Thyroid cytopathology reporting by the bethesda system: a two-year prospective study in an academic institution

Evaluation of Thyroid Lesions by Fine Needle Aspiration Cytology According to Bethesda System

Aim To study cytology of various Thyroid lesions based on Bethesda system and to evaluate diagnostic accuracy of cytology by comparing it with histomorphological diagnosis whenever available. Materials and method In this study Fine needle aspiration cytology of 330 patients of clinically palpable thyroid were evaluated from June 2019 to December 2021 and categorised according to TBSRTC. 38 patients underwent surgical management in our hospital. Sensitivity, specificity, positive predictive value, negative predictive value reported under bethesda system were obtained by comparing the cytological and histopathological diagnosis where ever possible. Result The distribution of various categories from 330 evaluated thyroid nodules was as follows: 2.73% Non Diagnostic, 83.03% Benign, 0% Atypia of undetermined significance, 9.70% FN, 0.61% Suspicious for malignancy and 3.94% malignant. Sensitivity, specificity, positive predictive value, negative predictive value was 100, 60, 94.29 and 100% respectively. The diagnostic accuracy was calculated to be 94.73%. Conclusion There is a clearcut distinction between the two ends of the spectrum of non-neoplastic and neoplastic lesions of thyroid. Diagnostic accuracy of Bethesda system for reporting cytopathology for better clinical management is proven by the present study.

False positive cases in thyroid cytopathology - the experience of a single laboratory and a systematic review

INTRODUCTION

Fine needle aspiration (FNA) is fundamental in the pre-operative assessment of thyroid nodules. However, the shining success of thyroid FNA is occasionally eclipsed by false positive (FP) cytological diagnoses. We describe our experience regarding FP cytological diagnoses and present a literature review concerning FP rates.

MATERIALS AND METHODS

We retrospectively analyzed 2031 consecutive cytology reports. FP was defined as a case with "suspicious for malignancy" or "malignant" cytology, whose surgical follow-up failed to confirm the initial diagnosis of malignancy. We used the PubMed database for the literature review using specific search terms ("thyroid", "cytology", "false positive").

RESULTS

Out of 2031 FNA reports, 93 cases with "suspicious for malignancy" or "malignant" cytology underwent surgical excision. Histopathology did not confirm malignancy in 10 cases (0.6% FP rate). Nodules with FP cytology were significantly larger (P = 0.0024) than those with with TP (true positive) cytology. A review of 25 publications shows comparable results to ours with some slight differences. The majority of studies achieve a FP rate below 3%. Most FP cytological diagnoses turn out to be non-neoplastic lesions (nodular hyperplasia, adenomatous nodule, lymphocytic thyroiditis), which combined account for 80.5% of all histological diagnoses.

CONCLUSIONS

Thyroid nodules with FP cytology were larger than nodules with TP cytology. Most studies manage to adhere to the recommended FP rates, or values close to them, with some outliers. Nevertheless, the mean FP rate values are very close to the value recommended by The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). The FP rate value depends on how one defines true negative cases, which can be either histologically proven benign cases, via a benign clinical course, or by assuming that cytologically benign cases remain as such.

The combination of ACR-Thyroid Imaging Reporting and Data system and The Bethesda System for Reporting Thyroid Cytopathology in the evaluation of thyroid nodules-An institutional experience

BACKGROUND

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is widely utilised by cytopathologists. The American College of Radiology (ACR) has also proposed a thyroid imaging reporting and data system (TIRADS) to classify thyroid nodules and guide their selection for fine needle aspiration (FNA). The current study aimed to analyse the usefulness of TBSRTC in thyroid cytology reporting, to examine its histological correlation with TIRADS, and to compare the management of lesions in each cytological category in our institute to the TBSRTC recommendations.

MATERIALS AND METHODS

A retrospective study was performed on all thyroid FNAs from a 2-year period at a tertiary care centre. Histological correlations of TBSRTC and ACR TIRADS were examined for cases with surgical follow-up, and the risk of malignancy in each TBSRTC category, and sensitivity and specificity of FNA and TIRADS, were calculated.

