The new 4th edition World Health Organization classification for thyroid tumors, Asian perspectives

The influence of cancer on the reprogramming of lipid metabolism in healthy thyroid tissues of patients with papillary thyroid carcinoma

BACKGROUND AND OBJECTIVES

Over the years we observed changes in the metabolism of glucose, amino acids, fatty acids (FA) and nucleotides in cancer cells in order to maintain their viability and proliferate. Moreover, as the latest data show, cancer also forces a complete change in the behavior of other tissues. For instance, fat-filled adipocytes are often found in the vicinity of invasive solid human tumors. We investigated the effects of papillary thyroid carcinoma (PTC) on the lipid metabolism of healthy tissue distant from the tumor.

METHOD

Thyroid tissue was collected from female patients immediately after surgical removal of the entire thyroid gland. Blood samples were collected from PTC patients and healthy volunteers. Real-time PCR assays were performed to analyze the expression of lipogenic genes and a broad panel of FA was determined using the gas chromatography-mass spectrometry method.

RESULTS

The concentration of lipids was higher in paratumor tissue than in healthy thyroid tissue (p = 0.005). The lipogenic genes tested were significantly increased in paratumor tissue compared to healthy tissue, especially enzymes related to the synthesis of very long-chain saturated and polyunsaturated FAs (VLCSFAs and PUFAs, respectively) (p < 0.001). The FA profile also showed increased levels of C22-C26, VLCSFAs and almost all PUFAs in paratumor tissue (p < 0.05).

CONCLUSION

Our study suggests that a restructuring of lipid metabolism occurs in the adjacent healthy thyroid gland and that the metabolism of VLCSFAs and PUFAs is higher in the paratumor tissue than in the distant tissue of the healthy thyroid gland.

A Comprehensive Review and Insights into the New Entity of Differentiated High-Grade Thyroid Carcinoma

Differentiated high-grade thyroid carcinoma (DHGTC) is a new subset within the spectrum of thyroid malignancies. This review aims to provide a comprehensive overview of DHGTC, focusing on its historical perspective, diagnosis, clinical characteristics, molecular profiles, management, and prognosis. DHGTC demonstrates an intermediate prognosis that falls between well-differentiated thyroid carcinoma and anaplastic thyroid carcinoma. Previously unenumerated, this entity is now recognized for its significant impact. Patients with DHGTC often present at an older age with advanced disease and exhibit aggressive clinical behavior. Molecularly, DHGTC shares similarities with other thyroid malignancies, harboring driver mutations such as BRAFV600E and RAS, along with additional late mutations. The unique behavior and histologic features of DHGTC underscore the necessity of precise classification for prognostication and treatment selection. This highlights the critical importance of accurate diagnosis and recognition by pathologists to enrich future research on this entity further.

Decabromodiphenyl ether exposure reduces dabrafenib sensitivity of papillary thyroid carcinoma harboring BRAFV600E mutation through the EGFR-CRAF-MAPK pathway: An in vitro study

Decabromodiphenyl ether (BDE209) has been demonstrated to be associated with thyroid dysfunction and thyroid carcinoma risk as a widely used brominated flame retardants. Although dabrafenib has been confirmed to be a promising therapeutic agent for papillary thyroid carcinoma (PTC) harboring BRAFV600E mutation, the rapid acquired dabrafenib resistance has brought a great challenge to clinical improvement and the underpinning mechanisms remain poorly defined. By treating PTC-derived and normal follicular epithelial cell lines with BDE209, we assessed its impact on the MAPK pathway's activation and evaluated the resultant effects on cell viability and signaling pathways, utilizing methods such as Western blot, IF staining, and RNA-seq bioinformatic analysis. Our findings reveal that BDE209 exacerbates MAPK activation, undermining dabrafenib's inhibitory effects by triggering the EGFR pathway, thereby highlighting BDE209's potential to diminish the pharmacological efficacy of dabrafenib in treating BRAF-mutated PTC. This research underscores the importance of considering environmental factors like BDE209 exposure in the effective management of thyroid carcinoma treatment strategies.

Oncocytic Hyperplastic Nodule Versus Oncocytic Adenoma: Diagnostic Controversies Through a Brief Investigative Case Series Study

Oncocytes are frequently encountered in routine thyroidectomies. The distinction between oncocytic hyperplastic nodules and oncocytic adenomas (OAs) may be challenging. Although both entities are benign, a precise diagnosis is essential. We present two cases of solitary oncocytic lesions carrying pathogenic mutations in the p53 and NRAS genes, respectively, leading to a histological diagnosis of oncocytic hyperplastic nodules. Additionally, similar oncocytic nodules from two cases of autoimmune thyroiditis did not show any significant findings on molecular analysis (next-generation sequencing, NGS). Hence, this brief investigative series study is of particular diagnostic interest because it prompts pathologists to use the term adenoma when a solitary oncocytic nodule is encountered, regardless of the established criteria for the diagnosis of adenoma. This viewpoint leads to the possible need for the reevaluation of the histological criteria of adenomas when it comes to oncocytic lesions in order to gain a common diagnostic approach and nomenclature among pathologists and overcome any controversies in such cases.

Diagnostic and prognostic utility of TROP-2, SLP-2, and CXCL12 expression in papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most frequent thyroid malignancy. Histopathological examination is widely accepted as the gold standard test for the diagnosis of PTC. However, the histopathological examination sometimes can't differentiate PTC from other thyroid diseases. Differentiating PTC from other thyroid diseases is essential for a therapeutic approach and prognosis.

OBJECTIVES

The current study was performed to investigate the utility of TROP-2, SPL-2, and CXCL12 mRNA and protein expression in discriminating PTC from other thyroid diseases that mimic PTC.

METHODS

The current study was performed on 75 cases of surgically resected thyroid glands. The cases were distributed in two groups: the PTC group and the non-PTC group. The PTC group consisted of 35 cases (25 patients of the classic PTC variant and 10 patients of the PTC follicular variant). The non-PTC group consisted of 40 cases (10 cases were multinodular goiter, 5 cases were Graves' disease, 5 cases were Hashimoto thyroiditis, 15 patients were follicular adenoma (FA) and 5 cases were follicular carcinoma). TROP-2, SPL-2, and CXCL12 mRNA expression were estimated by qRT-PCR, and protein expression was estimated by immunohistochemistry.

RESULTS

There were upregulated TROP-2, SPL-2, and CXCL12 mRNA and protein expressions in PTC compared to non-PTC (P< 0.001, for each). There was a statistically significant upregulation in the mRNA expression of the three genes among PTC cases with larger tumor sizes (P< 0.001, for each), those with tumor stages III and IV (P= 0.008, 0.002 and < 0.001 respectively), and those with LN metastasis (P< 0.001, for each). Moreover, there was a statistically significant upregulation in CXCL-12 gene expression among PTC cases with extra-thyroid extension (P< 0.001).

