Malignant risk of indeterminate pediatric thyroid nodules-An institutional experience

Pediatric thyroid nodules: A comprehensive study of cytology, histology, molecular findings, and risk of malignancy with emphasis on atypia of undetermined significance category

OBJECTIVE

Pediatric thyroid nodules are more challenging in clinical practice than in adults. Herein, we report our comprehensive experience with pediatric thyroid nodules, including cytology, histology, and molecular correlation.

METHODS

Pediatric thyroid fine needle aspiration (FNA) performed from 2014 to 2024 was identified. Patients' demographics, FNA site, number and size of nodules, Bethesda category diagnosis, molecular studies, and surgical diagnoses were recorded.

RESULTS

In 310 reports, 378 nodules from 302 patients were included. Patients' mean age was 17.0 years (range, 1-21 years). Applying the Bethesda system, benign diagnoses were most common (198/378, 52.4%), while the indeterminate category of atypia of undetermined significance (AUS) was the most prevalent (51/378, 13.5%). Surgical resection was performed in 36.8% (139/378) of cases, revealing malignancy in 50.0% of AUS, 45.4% of follicular neoplasms, and 93.8% of suspicious-for-malignancy cases. Among AUS subtypes, nuclear atypia was most frequently noted (16/30, 53.3%) and linked to papillary thyroid carcinoma in half of these cases (8/16, 50.0%). The risk of malignancy (ROM) increased with age and showed a female predominance (81.9%), with 86.1% of malignancies in the 16- to 21-year age group and no malignant histology in ages 0 to 5 years. Molecular testing, including Afirma (34/38, 89.5%) and Thyroseq (4/38, 10.5%), often returned suspicious (16/34, 47.1%) or intermediate (3/4, 75.0%) results.

CONCLUSIONS

Indeterminate diagnoses in pediatrics posed a significant ROM, particularly in female adolescents and early adulthood (ages 16-21 years). The AUS category was the most common among indeterminate categories, with AUS nuclear highly associated with malignancy. No malignancy was seen in ages 0 to 5 years.

Malignant risk of pediatric Bethesda category III thyroid nodules subcategorized by nuclear atypia and other: A single institution experience

BACKGROUND

The 2023 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) divides AUS diagnoses into two major subcategories: atypia of undetermined significance (AUS) nuclear atypia (AUS-N) and other (AUS-O). This study aims to compare the histological outcome and malignant rate of pediatric AUS thyroid nodules classified into AUS-N and AUS-O subcategories.

DESIGN

A search of our institutional electronic pathology database for the period from January 2012 to July 2023 was conducted to identify pediatric (<21 years old) thyroid nodules that were interpreted as AUS and subsequently had surgery. Cases were further divided into AUS-N and AUS-O subcategories. Results of follow-up surgical resections were collected. The malignant rate was calculated and compared between AUS-N and AUS-O groups.

RESULTS

The study identified 62 thyroid nodules from 58 pediatric patients. Among these nodules, 29 and 33 were subcategorized as AUS-N and AUS-O, respectively. Both groups exhibited a female predominance and displayed a similar nodule size distribution. Histological analysis revealed 15 carcinomas in AUS-N nodules, including 11 cases of classic papillary thyroid carcinoma (PTC) and four cases of follicular type of PTC. In contrast, in the AUS-O group, a total of five carcinomas were documented, including two PTCs and three oncocytic thyroid carcinomas. Notably, the malignant rate of AUS-N nodules (52%) is significantly higher than that of AUS-O nodules (15%) (p = .002).

CONCLUSION

In pediatric AUS thyroid nodules, the malignant risk in AUS-N is significantly higher than that in AUS-O. These findings may guide more appropriate clinical triage and/or improve management of pediatric patients with AUS thyroid nodules.

Evolving approaches in paediatric thyroid cytopathology: A review

The guidelines for the workup of thyroid nodules have been established in adult populations and secondarily applied to paediatric populations. In particular, The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is commonly applied to both adult and paediatric thyroid nodules. However, as paediatric nodules have distinct molecular drivers and behavioural trajectories, there is renewed interest in diagnostic and management strategies that are paediatric specific. Here, we review key differences between paediatric and adult thyroid cancer and recent literature evaluating the use of TBSRTC in paediatric populations.

The Complex Cyto-Molecular Landscape of Thyroid Nodules in Pediatrics

Thyroid fine-needle aspiration (FNA) is a commonly used diagnostic cytological procedure in pediatric patients for the evaluation of thyroid nodules, triaging them for the detection of thyroid cancer. In recent years, greater attention has been paid to thyroid FNA in this setting, including the use of updated ultrasound score algorithms to improve accuracy and yield, especially considering the theoretically higher risk of malignancy of these lesions compared with the adult population, as well as to minimize patient discomfort. Moreover, molecular genetic testing for thyroid disease is an expanding field of research that could aid in distinguishing benign from cancerous nodules and assist in determining their clinical management. Finally, artificial intelligence tools can help in this task by performing a comprehensive analysis of all the obtained data. These advancements have led to greater reliance on FNA as a first-line diagnostic tool for pediatric thyroid disease. This review article provides an overview of these recent developments and their impact on the diagnosis and management of thyroid nodules in children.

Comparing ATA guidelines vs TI-RADS for evaluation of pediatric thyroid lesions

OBJECTIVE

To compare TI-RADS vs ATA guidelines for pediatric thyroid lesions based on ultrasound, in a retrospective study over 10 years. The primary outcome measure was sensitivity of both guidelines in diagnosing a thyroid malignancy on Fine Needle Aspiration (FNA) results.