RESULTS

A total of 337 thyroid FNAs were examined, with histological follow-up in 99 cases. Risk of malignancy in categories I-VI was 9.5%, 2.3%, 0.0, 8%, 87.5% and 100.0%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of FNA were 60.0%, 99.0%, 85.7%, and 97.5%, respectively, while those values for thyroid ultrasound were 90.3%, 72.2%, 92.9% and 65%, respectively.

CONCLUSION

The study substantiates the usefulness of TBSRTC in arriving at a more precise diagnosis. Hurthle cell lesions with atypia were the common cause of misdiagnosis. The combination of TIRADS and TBSRTC aids in better stratification of thyroid nodules and in decision making for management of lesions.

Indian experience of AUS/FLUS diagnosis: is it different from rest of Asia and the West?-A systematic review and meta-analysis

Background

Atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) is the most heterogeneous subcategory of the Bethesda system for thyroid cytopathology with laid down permissible limits of frequency and risk of malignancy (ROM). Due to differences in thyroid clinical practice worldwide, variations have been found in frequency, resection rates (RR) and ROM. Therefore, this systematic review and meta-analysis of AUS/FLUS across different regions was conducted and comparison of data from India was done with the rest of Asia and the West.

Methods

We searched PubMed and Google search engines from January 2009-Dec 2019 using terms "AUS Thyroid" and "FLUS Thyroid". Meta-analysis was performed using DerSimonian-Laird method and 95% confidence intervals were calculated using random effects model. Independent samples t-test was used to compare frequency, RR, and ROM of AUS/FLUS between India, rest of Asia and the West.

Results

Out of 15,000 studies on internet, 60 (18 Indian, 12 Asian and 30 Western) were included. Total aspirates were 201,657; 14,279 Indian, 62,448 Asian, 124,930 Western. Pooled estimates were: frequency 7.3% (6.3-8.3%), RR 41.9% (37.4-46.6%), ROM 33.3% (26.8-39.9%). Pooled prevalence of rate did not vary significantly across the three regions. Pooled prevalence of RR was highest in India (52.9%) and lowest in rest of Asia (26.5%); of ROM was highest in Asia (45.9%), lowest in the West (26.3%) (P<0.01). Statistical analysis demonstrated publication bias, limited to Indian and Western studies. Papillary thyroid carcinoma was the most common surgical diagnosis (87.9%; 1,082/1,231).

Conclusions

This meta-analysis showed differences in thyroid clinical practice followed in India, rest of Asia and the West. Although pooled prevalence of rate of AUS/FLUS was similar across the three, pooled RR and ROM varied. AUS/FLUS nodules were more frequently resected in Indian and Western studies than in rest of Asia. ROM was higher than recommended values in all three areas, being intermediate for India.

The diversities in thyroid cytopathology practices among Asian countries using the Bethesda system for reporting thyroid cytopathology

Background

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has been adopted and widely used among Asian countries. This study aims to investigate the application of TBSRTC in thyroid cytology practice among Asian countries.

Methods

We searched electronic databases including PubMed and Web of Science from 2010 to 2019. Meta-analysis of proportion and their 95% confidence intervals (CIs) were calculated using the random-effect model. Meta-regression and subgroup analysis were used to search for heterogeneity origins.

Results

We included 42 Asian studies with 84.953 fine-needle aspirations. Among six categories, benign was the most commonly diagnosed category. The resection rate (RR) and risk of malignancy (ROM) were highest in malignant and SM categories, and lowest among benign nodules. Thyroid cytology practice in Asia was characterized by a low RR and high ROM in patients with indeterminate thyroid nodules. There was a significant amount of heterogeneities of TBSRTC outputs (frequency, resection rate, and malignancy risk) among Asian countries. Meta-regression showed that the sources of heterogeneity might stem from the differences in study origin and the application of molecular testing. We highlighted the usefulness of preoperative molecular testing to select patients for surgery.