CONCLUSION

mRNA expression of TROP-2, SPL-2, and CXCL12 among PTC cases increased in larger tumor size, tumor stages III and IV, and LN metastasis. Moreover, there was an increase in CXCL-12 gene expression among PTC cases with extra-thyroid extension. Thus, TROP-2, SPL-2, and CXCL12 expressions could be possible diagnostic and prognostic markers in PTC.

Association of Ultrasonography Features of Follicular Thyroid Carcinoma With Tumor Invasiveness and Prognosis Based on WHO Classification and TERT Promoter Mutation

OBJECTIVE

To investigate the association of ultrasound (US) features of follicular thyroid carcinoma (FTC) with tumor invasiveness and prognosis based on the World Health Organization (WHO) classification and telomerase reverse transcriptase (TERT) promoter mutations.

MATERIALS AND METHODS

This retrospective study included 54 surgically confirmed FTC patients with US images and TERT promoter mutations (41 females and 13 males; median age [interquartile range], 40 years [30-51 years]). The WHO classification consisted of minimally invasive (MI), encapsulated angioinvasive (EA), and widely invasive (WI) FTCs. Alternative classifications included Group 1 (MI-FTC and EA-FTC with wild type TERT), Group 2 (WI-FTC with wild type TERT), and Group 3 (EA-FTC and WI-FTC with mutant TERT). Each nodule was categorized according to the US patterns of the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and American College of Radiology-TIRADS (ACR-TIRADS). The Jonckheere-Terpstra and Cochran-Armitage tests were used for statistical analysis.

RESULTS

Among 54 patients, 29 (53.7%) had MI-FTC, 16 (29.6%) had EA-FTC, and nine (16.7%) had WI-FTC. In both the classifications, lobulation, irregular margins, and final assessment categories showed significant differences (all Ps ≤ 0.04). Furthermore, the incidences of lobulation, irregular margin, and high suspicion category tended to increase with increasing tumor invasiveness and worse prognosis (all Ps for trend ≤ 0.006). In the WHO groups, hypoechogenicity differed significantly among the groups (P = 0.01) and tended to increase in proportion as tumor invasiveness increased (P for trend = 0.02). In the alternative group, punctate echogenic foci were associated with prognosis (P = 0.03, P for trend = 0.03).

CONCLUSION

Increasing tumor invasiveness and worsening prognosis in FTC based on the WHO classification and TERT promoter mutation results were positively correlated with US features that indicate malignant probability according to both K-TIRADS and ACR-TIRADS.

Investigation of pre-operative demographic, biochemical, sonographic and cytopathological findings in low-risk thyroid neoplasms

OBJECTIVE

The present article analyses pre-operative demographic, biochemical, sonographic and histopathological characteristics of low-risk thyroid neoplasms (LRTNs), with a focus on four subgroups, "well-differentiated carcinoma-not otherwise specified" (WDC-NOS), "non-invasive follicular thyroid neoplasm with papillary like nuclear features" (NIFTP), "well-differentiated tumours of uncertain malignant potential" (WDT-UMP) and "follicular tumour of uncertain malignant potential" (FT-UMP).

METHODS

The study retrospectively analyzed the histopathology of 2453 malignant thyroids and the final analyses included 99 cases diagnosed with LRTNs. The demographic and clinical features, pre-operative thyroid function, ultrasonography results, cytopathology results, histopathology results and prognostic classifications were assessed.

RESULTS

The groups were similar demographic characteristics and the majority of clinical data, including comorbidities, thyroid function tests, thyroid cancer/neck radiotherapy history. NIFTPs represented 69.7% of all LRTNs. All (100%) WDT-UMPs had solitary nodules. Index nodule volume differed among the groups (p = .036), it was the lowest in WDC-NOS [0.68 (0.63-0.72 cc)] and highest in FT-UMP [12.6 (0.5-64 cc)]. Echogenicity findings were similar. Index nodule TIRADS demonstrated a significant difference (p = .021) but index nodule halo sign and BETHESDA scores were similar in all groups. The diameter, localisation and multicentric structure of LRTNs were again similar for all groups. Finally, prognostic scores suggested similar outcomes in all groups.

CONCLUSION

The majority of LRTNs were NIFTPs in our population and all WDT-UMPs were solitary lesions. Index nodule volume was the most essential discriminating sonographic finding but further research must be performed before discriminatory potential can be described.

Alterations in the amino acid profile in patients with papillary thyroid carcinoma with and without Hashimoto's thyroiditis

Purpose

Amino acids (AAs) play important physiological roles in living cells. Some amino acid changes in blood are specific for autoimmune disorders, and some are specific for thyroid cancer. The aims of this study were to profile AA metabolites in the serum of patients with papillary thyroid carcinoma (PTC0) without Hashimoto's thyroiditis (HT) and patients with PTC with HT (PTC1) and predict whether AA metabolites are associated with thyroid disease, thyroid hormone and thyroid autoantibodies.

Methods

A total of 95 serum samples were collected, including 28 healthy controls (HCs), 28 PTC0 patients and 39 PTC1 patients. Serum samples were analyzed by high-performance liquid chromatography-triple stage quadrupole-mass spectrometry (HPLC-TSQ-MS), and twenty-one amino acids (AAs) were detected.

Results

The serum concentration of glutamic acid was significantly elevated in PTC1 patients compared with PTC0 patients. Lysine was the second amino acid that differentiated these two groups of PTC patients. In addition, the serum concentrations of glycine, alanine and tyrosine were significantly reduced in both PTC patient groups compared to the HC group. These AAs were also correlated with thyroid hormones and antibodies. Five amino acid markers, namely, glycine, tyrosine, glutamic acid, glutamine and arginine, separated/distinguished PTC0 patients from healthy subjects, and eight AA markers, the same AAs as above without arginine but with alanine, leucine, valine and histidine, separated/distinguished PTC1 patients from healthy subjects based on ROC analysis.

Conclusion

Compared with the HCs, changes in AAs in PTC0 and PTC1 patients showed similar patterns, suggesting the possibility of a common pathophysiological basis, which confirms preliminary research that PTC is significantly associated with pathologically confirmed HT. We found two AAs, lysine and alanine, that can perform diagnostic functions in distinguishing PTC1 from PTC0.

A study to evaluate association of nuclear grooving in benign thyroid lesions with RET/PTC1 and RET/PTC3 gene translocation

INTRODUCTION

Papillary thyroid carcinoma (PTC) is the most common malignant lesion of the thyroid characterized by unique histological features like nuclear grooving, nuclear clearing, and intra-nuclear inclusions. However, nuclear grooves are observed even in benign thyroid lesions (BTL) like nodular goiter (NG), Hashimoto's thyroiditis (HT), and follicular adenoma (FA) resulting in diagnostic dilemma of the presence of PTC in such BTL. RET/PTC gene translocation is one of the most common oncogenic rearrangements seen in PTC, known to be associated with nuclear grooving. Among different types of RET/PTC translocations, RET/PTC1 and RET/PTC3 gene translocations are the most common types. These translocations have also been identified in many BTL like hyperplastic nodules and HT. Our study aimed to determine the frequency of nuclear grooving in BTL and evaluate their association with RET/PTC1 and RET/PTC3 gene translocation.