METHODS

Retrospective data collection of all pediatric patients who had an FNA at the Primary Children's Hospital for thyroid lesions. Both guidelines were compared to determine which set of guidelines is most sensitive based on final outcome of pathology.

RESULTS

Seventy-seven patients were included in the study. All 77 underwent FNA as recommended by the ATA guidelines. 54.5% were benign, 22.1% were suspicious, and 23.4% were malignant lesions. Following the TI-RADS guidelines, 40.5% of these patients could have skipped the FNA. Using the ATA guidelines, all malignant lesions would have undergone FNA. However, using the TI-RADS guidelines, some patients with malignant lesions would have been ignored (5.6%) and some followed (22.2%) showing overall less sensitivity (75%).

CONCLUSIONS

The ATA ultrasound guidelines for evaluation of thyroid nodules in children are more sensitive in screening for well-differentiated thyroid malignancy. Increased sensitivity is due in part to the size constraint within the TIRADS system. All providers who evaluate thyroid nodules in children should use the ATA pediatric guidelines to avoid missing smaller malignancies in children.

Utility of Fine-Needle Aspirations to Diagnose Pediatric Thyroid Nodules

INTRODUCTION

Risk of malignancy for pediatric thyroid nodules classified according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is not well defined. Correlations between risk of malignancy and ancillary clinical data remain inconclusive. We report a single institutional experience of fine-needle aspiration (FNA) to improve upon current management paradigm of thyroid nodules.

METHODS

A retrospective chart review of 575 thyroid nodules was performed of 324 patients who underwent 340 FNAs between 2008 and 2018 at the Children's Hospital of Philadelphia. Demographics, ultrasound (US) characteristics, FNA cytology, surgical pathology, and ancillary data were reviewed.

RESULTS

The rate of malignancy according to TBSRTC was 0.0% for category I, 0.8% for category II, 15.6% for category III, 54.5% for category IV, 100.0% for category V, and 100.0% for category VI. The cumulative Thyroid Imaging Reporting and Data System (TI-RADS) score was significantly correlated with benign and malignant nodules on pathology (p < 2.2e-16). Distribution of TI-RADS for cytologically indeterminate nodules with benign or malignant pathology revealed significant differences for composition (p = 3.20e-8) and echogenic foci (p = 0.005) but not for echogenicity (p = 0.445), shape (p = 0.160), margins (p = 0.220), and size (p = 0.105). Distributions of thyroid-stimulating hormone levels between benign and malignant patients was significant (p = 1.58e-3).

CONCLUSIONS

Nodules with TI-RADS scores >3 should undergo FNA, irrespective of size; surgical resection is recommended for nodules classified as TBSRTC category IV and V due to high risk of malignancy. US surveillance instead of FNA can be performed for nodules with TI-RADS scores ≤3.

Predictive factors of malignancy in pediatric patients with thyroid nodules and performance of the Italian classification (SIAPEC 2014) in the outcome of the cytological FNA categories

PURPOSE

The rate of malignancy (ROM) among pediatric studies using the Bethesda System is 39.5% and 41.5% for atypia of undetermined significance/follicular lesion of undetermined significance and for suspected follicular neoplasm, respectively. Data reported on the basis of Bethesda System showed lower ROM in adults with indeterminate nodules (30.5 and 28.9% respectively). Studies on adults based on the Italian Society of Anatomic Pathology and Cytology (SIAPEC) classification, report ROM of 14.2% for TIR3a and 44.6% for TIR3b category, showing greater sensitivity in detecting malignancy. To date, no performance data are available about SIAPEC classification in pediatric age.

METHODS

Retrospective data were collected from 200 pediatric subjects with thyroid nodules in the period 2000-2020.

RESULTS

The distribution of cytological categories after fine needle aspiration biopsy (FNAB) was 7 TIR1, 4 TIR1c, 22 TIR2, 14 TIR3a, 9 TIR3b, 3 TIR4, and 16 TIR5. The surgical approach was performed in 40/200 subjects, with total ROM of 65% (0% for TIR1-TIR3a, 77.8% for TIR3b, and 100% for TIR4-TIR5). Total FNAB accuracy was 95%, while the sensibility and specificity were 92.3 and 92.6%, respectively.

CONCLUSIONS

The reported data seem to confirm a greater sensitivity of SIAPEC classification to identify malignancy within the indeterminate category also in pediatric age and not only in adulthood. This finding may orient clinicians toward clinical follow-up for the indeterminate TIR3a group and toward surgical approach with total thyroidectomy in the indeterminate TIR3b group, although this indication should be confirmed in further national multicenter studies including larger cohorts.

Thyroid nodules in children and adolescents

PURPOSE OF REVIEW

Compared with adults, there is a two-fold to three-fold increased risk of malignancy for a pediatric patient undergoing evaluation of a thyroid nodule. In 2015, the American Thyroid Association published guidelines on the evaluation and management of pediatric patients with thyroid nodules and differentiated thyroid cancer. The goal of this clinical update is to review recent additions to the literature and propose opportunities how to best incorporate these findings into clinical practice.

RECENT FINDINGS

Recent additions to the literature include assessment of ultrasound-based scoring systems to improve selection of patients for fine needle aspiration, defining the pediatric-specific risk of malignancy within The Bethesda System for Reporting Thyroid Cytopathology, and broadening our knowledge of the oncogene landscape that supports incorporation of adjunct oncogene testing to rule-in malignancy of nodules with indeterminate cytology.

SUMMARY

There have been significant additions to the literature on the evaluation and management of children and adolescents with thyroid nodules since publication of the 2015 American Thyroid Association guidelines. Incorporating these changes into clinical care, within the setting of multidisciplinary, pediatric-specific, regional centers, will maximize ongoing efforts to improve the care of children and adolescents with thyroid nodules.