Conclusions

Our study provided insight regarding thyroid cytology practice among Asian countries. Active surveillance is commonly used in Asian practice resulting in a low RR and high ROM for indeterminate nodules. There are still variations in general thyroid cytology practice in Asia. Future guidelines and consensus regarding the application of TBSRTC in thyroid cytology practice among Asian countries are required.

Atypia of undetermined significance/follicular lesion of undetermined significance: Asian vs. non-Asian practice, and the Singapore experience

The Bethesda System for Reporting Thyroid Cytopathology has paved the way for comparisons of the practice of thyroid cytology in many different regions. However, there have been comparatively few studies documenting differences between Asian and non-Asian practice. Here, we aim to compare a few key parameters between the two regions, focusing on the indeterminate category of atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS). We compared its incidence, resection rates (RRs), risk of malignancy (ROM), rate of repeat fine needle aspiration (rFNA), ROMs of cytomorphologic subcategories of nuclear atypia (AUS-N) vs. architectural atypia (AUS-A), and, finally, the incidence of papillary thyroid carcinoma (PTC) vs. follicular neoplasms (FNs) in resected AUS/FLUS cases in Asian and non-Asian regions. Where possible, these metrics were compared with the Singapore experience from a tertiary referral institution. While the incidence of AUS/FLUS was similar in both regions, we found geographical differences in the RRs and ROMs, which may reflect a higher collective threshold for surgery in Asian countries. However, both cohorts showed higher ROMs in the AUS-N subcategory as compared to the AUS-A subcategory, supporting the subclassification of the AUS/FLUS based on the presence of nuclear atypia. We also observed a higher incidence of AUS-N coupled with a higher incidence of PTC in resected AUS/FLUS nodules in Asian cohorts, while AUS-A and follicular-patterned neoplasms featured more prominently in the non-Asian cohorts. These incidences may account for the starkly different molecular approaches that we noted-in Asian (chiefly Korean and Chinese) centers, BRAF mutational analysis was favored, while gene panels and gene expression classifiers were more frequently applied in non-Asian centers (chiefly in the United States of America). Overall, the data from Singapore appears more closely aligned to non-Asian trends, despite its geographical location in Southeast Asia and its predominantly Asian population. We conclude that there is significant heterogeneity in the outcomes of the AUS/FLUS categories between and within regions, which is only partially explained by regional variations, and may also reflect different regional diagnostic and management practices. This highlights the importance of understanding the local context in the interpretation of indeterminate Bethesda categories, rather than adopting a "one-size fits all" approach.

The Bethesda System for Reporting Thyroid Cytopathology: A Cytohistological Study

Introduction

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is a significant step to standardize the reporting of thyroid fine needle aspiration (FNA). It has high predictive value, reproducibility, and improved clinical significance.

Aim

The study was aimed to evaluate the diagnostic utility and reproducibility of "TBSRTC" at our institute. Methods and Material. The study included 646 thyroid FNAs which were reviewed by three pathologists and classified according to TBSRTC. Cytohistological correlation was done for 100 cases with surgical follow-up and the sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy, and risk of malignancy (ROM) were calculated. The interobserver variation among three pathologists was also assessed.

Results

The distribution of cases in various TBSRTC categories is as follows: I-nondiagnostic 13.8%, II-benign 75.9%, III-atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS) 1.2%, IV-follicular neoplasm (FN)/suspicious for follicular neoplasm (SFN) 3.7%, V-suspicious for malignancy (SM) 2.6%, and VI-malignant 2.8%. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy are 72.4%, 94.3%, 84%, 89.2%, and 87.9%, respectively. The ROM of various TBSRTC categories were II-8.5%; III-66.7%; IV-63.6%; and V and VI-100%. Cohen's Weighted Kappa score was 0.99 which indicates almost perfect agreement among the three pathologists.