METHODS

Formalin-fixed, paraffin-embedded (FFPE) tissue blocks of NG, HT, and FA were included in the study. The hematoxylin and eosin (H&E) stained sections were evaluated for the presence of nuclear grooving/high power field (hpf) and a scoring of 0 to 3 was used for the number of grooves. Sections of 10 μ thickness were cut and the cells containing the nuclear grooves were picked using Laser-Capture microdissection. About 20 to 50 such cells were microdissected in each of the cases followed by RNA extraction, cDNA conversion, realtime-polymerase chain reaction (RQ-PCR) for RET/PTC1 and RET/PTC3 gene translocation, and the findings were analyzed for statistical significance.

RESULTS

Out of 87 BTL included in the study, 67 (77.0%) were NG, 12 (13.7%) were HT, and 8 (9.2%) were FA. Thirty-two cases (36.8%) had nuclear grooving with 18 out of 67 NG, 6 out of 12 HT, and all 8 cases of FA showing a varying number of nuclear grooves. A significant association between the number of nuclear grooves with RET/PTC gene translocation (p-value of 0.001) was obtained. A significant association of HT with RET/PTC gene translocation (p-value of 0.038) was observed. RET/PTC1 and RET/PTC3 translocation were seen in 5 out of 87 cases, with HT showing positivity in 2 and FA in 1 case for RET/PTC1 and HT in 1 and FA in 2 cases for RET/PTC3 gene translocation with 1 case of FA being positive for both RET/PTC1 and RET/PTC3 gene translocation.

CONCLUSIONS

The frequency of nuclear grooving among BTLs in our study was 36.8%. Our study shows, that when BTLs, show nuclear grooves, with an increase in the nuclear size, oval and elongated shape, favors the possibility of an underlying genetic aberration like RET/PTC gene translocation, which in turn supports the reporting pathologist to suggest a close follow up of the patients on seeing such nuclear features on cytology or histopathology sample, particularly in HT.

Molecular profile of follicular tumors of the thyroid gland

More than 90 % of newly diagnosed cases of endocrine cancer occur in the thyroid gland. Introduction of fine needle puncture of the thyroid gland, with the classification of cytological material according to the Bethesda system, has become the cornerstone of the diagnosis of malignant neoplasms of the thyroid gland. However, traditionally in this classification there remains a weak link called a follicular tumor (category IV). The detection of a follicular tumor in the cytological material does not allow one to reliably classify the mass as benign or malignant and requires surgical intervention with morphological verification. In recent years, the possibilities of molecular genetic testing have improved markedly. Follicular tumors tend to accumulate mutations, which over time can lead to malignant transformation, but can also be used as a method of timely diagnosis. This review analyzes the literature on the possibilities of molecular genetic testing in assessing the malignant potential of follicular formations of the thyroid gland.

The First Case of Cribriform-Morular Thyroid Carcinoma and FAP with APC Gene Mutation in China: A Case Report and Brief Review

The cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC) is now designated as morular cribriform thyroid carcinoma (CMTC) according to the 5^th edition of the World Health Organization (WHO) Classification of Thyroid Tumors. CMTC can appear within a familial adenomatous polyposis (FAP) or be sporadic. We report the first case of a young female patient in China who was diagnosed with FAP and CMTC with a mutation in exon 16 of the APC gene underlying the disease. The main purpose of this case report is to provide a special pathological type of thyroid tumors, which is expected to be helpful for clinical work in the future.

Unexpected Widespread Bone Metastases from a BRAF K601N Mutated Follicular Thyroid Carcinoma within a Previously Resected Multinodular Goiter

Follicular thyroid carcinoma (FTC) represents the second most common malignant thyroid neoplasm after papillary carcinoma (PTC). FTC is characterized by the tendency to metastasize to distant sites such as bone and lung. In the last 20 years, the understanding of the molecular pathology of thyroid tumors has greatly improved. Uncommon BRAF non-V600E mutations have been identified and are generally believed to associate with follicular patterned tumors of low malignant potential, particularly non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTPs) (i.e., non-invasive encapsulated follicular variant PTC). We here report for the first time widespread bone metastases from a BRAF K601N mutated follicular tumor.

EIF1AX mutation in thyroid tumors: a retrospective analysis of cytology, histopathology and co-mutation profiles

Background

The EIF1AX mutation has been identified in various benign and malignant thyroid lesions, with a higher prevalence in poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma, especially when combined with RAS or TP53 mutation. However, data and clinical significance of EIF1AX mutations in thyroid nodules is still limited. We investigated the prevalence of EIF1AX mutations and co-mutations in cytologically indeterminate thyroid nodules at our institution.

Methods

A 5-year retrospective analysis was performed on surgically resected thyroid nodules with identified EIF1AX mutations on molecular testing with ThyroseqV3®. Mutation type and presence of co-mutations were correlated with histopathologic diagnosis and clinical characteristics. Histopathology diagnoses were subsequently categorized as benign, borderline, malignant or aggressive malignant (≥ 10% PDTC component). Chi-square test was used to compare the malignancy associations of the: 1) A113_splice mutation compared to non-A113_splice mutations 2) singular A113_splice mutations compared to singular non-A113_splice mutations. Fisher’s Exact Test was used to determine the association of A113_splice mutation with aggressive malignancies compared to non-A113_splice mutations. A p value of 0.05 or less was considered statistically significant.

Results

Out of 1583 patients who underwent FNA, 621 had further molecular testing. 31 cases (5%) harbored EIF1AX mutations. Of these cases, 12 (38.7%) were malignant, 2 (6.5%) were borderline, and 17 (55%) were benign. 4/31 cases (13%) were aggressive malignant (≥ 10% PDTC component). The most prevalent mutation was the A113_splice mutation at the junction of intron 5 and exon 6 (48%). All other mutations, except one, were located at the N-terminal in exon 2. 7/31 cases (22.6%) harbored ≥ 1 co-mutation(s), including 4 RAS, 3 TP53, 1 TERT and 1 PIK3CA, with 86% of them being malignant. All 4 nodules with RAS co-mutations were malignant including one PDTC.

Conclusion

Our study reports the largest cohort of EIF1AX mutations in Bethesda III/IV FNA samples with surgical follow-up to our knowledge. The presence of the EIF1AX mutation confers a 45.2% risk of malignancy (ROM) or borderline after surgery. However, the coexistence of EIF1AX mutations with other driver mutations such as RAS, TERT or TP53 conferred an 86% ROM. While 55% of thyroid nodules were benign at the time of surgery, the possible malignant transformation of these nodules, had they not been resected, is unknown. Finally, 13% of the nodules with EIF1AX mutations were aggressive with a significant PDTC component. These findings can further aid in clinical decisions for patients with thyroid nodules.

