviewed the literature on this topic and recommend that the diagnostic and therapeutic approach to thyroid nodules in a child should be the same as for an adult.[2] This evaluation is important because there are some obvious differences to consider in children compared with adults. It is uncertain at what age an individual should still be considered a child for these purposes. It is difficult and more disconcerting to a child to undergo radiologic studies and thyroid FNA. Should a 2-year-old child be evaluated similarly as an 18-year-old? Moreover, the incidence of thyroid nodules is lower in children, but the percentage of these nodules that harbor thyroid cancer is not as clear as in adults.[2]

This study by Gupta retrospectively analyzed 300 consecutive children with possible thyroid nodules who were referred to a multidisciplinary pediatric thyroid cancer clinic. For various valid reasons (eg, history of radiation, familial thyroid cancer, referral bias), some patients were excluded. They analyzed 125 patients (136 FNAs) with thyroid nodules on ultrasound that were 1 cm or larger in size. FNA was performed on all nodules and was well tolerated. Patients did not require sedation except for 2 patients who were younger than 6 years of age. The female-to-male ratio of the nodules was 5:2. Patients were referred for thyroid surgery if they had cytologic abnormalities that indicated concern for cancer or if the nodule was 4 cm or larger. Thyroid cancer was identified in 28 patients for an incidence of 22%. The presence of coexistent Hashimoto thyroiditis did not influence the rate of detection of thyroid cancer, whereas nodular microscopic calcifications and the presence of abnormal cervical lymph nodes increased the risk for thyroid cancer with statistical significance. Benign thyroid cytology was found in 86 patients, of whom 2 had an encapsulated follicular variant of thyroid cancer at surgical pathology. This rate of a false-negative FNA is approximately what is seen in adults, although the sample is relatively small for comparison. Patients with thyroid FNAs showing atypical follicular lesions of unknown significance or follicular neoplasm suspicious or diagnostic of papillary thyroid cancer had similar rates of malignancy as adult patients. The authors concluded that thyroid nodules in children have a statistically significant higher rate of harboring thyroid cancer than in a comparable group of adult patients. Pediatric patients also presented with larger thyroid nodules than did adult patients.

Although retrospective, this is an excellent study. The authors used a uniform systematic approach to patients with suspected thyroid nodules. It was a single institution study in which all thyroid FNAs were evaluated by the same cytology department. They did not include autonomous thyroid nodules in patient who had a low serum TSH, and they also tried to decrease various factors that may have biased the results. Patients who were 18 years of age or younger were included, and the majority of patients were older than 10-12 years. All patients with thyroid cancer had the diagnosis confirmed with surgical pathology.

In summary, the authors found that 22% of pediatric patients with thyroid nodules that were 1 cm or larger had thyroid cancer (almost always papillary thyroid cancer), and 78% of patients had benign FNAs. The latter patients need to be followed for changes in the nodules over time. Only 2 of 86 patients with a benign thyroid FNA cytology were identified as having thyroid cancer on surgical pathology. Based on their results, the authors recommended that patients with an indeterminate or positive FNA for thyroid cancer, as well as pediatric patients with a nodule 4 cm or larger, be referred for surgery. Pediatric patients with a benign thyroid FNA can be monitored closely. A lobectomy is recommended for patients with indeterminate thyroid FNA cytology and unilateral nodules. The authors also noted that more than 50% of pediatric patients who are referred for evaluation of a suspected thyroid nodule do not require a thyroid FNA because the nodules are less than 1 cm, are autonomous, or no nodule is identified on thyroid ultrasound. On the other hand, they do recommend that pediatric patients with a thyroid nodule that is 1 cm or larger have an ultrasound, thyroid FNA, and be managed similarly to the adult population. They demonstrated that thyroid FNAs can be performed safely and with minimal concern for children and their parents.

Abstract

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