Conclusions

Our study substantiates greater reproducibility among pathologists using TBSRTC to arrive at a precise diagnosis with an added advantage of predicting the risk of malignancy which enables the clinician to plan for follow-up or surgery and also the extent of surgery.

Differences in surgical resection rate and risk of malignancy in thyroid cytopathology practice between Western and Asian countries: A systematic review and meta-analysis

There is increasing evidence showing that clinicians employ different management strategies in their use of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). In this meta-analysis, we investigated the differences in diagnosis frequency, resection rate (RR), and risk of malignancy (ROM) between Western (ie, American and European) and Asian cytopathology practices. We searched PubMed and Web of Science from January 2010 to January 2019. Proportion and 95% CIs were calculated using a random-effect model. We used independent sample t tests to compare frequencies, RR, and ROM between Western and Asian practices. We analyzed a total of 38 studies with 145,066 fine-needle aspirations. Compared with Asian practice, Western series had a significantly lower ROM in most of TBSRTC categories, whereas the RR was not statistically different. Focusing on indeterminate nodules, the RR in Western series was significantly higher (51.3% vs 37.6%; P = .048), whereas the ROM was significantly lower (25.4% vs 41.9%; P = .002) compared with those in Asian series. The addition of Asian cohorts increased ROM for most of diagnostic categories compared with the original TBSRTC. In conclusion, this study demonstrates a difference in Western and Asian thyroid cytology practice, especially regarding the indeterminate categories. Lower RR and higher ROM suggest that Asian clinicians adopt a more conservative approach, whereas immediate diagnostic surgery is favored in Western practice for indeterminate nodules. The addition of Asian series into a meta-analysis of TBSRTC altered ROM for several categories, which should be considered in future revisions of TBSRTC.

Reproducibility of "The Bethesda System for Reporting Thyroid Cytopathology:" A Retrospective Analysis of 107 Patients

Objectives:

Fine-needle aspiration cytology (FNAC) has emerged as an indispensable tool to discriminate thyroid lesions into benign or malignant for appropriate management. The need for simplicity of communication and standardization of terminology for thyroid FNAC reporting led to introduction of “The Bethesda system for reporting Thyroid Cytopathology” (TBSRTC) in a conference held at the National Cancer Institute in 2007. This study aims at establishing the reproducibility of TBSRTC for diagnosing thyroid lesions.

Materials and Methods:

The present study comprised thyroid FNAC from 107 patients retrospectively over a period of 1.5 year (June 2013 to December 2014), which were reviewed by two trained cytopathologists and re-categorized according to TBSRTC. The interobserver variation and reproducibility of the reporting system was statistically assessed using Cohen's kappa.

Results:

The cytopathologists were in agreement in 98 out of 107 cases (91.5%). Maximum concordance was noted in benign category (91 of 96 cases; 92.85%), followed by 2 cases each in nondiagnostic/unsatisfactory (ND/US) and follicular neoplasm/suspicious for follicular neoplasm (FN/SFN) category (2.04% each) and 1 case each in atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), suspicious for malignancy (SUS), and malignant category (1.02% each). The highest diagnostic disagreement was noted among ND/US and benign and benign and FN/SFN categories.

Conclusion:

The utilization of TBSRTC for reporting thyroid cytology should be promoted in our country because it provides a homogeneous, standardized, and unanimous terminology for cytological diagnosis of thyroid lesions. The present study could substantiate the diagnostic reproducibility of this system.

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.

Malignancy Rates of Thyroid Cytology: Cyst Fluid Benign or Non-Diagnostic?

Background

We sought to investigate subgroup distribution using Bethesda classification and risks for malignancy. We also compared the malignancy risk of cases that were denoted as non-diagnostic due to cystic contents, with cases that were denoted as non-diagnostic due to presence of other features.