Graphic Abstract

Update from the 2022 World Health Organization Classification of Thyroid Tumors: A Standardized Diagnostic Approach

The fifth edition of the World Health Organization (WHO) histologic classification of thyroid neoplasms released in 2022 includes newly recognized tumor types, subtypes, and a grading system. Follicular cell-derived neoplasms are categorized into three families (classes): benign tumors, low-risk neoplasms, and malignant neoplasms. The terms "follicular nodular disease" and "differentiated high-grade thyroid carcinoma" are introduced to account for multifocal hyperplastic/neoplastic lesions and differentiated thyroid carcinomas with high-grade features, respectively. The term "Hürthle cells" is replaced with "oncocytic cells." Invasive encapsulated follicular and cribriform morular variants of papillary thyroid carcinoma (PTC) are now redefined as distinct tumor types, given their different genetic alterations and clinicopathologic characteristics from other PTC subtypes. The term "variant" to describe a subclass of tumor has been replaced with the term "subtype." Instead, the term "variant" is reserved to describe genetic alterations. A histologic grading system based on the mitotic count, necrosis, and/or the Ki67 index is used to identify high-grade follicular-cell derived carcinomas and medullary thyroid carcinomas. The 2022 WHO classification introduces the following new categories: "salivary gland-type carcinomas of the thyroid" and "thyroid tumors of uncertain histogenesis." This review summarizes the major changes in the 2022 WHO classification and their clinical relevance.

Burden of thyroid cancer in North Africa and Middle East 1990–2019

Background

Thyroid cancer is the leading cause of mortality and morbidity among cancers of the endocrine system. We aimed to describe the trends of thyroid cancer burden in North Africa and Middle East for 1990–2019.

Methods

Data on burden of thyroid cancer in North Africa and Middle East from 1990 to 2019 were obtained from the Global Burden of Disease (GBD) Study 2019. Decomposition analysis was used to estimate the effects of population growth, aging, and change in incident numbers on overall change of thyroid cancer incidence. Also, we used the comparative risk assessment framework of GBD to determine the burden of thyroid cancer attributable to a high body mass index (BMI).

Results

In 2019, the age-standardized incidence rate (ASIR) and age-standardized mortality rate (ASMR) of thyroid cancer were 3.5 (2.9–4) and 0.5 (0.5–0.7) per 100,000, respectively. The highest age-standardized incidence, deaths, and disability-adjusted life year (DALY) rate were in Lebanon, Afghanistan, and United Arab Emirates, respectively. The ASIR of thyroid cancer in region was about 2.5 times higher among women, which had a positive association with increasing age. In 2019, the age-standardized deaths attributable to a high BMI was 16.7% of all deaths due to thyroid cancer. In 1990–2019, the overall change in thyroid cancer incident cases was a 396% increase which was mostly driven by the increase in disease-specific incidence rate (256.8%).

Conclusions

Women, the elderly above about 60 years old, and countries with a higher sociodemographic index showed higher incidence rates of thyroid cancer. Regarding our findings, it is recommended to establish preventive plans by modification in life style like weight reduction programs.

Long-Term Exposure to Decabromodiphenyl Ether Promotes the Proliferation and Tumourigenesis of Papillary Thyroid Carcinoma by Inhibiting TRß

Simple Summary

PBDEs have been reported to have endocrine-disrupting and tumour-promoting activity; however, the effects of BDE209 (the highest brominated PBDEs) on the thyroid and the underlying mechanisms are unclear. In this study, we found that long-term exposure to BDE209 could cause chronic toxicity and potential tumourigenesis by inhibiting the expression and function of TRß, which induces the proliferation of thyroid tissue and the oncogenesis of thyroid carcinoma. These findings emphasize the damaging effects that exposure to BDE209 has on human thyroid and papillary thyroid carcinoma.

Abstract

Polybrominated diphenyl ethers (PBDEs) have been reported to possess endocrine-disrupting and tumour-promoting activity. However, the effects of long-term exposure to decabromodiphenyl ether (BDE209) on thyroid tumourigenesis of papillary thyroid carcinoma (PTC) and the underlying mechanisms remain poorly defined. In this study, functional assays in vitro and mouse models in vivo were used to evaluate the toxic effects of long-term exposure to environmental concentrations of BDE209 on the pathogenesis and progression of PTC. MTS, EdU and colony-forming assays confirmed the chronic toxicity of BDE209 on the proliferation of human normal follicular epithelial cell line (Nthy-ori 3-1) and PTC-derived cell lines (TPC-1 and BCPAP). Wound and Transwell assays showed that BDE209 exacerbated the aggressiveness of PTC cells. BDE209 significantly promoted cell proliferation during the S and G2/M phases of the cell cycle. Mechanistically, BDE209 altered the thyroid system by acting as a competitive inhibitor of thyroid receptor beta (TRß) expression and function, which was further proven by public databases and RNA-seq bioinformation analysis. Taken together, these results demonstrated that BDE209 has chronic toxicity and potential tumourigenic effects on the thyroid by inhibiting TRß.

Ultrasonographic characteristics of Hurthle cell: prediction of malignancy

Purpose

This study investigated the ultrasound (US) features of malignancy in patients with Hürthle cell neoplasms (HCNs) of the thyroid gland.

Methods

The present study included 139 HCNs that had undergone surgical excision at a single institution from 1996 to 2020 and had preoperative US images. The sonographic characteristics of HCNs were correlated with their pathological results. The US findings associated with malignancy were explored using logistic regression analysis, and the diagnostic performance and cutoff were assessed using receiver operating characteristic analysis.

Results

The most common US findings of HCNs were a solid content (76.3%), oval to round shape (100%), hypoechogenicity (70.5%), a smooth margin (95.0%), the halo sign (90.6%), and no calcifications (93.5%). HCNs were commonly smaller in pathologic measurements than in US measurements (smaller, same, and greater than US measurements in 60.4%, 21.6%, and 18.0% of HCNs, respectively; P<0.001). On US, malignant nodules were significantly larger than benign nodules (3.4±1.6 cm vs. 2.2±1.2 cm, P<0.001). Multiple logistic regression showed that the US tumor size was an independent predictor of malignancy (P=0.001; odds ratio, 1.730 for a 1-cm increase [95% confidence interval, 1.258 to 2.375]). The best cutoff US tumor size for predicting malignancy was 3.35 cm (sensitivity, 53.1%; specificity, 87.9%).

Conclusion

The US tumor size was found to be an independent predictor of malignancy in HCNs, and a US tumor size >3.35 cm might be used as a criterion to suggest malignancy. The size of HCNs often showed discrepancies between US and pathologic measurements.

