Cytological diagnosis of pediatric thyroid nodule in perspective of the Bethesda System for Reporting Thyroid Cytopathology

Performance of ACR TI-RADS and the Bethesda System in Predicting Risk of Malignancy in Thyroid Nodules at a Large Children's Hospital and a Comprehensive Review of the Pediatric Literature

While thyroid nodules are less common in children than in adults, they are more frequently malignant. However, pediatric data are scarce regarding the performance characteristics of imaging and cytopathology classification systems validated to predict the risk of malignancy (ROM) in adults and select those patients who require fine-needle aspiration (FNA) and possibly surgical resection. We retrospectively reviewed the electronic medical records of all patients 18 years of age or younger who underwent thyroid FNA at our institution from 1 July 2015 to 31 May 2022. Based on surgical follow-up from 74 of the 208 FNA cases, we determined the ROM for the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) ultrasound risk stratification system and The Bethesda System for Reporting Thyroid Cytopathology and added our results to those of pediatric cohorts from other institutions already published in the literature. We found the following ROMs for 1458 cases using ACR TI-RADS (TR): TR1. Benign: 2.2%, TR2. Not Suspicious: 9.3%, TR3. Mildly Suspicious: 16.6%, TR4. Moderately Suspicious: 27.0%, and TR5. Highly Suspicious 76.5%; and for 5911 cases using the Bethesda system: Bethesda I. Unsatisfactory: 16.8%, Bethesda II. Benign: 7.2%, Bethesda III: Atypia of Undetermined Significance: 29.6%, Bethesda IV. Follicular Neoplasm: 42.3%, Bethesda V. Suspicious for Malignancy: 90.8%, and Bethesda VI. Malignant: 98.8%. We conclude that ACR TI-RADS levels imply higher ROMs for the pediatric population than the corresponding suggested ROMs for adults, and, in order to avoid missing malignancies, we should consider modifying or altogether abandoning size cutoffs for recommending FNA in children and adolescents whose thyroid glands are smaller than those of adults. The Bethesda categories also imply higher ROMs for pediatric patients compared to adults.

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.

Cytological evaluation of thyroid nodules in children and young adults: a multi-institutional experience

PURPOSE

The utility of the Bethesda system for reporting thyroid cytopathology is debatable in determining the risk of malignancy in pediatric patients. Moreover, the upper age limit for defining the pediatric group has varied across different studies. The aim of this study is to compare the risk of malignancy (ROM) and risk of neoplasia (RON) across different Bethesda categories between the pediatric, young adult, and adult patients.

METHODS

This is a retrospective multi-institutional study performed in three Indian hospitals. ROM was calculated and compared across Bethesda categories in adult (>18 years) and pediatric age groups (≤18 years), with a subgroup analysis in young adults (19-21 years).

RESULTS

Thyroid nodules from a total of 5958 patients were subjected to fine needle aspiration. Of these 199 were pediatric (3.3%) and follow-up histology was available in 2276. The ROM and RON rates, including overall ROM/RON, were significantly higher in pediatric age group as compared to adults. Overall ROM of suspicious for malignancy and malignant categories was higher in children as compared to adults. The overall surgical resection rates were also higher in pediatric patients (45.2% vs. 35.7%; p < 0.01). The similar trend of increased ROM, RON and resection rates was seen among young adults as compared to adult age group.

CONCLUSION

Thyroid nodules presenting in children are more likely to be malignant than those in adults. Importantly, the young adult group behaved in a similar manner with regard to surgical resection rates, ROM and RON to pediatric.

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.

Improving Malignancy Prediction in AUS/FLUS Pediatric Thyroid Nodules with the Aid of Ultrasound

INTRODUCTION

The standard workup of thyroid nodules concerning for malignancy includes fine-needle aspiration (FNA). In 2015, the American Thyroid Association (ATA) guidelines for the management of pediatric thyroid nodules recommended that all nodules with a Bethesda III cytology undergo surgical resection.

OBJECTIVES

To correlate a Bethesda III cytology with histologic and clinical outcomes to determine the relevance of the ATA recommendations, and to evaluate whether Thyroid Imaging Reporting and Data System (TI-RADS) scoring could identify Bethesda III nodules at a lower risk of malignancy.

METHODS

A retrospective chart review of patients who had undergone thyroid nodule FNA from 2008 to 2018 was performed. Malignancy rates were determined for each Bethesda category. The reference standard was histopathology or 2-year follow-up of imaging outcomes for nonoperative cases. Ultrasound exams of Bethesda III nodules were reviewed and TI-RADS scores assigned.