Material/Methods

The study included pathology test results of 1,440 thyroid nodule samples diagnosed using Bethesda classification. Results of 305 thyroidectomy excision specimens from these patients were also compared with cytology results to determine the frequency of malignancy. The non-diagnostic group was divided into two categories: those with cystic contents, and others. Malignancy rates were separately calculated for the two groups, and compared with the other classification groups.

Results

Distribution of malignancy rates by Bethesda classification were as follows: non-diagnostic 12.5% (6/48), benign 1.5% (3/198), atypia of undetermined significance/follicular lesion of undetermined significance (AFLUS) 9% (1/11), suspicious for follicular neoplasm (SFN) 37.5% (3/8), suspicious malignancy 70% (8/26), malignancy 100% (14/14).

Conclusions

Despite the limited number of cases, our study concluded that cystic content was closer to the benign category than the non-diagnostic category if the assessment was based on malignancy rates. In this group, similar to aspirations containing plenty of lymphocytes that indicates colloid or lymphocytic thyroiditis, it is still controversial whether criterion for adequacy of follicular epithelial cells should be sought, or if they should be regarded as benign in order to prevent unnecessarily performance of repeat aspirations.

Improving Bethesda Reporting in Thyroid Cytology: A Team Effort Goes a Long Way and Still Miles to Go…

CONTEXT

Fine-needle aspiration cytology is the first step in evaluation of thyroid nodules. Although the Bethesda classification for reporting thyroid cytology has been purported that this uniformity in reporting cytology thereby facilitating clinical decision-making, there are also studies indicating that the reporting percentage and the rates of malignancy in each category vary considerably from center to center making the clinical decision more difficult.

AIM AND MATERIALS AND METHODS

We looked at our retrospective cytology and histopathology data of thyroid nodules operated between 2012 and 2014 and then prospectively collected data during 2015-2016. In the prospective arm, for every thyroid nodule that was sampled, there was a discussion between the endocrinologist and the cytopathologist on the risk of thyroid cancer (based on the patient's history, examination findings, sonographic pattern, and the cytological appearance).

RESULTS

We noted that there was considerable improvement in reporting standards with the rates of nondiagnostic cytology dropping from 11% to 5%, an increased reporting of Bethesda Category 2 and 6 which are the definitive strata of benign and malignant nodules (38% to 41% in Category 2 and 7% to 11% in Category 6) with a high specificity (100%). There was a decline in numbers of Category 4 and 5 (13% to 9% in Category 4 and 12% to 3% in Category 5). The reporting prevalence of Category 3 increased from 19% to 27%.

CONCLUSIONS

We conclude that a team approach between the clinician who performs the ultrasound and the reporting cytopathologist improves Bethesda reporting, its predictive value, and thus potentially avoiding unnecessary thyroidectomies in benign thyroid nodules and hemithyroidectomies in thyroid cancers.

Vanishing tumors of thyroid: histological variations after fine needle aspiration

BACKGROUND

Fine needle aspiration (FNA) can lead to changes that extensively replace cytological confirmed thyroid lesions. These lesions, so called "vanishing tumors" can be diagnostically challenging to pathologists and therapeutically challenging for endocrinologists and surgeons. We performed a retrospective analysis to identify these tumors.

METHODS

Data of 656 patients referred for thyroid surgery was reviewed. Patients with suspicious lesions on neck ultrasound (US) underwent FNA. We compared FNA cytological and surgical pathological findings to identify vanishing tumors. FNA-induced changes such as cystic degeneration, hemorrhage, calcification, cholesterol crystals, fibrosis and granulation tissue were identified.

RESULTS

Seventeen patients (2.5%) were identified with vanishing tumors. FNA cytology was indeterminate in seven (41.1%) and benign in ten (58.8%) patients. Surgical pathology in all nodules showed regressive changes partially or entirely replacing the tumor. The mean size of vanishing tumors was 2.4±1.5 cm in greatest dimension. Seven nodules (41.1%) were entirely replaced while remaining ten nodules showed partial replacement of tumors. Three (17.6%) nodules had focal areas of optically clear nuclei suspicious of papillary thyroid carcinoma (PTC); one showed an additional focus of follicular neoplasm (FN) of uncertain malignant potential.