Feasibility of Recombinant Human TSH as a Preparation for Radioiodine Therapy in Patients with Distant Metastases from Papillary Thyroid Cancer: Comparison of Long-Term Survival Outcomes with Thyroid Hormone Withdrawal

Background: this study was designed to compare the long-term survival outcomes of patients prepared for radioiodine (RAI) therapy using either thyroid hormone withdrawal (THW) or recombinant human thyrotropin (rhTSH) stimulation, by specifically focusing on cases with distant metastases from papillary thyroid cancer (PTC). Methods: A retrospective analysis was performed on 88 patients with distant metastases from PTC. Fifty-one and thirty-seven patients were prepared for RAI treatment by either THW or rhTSH stimulation, respectively. The primary endpoints were progression-free survival (PFS) and disease-specific survival (DSS). Results: The 10-year DSS rates of patients prepared for RAI therapy using either THW or rhTSH stimulation were 62.2% and 73.3%, respectively. Using multivariate analysis, RAI-avid metastases (p = 0.025) and preparation with rhTSH (p = 0.041) were identified as independent prognostic factors for PFS. Notably, PFS in the group of patients with RAI-avid metastases and preparation with rhTSH was significantly better than that in the other groups (p = 0.025). Conclusions: Preparation for RAI therapy using rhTSH stimulation is not inferior to THW preparation in terms of long-term survival outcomes experienced by patients with PTC and distant metastasis. Patients with RAI-avid metastases and preparation with rhTSH had the most favorable PFS.

Age, American Thyroid Association Risk Group, and Response to Therapy Are Prognostic Factors in Children With Differentiated Thyroid Cancer

CONTEXT

Against the background of increasing incidence, pediatric differentiated thyroid carcinoma (DTC) frequently presents with advanced disease and high recurrence rates while prognosis remains excellent.

BACKGROUND

We investigated the use of a pediatric classification and an adult response to therapy risk stratification for pediatric DTC patients and their implications for adaptation of treatment and follow-up.

METHODS

Data from patients aged <18 years with a diagnosis of primary DTC, registered with the German Pediatric Oncology Hematology-Malignant Endocrine Tumor registry since 1995, were analyzed. For risk prediction, patients were retrospectively assigned to the American Thyroid Association (ATA) risk groups and evaluated for response to therapy.

RESULTS

By October 2019, 354 patients with DTC had been reported (median age at diagnosis 13.7 years, range 3.6-17.9) with lymph node and distant metastases in 74.3% and 24.5%. Mean follow-up was 4.1 years (range 0-20.6). Ten-year overall and event-free survival (EFS) rates were 98.9% and 78.1%. EFS was impaired for patients with lymph node and distant metastases (P < .001), positive postoperative thyroglobulin (P = .006), incomplete resection (P = .002), sequential surgeries to achieve total thyroidectomy (P = .042), invasion of capsule (P < .001) and lymph vessels (P = .005), infiltration of surrounding soft tissues (P < .001), tumor multifocality (P < .001), ATA intermediate- and high-risk group (P < .001), and age <10 years (P < .001). Multivariate analysis revealed age <10 years at diagnosis, ATA high-risk level, and poor response to therapy as significant negative prognostic factors for EFS.

CONCLUSION

Age, ATA risk group, and response to therapy emerged as significant prognostic factors for EFS in pediatric patients with DTC, requiring risk-adapted individualized therapy and follow-up.

Molecular classification of follicular thyroid carcinoma based on TERT promoter mutations

Follicular thyroid carcinoma (FTC) has different clinicopathological characteristics than papillary thyroid carcinoma. However, there are no independent systems to predict cancer-specific survival (CSS) in FTC. Telomerase reverse transcriptase (TERT) promoter mutations are associated with tumor aggressiveness. Thus, it could be a potential prognostic marker. The aim of this study was to refine the CSS risk prediction using TERT promoter mutations in combination with the fourth edition of World Health Organization (WHO 2017) morphological classification. We investigated 77 FTC patients between August 1995 and November 2020. Cox regression was used to calculate hazard ratios to derive alternative groups. Disease-free survival (DFS) and CSS predictability were compared using Proportion of variation explained (PVE) and C-index. CSS was significantly different in encapsulated angioinvasive (EA)-FTC patients stratified by TERT promoter mutations [wild-type (WT-TERT) vs. mutant (M-TERT); P < 0.001] but not in minimally invasive (MI)-FTC and widely invasive (WI)-FTC patients (P = 0.691 and 0.176, respectively). We defined alternative groups as follows: Group 1 (MI-FTC with WT-TERT and M-TERT; EA-FTC with WT-TERT), Group 2 (WI-FTC with WT-TERT), and Group 3 (EA-FTC with M-TERT; WI-FTC with M-TERT). Both PVE (22.44 vs. 9.63, respectively) and C-index (0.831 vs. 0.731, respectively) for CSS were higher in the alternative groups than in the WHO 2017 groups. Likewise, both PVE (27.1 vs. 14.9, respectively) and C-index (0.846 vs. 0.794, respectively) for DFS were also higher in the alternative groups than in the WHO 2017 groups. Alternative group harmonizing of the WHO 2017 classification and TERT promoter mutations is effective in predicting CSS in FTC patients, thereby improving DFS predictability.

Hobnail variant of papillary thyroid carcinoma with anaplastic dedifferentiation co-existent with tuberculosis lymphadenitis

Introduction

The current study aims to report a rare case of metastatic papillary thyroid carcinoma (PTC) of the cervical lymph nodes with hobnail variant and anaplastic de-differentiation. In addition to the primary disease, there was a second pathology which was caseating granulomatous lymph adenitis suggestive of tuberculosis.

Case report

A 91-year-old female presented with a painful right sided neck swelling for two weeks, increased in size suddenly. On clinical examination, there was a well-defined firm painful right sided neck mass. On ultrasound examination, there was multiple well defined solid hypoechoic, hypervascular nodules. These resembled lymph nodes of variable size and shape, mostly in the right side. The patient underwent right lateral cervical lymph node dissection. After the operation, she was sent for radiotherapy.

Discussion

The hobnail variant of PTC is genetically identical to poorly differentiated thyroid carcinoma in that its mutations are in the p53 and TERT promoters are more common in this variant than in conventional PTCs. The proportion of hobnail features have no effect on the outcome. Additionally, 10% of tumor cells with hobnail features were previously linked to a more aggressive clinicopathological aspect.

Conclusion

Although it is rare, metastatic PTC with hobnail variant could undergo anaplastic dedifferentiation.

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Thyroid carcinoma accounts for nearly 1% of all malignancies.

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The hobnail variant of papillary thyroid carcinoma (HPTC) is a rare condition.

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Anaplastic thyroid carcinoma (ATC) is a rare form of thyroid cancer.

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Malignant lesions and tuberculosis coexisting at the same site is exceedingly unusual.