RESULTS

A total of 143 FNA samples from 128 patients were identified. The mean age was 14.9 years (range 7-22). Twenty-two (15%) of the FNA samples were Bethesda III; the malignancy rate was 38%. A TI-RADS score was assigned in 20 of the 22 Bethesda III nodules. ROC analysis found an optimal cut-off for malignancy prediction of ≥7 points (risk category TR5). The negative predictive value was 85.7% (95% CI 35.9-99.6) and the positive predictive value was 83.3% (95% CI 57.2-98.2).

CONCLUSION

Although, at baseline, thyroid nodules with a Bethesda III classification carry a moderate risk of malignancy in the pediatric population, TI-RADS scoring can identify nodules with a lower risk within this group. If validated by larger studies, this can inform decision making and reduce unneeded surgery.

The Use of the Bethesda System for Reporting Thyroid Cytopathology in Pediatric Thyroid Nodules: A Meta-Analysis

Background: Little is known about the application of the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) in pediatric thyroid nodules. This meta-analysis was aimed to investigate the use of TBSRTC in the pediatric population. Methods: Relevant articles were searched in PubMed and Web of Science. Meta-analysis of proportion and its 95% confidence interval (CI) were computed utilizing the random-effect model. We used subgroup analyses and meta-regression to explore the sources of heterogeneities. Egger's regression test and funnel plot visualization were used to examine publication bias. Results: We included 17 articles comprising of 3687 pediatric thyroid nodules for meta-analyses. TBSRTC outputs including frequency and risk of malignancy (ROM) for the majority of categories were not statistically different from recently published meta-analysis of 145,066 thyroid nodules in adult patients. The resection rate (RR) in the pediatric group was significantly higher in most of the categories compared with published adult data: benign, 23.2% [CI = 18.6-27.9] vs. 13.0% [CI = 9.5-16.5]; atypia of undetermined significance/follicular lesion of undetermined significance, 62.6% [CI = 50.3-74.9] vs. 36.2% [CI = 29.9-42.5]; follicular neoplasm/suspicious for follicular neoplasm, 84.3% [CI = 75.2-93.4] vs. 60.5% [CI = 54.5-66.5]; and suspicious for malignancy, 93.8% [CI = 90.1-97.6] vs. 69.7% [CI = 64.0-75.5]. Conclusion: TBSRTC is a valuable tool to make clinical decisions for pediatric patients with thyroid nodules. Pediatric patients with benign and indeterminate thyroid nodules had a higher RR than adult counterpart, but ROM of these categories in adults and children was not statistically different suggesting a potential risk of overtreatment in pediatric patients. Determining the best treatment guidelines and additional tools for risk stratification must be a top priority to precisely identify the target patient groups for surgical intervention.

The application of current classification systems in pediatric cytopathology: Perspectives from the pediatric cytopathology symposium at the 20th International Congress of Cytology 2019

A pediatric cytopathology symposium was held at the recent 20th International Congress of Cytology, which convened in Sydney, Australia, in May 2019. This educational event brought together cytopathologists from different countries and different institutions to discuss some of the practical considerations when applying current diagnostic classification systems to cytopathology specimens from young (pediatric and adolescent) patients. Within the past decade, various classification systems have been developed to create more standardized terminology for cytopathology specimen reporting among institutions, which can lead to improved management guidelines based on evidence-based medicine. It is well known that a majority of the peer-reviewed publications in cytopathology discussing the usefulness of these classification schemes predominantly contain case cohorts of adult patients. Although pediatric cases are not excluded from following these diagnostic guidelines, there is less of an emphasis on this age group with respect to unique findings and management differences. Thus, discussing the role of these guidelines and their applications in pediatric cases at an international educational gathering can not only be beneficial in educating the cytopathology community about the value of applying these classification systems to pediatric populations, but also can raise awareness of unique entities in cytologic specimens obtained from young patients.

Bethesda System for Reporting Thyroid Cytopathology in Pediatric Thyroid Nodules: Experience of a Tertiary Care Referral Center

Context.—

The Management Guidelines for Children with Thyroid Nodules and Differentiated Thyroid Cancer from The American Thyroid Association recommends fine-needle aspiration (FNA) as an essential tool for evaluation and management of pediatric thyroid nodules, and The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) as a guideline to categorize FNA cytologic findings. A few publications have focused on TBSRTC categorization in children.

Objective.—

To evaluate our institutional experience of using TBSRTC in the pediatric population.

Design.—

We conducted a retrospective data search for thyroid FNA specimens from patients younger than 21 years who were assessed by using TBSRTC categorization between January 1, 2011, and September 30, 2017. Cytologic and histologic diagnoses, rate of surgical follow-up, rate of histology-proven malignancy, and cytologic-histologic concordance were assessed in comparison with our previously published adult experience.

