Incidence and malignancy rates of indeterminate pediatric thyroid nodules.

BACKGROUND: The American Thyroid Association guidelines task force currently recommends definitive thyroidectomy or lobectomy after an indeterminate thyroid biopsy in children. This recommendation is based on evidence of a greater incidence and a higher risk of malignancy compared with adults in earlier pediatric studies. Such management may lead to overtreatment and unnecessary surgery for many children in the United States. METHODS: The objective of the current study was to re-evaluate pediatric thyroid nodules and assess the overall percentages and malignancy rates for indeterminate thyroid biopsies in children. In total, 302 pediatric thyroid fine-needle aspirations (FNAs) were analyzed retrospectively (2001-2018). Distribution percentages and malignancy rates were calculated for each category of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). RESULTS: Two indeterminate TBSRTC groups (atypia of undetermined significance/follicular lesion of undetermined significance and follicular neoplasm/suspicious for a follicular neoplasm) had much lower distribution percentages and malignancy rates compared with earlier pediatric series and American Thyroid Association guidelines. A meta-analysis further supported these findings and demonstrated distinctly different malignancy rates for the indeterminate groups (atypia of undetermined significance/follicular lesion of undetermined significance, follicular neoplasm/suspicious for a follicular neoplasm, and suspicious for malignancy), suggesting the need for TBSRTC category-specific management recommendations rather than a nondiscriminatory, up-front surgical approach. CONCLUSIONS: Adult patients with indeterminate preoperative thyroid cytopathology are followed by repeat biopsy and possibly molecular testing before undergoing definitive surgery. However, in children, the guidelines are considerably more aggressive and recommend definitive surgery after the first indeterminate thyroid biopsy. Here, the largest pediatric cohort to date with meta-analysis is presented, and the authors propose a re-evaluation of this up-front approach to pediatric thyroid care.