Emerging Biomarkers in Thyroid Practice and Research

Simple Summary

Tumor biomarkers are molecules at genetic or protein level, or certain evaluable characteristics. These help in perfecting patient management. Over the past decade, advanced and more sensitive techniques have led to the identification of many new biomarkers in the field of oncology. A knowledge of the recent developments is essential for their application to clinical practice, and furthering research. This review provides a comprehensive account of such various markers identified in thyroid carcinoma, the most common endocrine malignancy. While some of these have been brought into use in routine patient management, others are novel and need more research before clinical application.

Abstract

Thyroid cancer is the most common endocrine malignancy. Recent developments in molecular biological techniques have led to a better understanding of the pathogenesis and clinical behavior of thyroid neoplasms. This has culminated in the updating of thyroid tumor classification, including the re-categorization of existing and introduction of new entities. In this review, we discuss various molecular biomarkers possessing diagnostic, prognostic, predictive and therapeutic roles in thyroid cancer. A comprehensive account of epigenetic dysregulation, including DNA methylation, the function of various microRNAs and long non-coding RNAs, germline mutations determining familial occurrence of medullary and non-medullary thyroid carcinoma, and single nucleotide polymorphisms predisposed to thyroid tumorigenesis has been provided. In addition to novel immunohistochemical markers, including those for neuroendocrine differentiation, and next-generation immunohistochemistry (BRAF V600E, RAS, TRK, and ALK), the relevance of well-established markers, such as Ki-67, in current clinical practice has also been discussed. A tumor microenvironment (PD-L1, CD markers) and its influence in predicting responses to immunotherapy in thyroid cancer and the expanding arena of techniques, including liquid biopsy based on circulating nucleic acids and plasma-derived exosomes as a non-invasive technique for patient management, are also summarized.

Risk Factors for Recurrence of Follicular Thyroid Cancer: A Systematic Review

Background: In risk assessment of recurrence, papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC) are often grouped together as differentiated thyroid cancer (DTC). However, while risk factors affecting recurrence of PTC are well established, risk factors for recurrence of FTC are not. This systematic review examines risk factors for recurrence of FTC and evaluates their significance. Methods: A systematic search on PubMed and Embase was performed in September 2020, including studies evaluating risk factors for recurrence of FTC. A quality assessment of the enrolled studies was performed. Results: Nine studies (n = 1544 patients) from eight countries were included. The average recurrence rate was 13.6%, and distant metastasis (DM) constituted 64.8% of the recurrent cases. The risk factors examined were sex, age at diagnosis, primary tumor size, degree of invasiveness, focality, positive resection margin, lymph node (LN) metastasis, and DM at diagnosis. Risk factors correlated with recurrence of FTC were age older than 45 years, primary tumor size above 40 mm, widespread invasion, multifocality, positive resection margin, LN metastasis, and DM at diagnosis. Sex was not a statistically significant risk factor. Conclusions: We identified seven risk factors associated with recurrence of FTC. Age and multifocality were found to be of greater impact regarding recurrence risk of FTC compared with PTC. Future research needs to address the impact of different risk factors for recurrence of FTC particularly including age, primary tumor size, angioinvasion, and mutational status.

Role of Advanced Glycation End-Products and Other Ligands for AGE Receptors in Thyroid Cancer Progression

To date, thyroid cancers (TCs) remain a clinical challenge owing to their heterogeneous nature. The etiopathology of TCs is associated not only with genetic mutations or chromosomal rearrangements, but also non-genetic factors, such as oxidative-, nitrosative-, and carbonyl stress-related alterations in tumor environment. These factors, through leading to the activation of intracellular signaling pathways, induce tumor tissue proliferation. Interestingly, the incidence of TCs is often coexistent with various simultaneous mutations. Advanced glycation end-products (AGEs), their precursors and receptors (RAGEs), and other ligands for RAGEs are reported to have significant influence on carcinogenesis and TCs progression, inducing gene mutations, disturbances in histone methylation, and disorders in important carcinogenesis-related pathways, such as PI₃K/AKT/NF-kB, p21/MEK/MPAK, or JAK/STAT, RAS/ERK/p53, which induce synthesis of interleukins, growth factors, and cytokines, thus influencing metastasis, angiogenesis, and cancer proliferation. Precursors of AGE (such as methylglyoxal (MG)) and selected ligands for RAGEs: AS1004, AS1008, and HMGB1 may, in the future, become potential targets for TCs treatment, as low MG concentration is associated with less aggressive anaplastic thyroid cancer, whereas the administration of anti-RAGE antibodies inhibits the progression of papillary thyroid cancer and anaplastic thyroid cancer. This review is aimed at collecting the information on the role of compounds, engaged in glycation process, in the pathogenesis of TCs. Moreover, the utility of these compounds in the diagnosis and treatment of TCs is thoroughly discussed. Understanding the mechanism of action of these compounds on TCs pathogenesis and progression may potentially be the grounds for the development of new treatment strategies, aiming at quality-of-life improvements.

How to identify indolent thyroid tumors unlikely to recur and cause cancer death immediately after surgery-Risk stratification of papillary thyroid carcinoma in young patients

Current histopathological diagnosis methods cannot distinguish the two types of thyroid carcinoma: clinically significant carcinomas with a potential risk of recurrence, metastasis, and cancer death, and clinically insignificant carcinomas with a slow growth rate. Both thyroid tumors are diagnosed as "carcinoma" in current pathology practice. The clinician usually recommends surgery to the patient and the patient often accepts it because of cancer terminology. The treatment for these clinically insignificant carcinomas does not benefit the patient and negatively impacts society. The author proposed risk stratification of thyroid tumors using the growth rate (Ki-67 labeling index), which accurately differentiates four prognostically relevant risk groups based on the Ki-67 labeling index, ≥30%, ≥10 and <30%, >5 and <10%, and ≤5%. Indolent thyroid tumors with an excellent prognosis have the following four features: young age, early-stage (T1-2 M0), curatively treated, and low proliferation index (Ki-67 labeling index of ≤5%), and are unlikely to recur, metastasize, or cause cancer death. Accurate identification of these indolent tumors helps clinicians select more conservative treatments to avoid unnecessary aggressive (total thyroidectomy followed by radio-active iodine) treatments. Clinicians can alleviate the fears of patients by confirming these four features, including the low proliferation rate, in a pathology report immediately after surgery when patients are most concerned.

Thyroid Warthin-Like Cancer Concurrent With Multiple Sclerosis: A Case Report

Warthin like-papillary thyroid cancer (WL-PTC) is a rare malignancy; it is difficult to distinguish preoperatively a WLPTC from a classic PTC. Often it is associated with Hashimoto thyroiditis (HT) that determines a better prognosis with a very low probability of recurrence. The case concerns a 43-year-old female with a single thyroid nodule suspected for cancer; and she had multiple sclerosis (MS) from the age of 19. Thyroid hormone levels were normal such as thyroid antibodies. Total thyroidectomy with lymphadenectomy of central compartment was performed. Histological examination revealed a Warthin like-PTC without Hashimoto thyroiditis. The mechanisms involved in pathogenesis of thyroid cancer in patients with autoimmune disease are not completely clear. We hypothesized that not only a local autoimmune response, such as HT, could contribute to the determination of this type of cancer but also a systemic autoimmune disease such as MS.