Results.—

Among a total of 201 specimens, benign category accounted for 103 (51.2%), followed by 35 (17.4%) malignant, 30 (14.9%) atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), 14 (7.0%) nondiagnostic, 10 (5.0%) follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), and 9 (4.5%) suspicious for malignancy (SFM) categories. Surgeries were subsequently performed in 100 of the 201 cases (49.8%). All surgically removed nodules categorized as malignant and SFM by FNA showed malignancy, while malignancy was evident in various proportions of specimens classified as AUS/FLUS (5 of 16; 31.3%), FN/SFN (1 of 9; 11.1%), and nondiagnostic (1 of 7; 14.2%). No malignancy was identified in the benign category. Cytologic-histologic concordance achieved 100% in malignant, SFM, and FN/SFN categories, and exceeded beyond 85% and 50% for benign and AUS/FLUS categories, respectively.

Conclusions.—

TBSRTC is effective for appropriate categorization of pediatric thyroid nodules. Risk of malignancy in thyroid nodules is higher for the pediatric than adult population. Understanding the difference in TBSRTC categorization between children and adults may aid in achieving more appropriate evaluation and management of pediatric thyroid nodules.

Malignant risk of indeterminate pediatric thyroid nodules-An institutional experience

BACKGROUND

Few studies focus on pediatric thyroid nodules categorized under indeterminate diagnostic categories. The current study was conducted to assess the risk of malignancy of indeterminate pediatric thyroid nodules.

METHODS

A search of the institutional electronic pathology database from 01/2011 to 09/2018 was performed to identify pediatric (<21 years old) thyroid nodules that were interpreted as follicular lesion of undetermined significance (FLUS), suspicious for follicular neoplasm (SFN), or suspicious for malignancy (SFM) and subsequently managed with surgery, repeat fine-needle aspiration (FNA), or ≥ 6 months of clinical/imaging monitoring. Results of follow-up (F/U) surgical resections and repeat FNA/Afirma tests, and clinical and radiologic data were collected.

RESULTS

We identified 46 cases from 42 patients (11-20 years old, 33 females and 9 males), including 30 FLUS, 10 SFN, and 6 SFM. Twenty-five FLUS, ten SFN, and six SFM cases underwent surgery. The histology revealed carcinomas in 36% of FLUS, 20% of SFN, and 100% of SFM categories; follicular adenomas in 32% of FLUS and 80% of SFN categories; and benign nodules in 32% of FLUS category. All five nonsurgically treated FLUS cases were considered benign based on the findings of repeat FNA/Afirma tests (n = 3, 3-22 months F/U) or clinical/radiologic exams (n = 2, 8-12 months F/U).

CONCLUSIONS

Based on a limited study cohort, malignancy was identified in 36%, 20%, and 100% of surgically managed pediatric thyroid nodules categorized as FLUS, SFN, and SFM, respectively; suggesting a markedly higher malignant rate than the implied malignant risk for FLUS and SFM categories in adults.

Ultrasonography and the American Thyroid Association Ultrasound-Based Risk Stratification Tool: Utility in Pediatric and Adolescent Thyroid Nodules

BACKGROUND

Pediatric thyroid nodules are more likely to be malignant compared to those in adults and may have different concerning ultrasound (US) features. Recent adult guidelines stratify malignancy risk by US features. Our aim is to (1) describe and confirm US features that predict pediatric malignancy, and (2) apply the Adult American Thyroid Association (ATA) Risk Stratification Guidelines to a large pediatric cohort.

METHODS

We identified 112 children with 145 thyroid nodules from 1996 to 2015. Two blinded pediatric radiologists independently read all US images, described multiple features, and reported their overall impression: benign, indeterminate, or malignant. Each nodule was assigned an ATA risk stratification category. Radiologists' impressions and ATA risk stratification were compared to histology and cytology results.

RESULTS

Multiple US features including a solid composition, presence of microcalcifications, irregular margins, increased blood flow, and hypoechogenicity were associated with increased odds of malignancy. ATA risk stratification correlated with the radiologists' overall impression (p < 0.001). The sensitivity for detecting malignancy was comparable between both ATA stratification (91%) and the radiologists' overall impression (90%). The specificity of the radiologists' malignant overall impression (80%) was better compared to the ATA high risk stratification (54%).

CONCLUSIONS

At our institution, pediatric radiologists' overall impressions had similar sensitivity but better specificity for detecting malignancy than the ATA risk stratification tool by our convention. However, neither US-based methods perfectly discriminated benign from malignant nodules, supporting the continued need for fine needle aspiration for suspicious nodules. Further work is needed to develop an US-based scoring system specific to pediatric patients.