CONCLUSIONS

FNA-induced changes can lead to obliteration of nodules rendering pathological diagnosis with no evidence of confirmed lesions. Pathologists and surgeons should be aware of this challenging scenario.

To Establish Bethesda System for Diagnosis of Thyroid Nodules on the Basis of Fnac with Histopathological Correlation

INTRODUCTION

In October 2007, "The National Cancer Institute (NCI), Thyroid Fine Needle Aspiration State of the Science Conference" was held in Bethesda, Maryland hosted by the NCI with the intention of formulating internationally acceptable guidelines for reporting of thyroid cytopathology. This was because, thyroid FNAC have a reporting confusion due to multiplicity of category terminologies. To overcome this, The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was introduced for unifying the terminology and morphologic criteria along with the corresponding risk of malignancy. The Bethesda system for reporting thyroid cytopathology represents a major step towards standardization, reproducibility, improved clinical significance, and greater predictive value of thyroid fine needle aspirates (FNAs).

AIM

The aim of this study was to elucidate the diagnostic utility of the Bethesda system in reporting thyroid FNAs and to assess the effectiveness of FNAC in the evaluation of thyroid nodules by comparing the results with histopathological evaluation.

MATERIALS AND METHODS

The present study was carried out in our institute during the July 2012 to September 2014. In this study, 100 FNACs done which were classified according to the Bethesda system and out of them, 60 histopathological evaluations obtained from this group were evaluated. The sensitivity, specificity, positive and negative predictive values were evaluated.

RESULTS

Out of 100 FNACs, 06% were Non-diagnostic, 78% were Benign, 04% were Atypical follicular lesion of undetermined significance (AFLUS), 04% were suspicious for Follicular neoplasm (SFN), 01% were suspicious for Follicular neoplasm Hurthle cell type, 03% were suspicious for malignancy (SM), and 04% malignant. In 60 cases, data of follow-up histopathologic examination (HPE) were available. The sensitivity was 88.89% and specificity was 84.31%. The positive and negative predictive value were 50% and 97.7%, respectively.

CONCLUSION

The Bethesda system is very useful for a standardized system of reporting thyroid cytopathology, improving communication between cytopathologists and clinicians, and inter-laboratory agreement, leading to more consistent management approaches. An additional point which is in favor of the implementation of this system is that the classification is directly related to the risk of malignancy in each category, which in turn, prompts the recommended clinical management of that category, thus truly embodying the clinico-pathological correlation in its true spirit. The correlation of FNAC with histopathology is necessary before starting treatment.

Application of metabolomics in thyroid cancer research

Thyroid cancer is the most common endocrine malignancy with four major types distinguished on the basis of histopathological features: papillary, follicular, medullary, and anaplastic. Classification of thyroid cancer is the primary step in the assessment of prognosis and selection of the treatment. However, in some cases, cytological and histological patterns are inconclusive; hence, classification based on histopathology could be supported by molecular biomarkers, including markers identified with the use of high-throughput "omics" techniques. Beside genomics, transcriptomics, and proteomics, metabolomic approach emerges as the most downstream attitude reflecting phenotypic changes and alterations in pathophysiological states of biological systems. Metabolomics using mass spectrometry and magnetic resonance spectroscopy techniques allows qualitative and quantitative profiling of small molecules present in biological systems. This approach can be applied to reveal metabolic differences between different types of thyroid cancer and to identify new potential candidates for molecular biomarkers. In this review, we consider current results concerning application of metabolomics in the field of thyroid cancer research. Recent studies show that metabolomics can provide significant information about the discrimination between different types of thyroid lesions. In the near future, one could expect a further progress in thyroid cancer metabolomics leading to development of molecular markers and improvement of the tumor types classification and diagnosis.