Imaging of the Thyroid: Practical Approach

Imaging evaluation of the thyroid gland spans a plethora of modalities, including ultrasound imaging, cross-sectional studies, and nuclear medicine techniques. The overlapping of clinical and imaging findings of benign and malignant thyroid disease can make interpretation a complex undertaking. We aim to review and simplify the vast current literature and provide a practical approach to the imaging of thyroid disease for application in daily practice. Our approach highlights the keys to differentiating and diagnosing common benign and malignant disease affecting the thyroid gland.

Clinicopathological Characteristics and Recurrence-Free Survival of Rare Variants of Papillary Thyroid Carcinomas in Korea: A Retrospective Study

BACKGROUND

We aimed to evaluate the clinicopathological features and biological behaviors of Korean thyroid cancer patients with rare variants of papillary thyroid carcinoma (PTC) to address the ambiguity regarding the prognostic consequences of these variants.

METHODS

We retrospectively reviewed the medical records of 5,496 patients who underwent thyroid surgery for PTC, between January and December 2012, in nine tertiary hospitals. Rare PTC variants included tall cell (TCV), columnar cell (CCV), diffuse sclerosing (DSV), cribriform-morular (CMV), solid (SV), hobnail, and Warthin-like variants. Recurrence-free survival (RFS) was defined as the time from the date of thyroidectomy until recurrence.

RESULTS

Rare variants accounted for 1.1% (n=63) of the PTC patients; with 0.9% TCV, 0.02% CCV, 0.1% DSV, 0.1% CMV, and 0.1% SV. The mean age of patients and primary tumor size were 42.1±13.1 years and 1.3±0.9 cm, respectively. Extrathyroidal extension and cervical lymph node metastasis were observed in 38 (60.3%) and 37 (58.7%) patients, respectively. Ultrasonographic findings revealed typical malignant features in most cases. During a median follow-up of 7 years, 6.3% of patients experienced a locoregional recurrence. The 5-year RFS rates were 71.4% in patients with DSV or SV, 95.9% for TCV, or CCV, and 100% for other variants. DSV emerged an independent risk factor associated with shorter RFS.

CONCLUSION

In this multicenter Korean cohort, rare variants accounted for 1.1% of all PTC cases, with TCV being the most frequent subtype. DSV emerged as a significant prognostic factor for RFS.

A case report of simultaneous medullary and papillary carcinoma of thyroid

Objective. Medullary (MTC) and papillary (PTC) thyroid carcinoma are two different types of thyroid carcinoma with significant differences in origin. Their co-occurrence in a patient is a rare phenomenon. We report a patient with simultaneous presentation of both MTC and PTC. Case presentation. A 62-year-old euthyroid woman with a cervical mass was evaluated, underwent total thyroidectomy, and neck dissection. The examination revealed a MTC large nodule as well as a small nodule of the tall cell variant of PTC, along with the concomitant cervical lymph node metastases. Subsequently, the genetic analysis showed BRAF mutations. Adjuvant treatments including radioiodine and thyroid hormone replacement therapies were performed for the patient. Conclusions. The cooccurrence of MTC and PTC in the same patient is a rare phenomenon. The clinical manifestations and biological behavior of these cancers are completely different. Since the therapeutic strategy and prognosis are very different in these patients, accurate diagnosis of this coexistence is very important.

CD73 expression in normal, hyperplastic, and neoplastic thyroid: a systematic evaluation revealing CD73 overexpression as a feature of papillary carcinomas

CD73 converts AMP to adenosine, an immunosuppressive metabolite that promotes tumorigenesis. This study presents a systematic evaluation of CD73 expression in benign, hyperplastic, and neoplastic thyroid. CD73 expression was assessed by immunohistochemistry in 142 thyroid samples. CD73 was expressed in normal thyroid (3/6) and goiter (5/6), with an apical pattern and mild intensity. Apical and mild CD73 expression was also present in oncocytic cell adenomas/carcinomas (9/10; 5/8) and in follicular adenomas/carcinomas (12/18; 23/27). In contrast, papillary thyroid carcinomas featured extensive and intense CD73 staining (49/50) (vs. normal thyroid/goiter, p < 0.001). Seven of nine anaplastic carcinomas were CD73-positive with heterogeneous extensiveness of staining. Medullary and poorly differentiated carcinomas were mostly CD73-negative (1/6; 2/2). These results were corroborated by NT5E mRNA profiling. Papillary carcinomas feature enhanced CD73 protein and mRNA expression with distinct and intense staining, more pronounced in the invasive fronts of the tumors.

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.

Impact of pregnancy on papillary thyroid carcinoma prognosis

Introduction

thyroid carcinoma is more frequent in women of reproductive age. It can affect both fertility and the course of pregnancy. The aim of the study was to investigate the influence of pregnancy as a factor of recurrence or progression, on the prognosis of thyroid carcinoma.

Methods

we conducted a retrospective cohort study of 117 young female patients followed up for papillary thyroid carcinoma (PTC) at the Department of Endocrinology, Diabetology and Metabolic Diseases of Ibn Rochd University Hospital of Casablanca, from January 2010 to December 2018, divided into 2 groups: group 1 composed of pregnant patients (n=42) and group 2 being the control group (n=75). Statistical analysis was made using SPSS software version 22.0.0.

Results

average age of pregnant patients was 35 ± 6.5 years old. Mean duration between first pregnancy and treatment completion was 4.4 ± 3.1 years. Over an average treatment duration of 14.4 months in postpartum, 30 patients were in remission (thyroglobulin (Tg) <1μg/l, negative thyroglobulin antibody and no morphological abnormality), while 12 had persistent symptoms (detectable Tg/thyroglobulin antibody and/or morphological abnormality). Thyroid stimulating hormone (TSH) during pregnancy was on average 0.83 mIU/l. Cancer progression was correlated with persistence of thyroid cancer to treatment before pregnancy (p = 0.01), pre-existing distant or locoregional metastases (p = 0.02) and delayed administration of radio-iodine therapy (p = 0.01). Interval between diagnosis and pregnancy, TSH level during pregnancy or the pre-conception thyroglobulin level did not have a statistically significant impact. Pregnancy was not associated with progression or recurrence of thyroid cancer (adjusted risk ratio 1.04, 95% confidence interval 0.91-1.32).

Conclusion

this study shows that pregnancy has no impact on recurrence or progression of thyroid cancer in patients declared in remission prior to conception.