Thyroid Cytology in India: Contemporary Review and Meta-analysis

Fine-needle aspiration cytology (FNAC) is a screening test for triaging thyroid nodules, aiding in subsequent clinical management. However, the advantages have been overshadowed by the multiplicity of reporting systems and a wide range of nomenclature used. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was formulated in 2007, to give the world a uniform thyroid cytology reporting system, facilitating easy interpretation by the clinicians. Here, we review the status of thyroid FNAC in India in terms of various reporting systems used including a meta-analysis of the previously published data. An extensive literature search was performed using internet search engines. The reports with detailed classification system used in thyroid cytology were included. The meta-analysis of published data was compared with the implied risk of malignancy by TBSRTC. More than 50 studies were retrieved and evaluated. TBSRTC is currently the most widely used reporting system with different studies showing good efficacy and interobserver concordance. Ancillary techniques have, as of now, limited applicability and acceptability in thyroid cytology in India. Twenty-eight published articles met the criteria for inclusion in the meta-analysis. When compared with TBSRTC recommendations, the meta-analysis showed a higher risk of malignancy for categories I and III. Thyroid FNAC is practiced all over India. TBSRTC has found widespread acceptance, with most institutions using this system for routine thyroid cytology reporting. However, reasons for a high malignancy risk for categories I and III need to be looked into. Various possible contributing factors are discussed in the review.

McGill Thyroid Nodule Score in Differentiating Benign and Malignant Pediatric Thyroid Nodules: A Pilot Study

Objective The McGill Thyroid Nodule Score (MTNS) is a preoperative tool used to predict the risk for well-differentiated thyroid cancer given a specific nodule in adults. We evaluated the clinical utility of a modified pediatric MTNS with children and adolescents. Study Design Case series with chart review. Setting Tertiary care children's hospital. Subjects and Methods This is a retrospective chart review of 46 patients ≤18 years of age presenting with a solitary or dominant thyroid nodule treated with surgical resection between September 2008 and December 2015. The cumulative MTNS for each nodule was calculated and compared with the final pathology. Results Of 46 patients, 10 (21.7%) were diagnosed with well-differentiated thyroid cancer (80% papillary thyroid carcinoma, 10% follicular variant of papillary thyroid carcinoma, 10% follicular thyroid carcinoma). Malignant nodules were associated with a greater mean MTNS (benign, 5.72 ± 3.03; malignant, 16 ± 3.13; P < .05). The sensitivity, specificity, and positive predictive value of malignancy were 100%, 94.4%, and 83.3% for scores ≥10 and 80%, 100%, and 100% for scores ≥11, respectively. In nodules with indeterminate cytology (Bethesda III and IV), the pediatric MTNS showed good differentiation between benign and malignant disease, with mean scores of 7.95 and 12.5, respectively ( P = .006). Conclusion This pilot study suggests that a comprehensive scoring system may help assess the risk of malignancy in pediatric thyroid nodules and differentiate nodules with indeterminate cytology into higher- and lower-risk categories. Given these findings, larger, multi-institutional studies are warranted.

Bethesda System for Reporting Thyroid Cytopathology: A three-year study at a tertiary care referral center in Saudi Arabia

AIM

To stratify the malignancy risks in thyroid nodules in a tertiary care referral center using the Bethesda system.

METHODS

From January, 2012 to December, 2014, a retrospective analysis was performed among 1188 patients (15-90 years) who had 1433 thyroid nodules and fine-needle aspiration at Prince Sultan Military Medical City, Saudi Arabia. All thyroid cyto-pathological slides and ultra sound reports were reviewed and classified according to the Bethesda System for Reporting Thyroid Cytopathology. Age, gender, cytological features and histological types of the thyroid cancer were collected from patients’ medical chart and cytopathology reports.

RESULTS

There were 124 total cases of malignancy on resection, giving an overall surgical yield malignancy of 33.6%. Majority of the thyroid cancer nodules (n = 57, 46%) in Bethesda VI category followed by Bethesda IV (n = 25, 20.2%). Almost 40% of the cancer nodules in 31-45 age group in both sex. Papillary thyroid carcinoma (PTC) was the most common form of thyroid cancer among the study population (111, 89.6%) followed by 8.9% of follicular thyroid carcinoma (FTC), 0.8% of medullary carcinoma and 0.8% of anaplastic carcinoma. Among the Bethesda IV category 68% thyroid nodules were PTC and 32% FTC.

CONCLUSION

The malignancy values reported in our research were constant and comparable with the results of other published data with respect to the risk of malignancy. Patients with follicular neoplasm/suspicious for follicular neoplasm and suspicious of malignancy categories, total thyroidectomy is indicted because of the substantial risk of malignancy.