Additional Tissue Sampling Trials Did Not Change Our Thyroid Practice

Simple Summary

Some studies have suggested that the use of additional tissue blocks to diagnose follicular thyroid carcinoma (FTC) could increase the accuracy of diagnosis and improve prognosis, and entire capsule sampling was recommended for a definitive diagnosis of borderline thyroid tumors in 2016. We conducted a study in 2016 to examine whether additional tissue sampling of the encapsulated follicular tumor increases the diagnosis of malignant cases in our patient cohort. Furthermore, the diagnosis was reclassified according to the 4th edition of the World Health Organization’s classification system. The additional tissue sampling only had a slight impact on our thyroid practice and resulted in no benefits to the patient; therefore, we decided to cease it.

Abstract

This study aimed to determine whether additional tissue sampling of encapsulated thyroid nodules would increase the frequency of follicular thyroid carcinoma (FTC) diagnoses. We examined thyroid tissue specimens from 86 patients suspected of FTC (84.9% female; mean age, 49.0 ± 17.8 years). The number of tissue blocks created for pathological assessments ranged from 3 to 20 (mean, 9.1 ± 4.1); the numbers in the previous method recommended by the Japanese General Rules for the Description of Thyroid Cancer and additional blocks ranged from 1 to 12 (mean, 6.0 ± 2.8) and from 1 to 8 (mean, 3.1 ± 2.0), respectively. The additional blocks were subsequently examined to determine whether any diagnoses changed from those based on the previous method. Five patients were diagnosed with FTC using the previous method; however, additional tissue blocks led to the diagnosis of FTC in 6 patients, as 1 diagnosis was revised from follicular adenoma to FTC. It has been reported that increasing the number of tissue blocks used for pathological assessments can increase the frequency of FTC diagnoses; however, this was not clinically significant in thyroid carcinoma, which requires completion thyroidectomy and radioactive iodine treatment. It resulted in no benefits to the patient because all minimally invasive FTCs, follicular tumors of uncertain malignant potential (FT-UMP), and follicular adenomas are treated with lobectomy alone in Japan. Additional tissue sampling only had a slight impact on our thyroid practice; therefore, we decided to cease it.

Artificial Intelligence for Personalized Medicine in Thyroid Cancer: Current Status and Future Perspectives

Thyroid cancers (TC) have increasingly been detected following advances in diagnostic methods. Risk stratification guided by refined information becomes a crucial step toward the goal of personalized medicine. The diagnosis of TC mainly relies on imaging analysis, but visual examination may not reveal much information and not enable comprehensive analysis. Artificial intelligence (AI) is a technology used to extract and quantify key image information by simulating complex human functions. This latent, precise information contributes to stratify TC on the distinct risk and drives tailored management to transit from the surface (population-based) to a point (individual-based). In this review, we started with several challenges regarding personalized care in TC, for example, inconsistent rating ability of ultrasound physicians, uncertainty in cytopathological diagnosis, difficulty in discriminating follicular neoplasms, and inaccurate prognostication. We then analyzed and summarized the advances of AI to extract and analyze morphological, textural, and molecular features to reveal the ground truth of TC. Consequently, their combination with AI technology will make individual medical strategies possible.

Complete diaphysis resorption of the femur: A case report in a metastatic papillary thyroid cancer

INTRODUCTION

Although differentiated thyroid cancers generally have a good prognosis, a small proportion of patients will have recurrent or progressive disease. Bone resorption due to thyroid cancer can cause significant challenges in the clinical management and rehabilitation.

PRESENTED CASE

Nearly total femur resorption was found as a first presentation in a patient with thyroid cancer. The patient complained about chronic pain in her left thigh that had progressed into an inability to walk. She was treated by a traditional healer for six years before she was persuaded by a social worker to seek medical help. X-rays showed pathological loss of the right diaphyseal femur. Neck CT-scan showed a left thyroid mass with tracheal deviation, with multiple lytic lesions in the sternum and 5th rib. Needle biopsy of the thyroid mass resulted in an inconclusive follicular neoplasm. Total thyroidectomy and neck dissection revealed a classical type of papillary thyroid carcinoma. After thyroid ablation, she opted for palliative radiotherapy and bisphosphonate treatment for the bone metastases.

DISCUSSION

Bone metastases are rarely detected at the time of thyroid cancer diagnosis. In the presence of bone metastasis, median survival of well-differentiated thyroid cancer decreases into only 4 years. Bone metastases are often neglected and less studied than regional lymph node and lung metastases.

CONCLUSION

Although well differentiated thyroid cancer is usually indolent, a neglected bone metastasis at an initial diagnosis might adversely affect patient's quality of life and prognosis.

An overview of thyroid fine-needle aspiration practice in Myanmar

Fine-needle aspiration cytology (FNAC) of the thyroid is a widely accepted method for aiding the diagnosis of thyroid nodules. In Myanmar, it has been done since the early 1990s, and mainly performed by surgeons and otorhinolaryngologists. The interpretation of cytology is solely made by pathologists. Although some of the experts particularly those from specialist hospitals use the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), many still prefer the British five-tier cytopathology report. Available local publications addressing the accuracy of FNAC and cytologic-histologic correlations were queried. Ten studies performed in 1991-2018 on 540 thyroid nodules were included. Cytologic-histologic correlations showed a range of sensitivity from 64.29% to 100%, specificity from 93% to 100%, and diagnostic accuracy from 94% to 100%. The adoption of TBSRTC by pathologists is still slow and should be encouraged via seminars and training programs. Further multihospital-based large cohort studies with uniform design and adequate follow-up are needed to better promote and assess utility of thyroid FNAC in Myanmar.

An affordable immunohistochemical approach to estimate the prevalence of BRAFV600E in large cohort studies-establishing the baseline rate of BRAF mutation in an institutional series of papillary thyroid carcinoma from Thailand

Background

Papillary thyroid carcinoma (PTC) accounts for the majority of diagnoses of thyroid carcinoma. BRAF^V600E mutation is the most common genetic alteration in PTC, which has diagnostic and prognostic significance. The rate of BRAF^V600E mutation in PTC from Thailand has not been reported. Our purpose was to estimate the prevalence of BRAF mutation in a large institutional series using an affordable approach, which combined mutation-specific immunohistochemistry (IHC) with VE1 antibody and tissue microarray (TMA).

Methods

A total of 476 PTC cases plotted on TMA were employed for determining the mutation status in this study. The cancer tissue of initial 100 cases (pilot study) were analyzed for BRAF^V600E mutation by using both direct sequencing and VE1 immunostaining. For the subsequent PTC cases, VE1 IHC was used as an alternative to direct sequencing for the detection of mutation. Univariate and multivariate analyses were done to determine the association of clinicopathological variables with BRAF^V600E mutation.

Results

In the pilot study, VE1 IHC showed excellent analytical performance (κ=0.884) for detecting BRAF^V600E mutation in PTC TMA as compared to direct sequencing. The prevalence of BRAF^V600E in the whole cohort was 60.9% by using VE1 IHC. The mutation was commonly seen in tall cell (92.9%) and classic (70.2%) variants of PTC. Multivariate analysis (P<0.05) showed association of BRAF^V600E with histological type of tumor, extrathyroidal extension, and absence of Hashimoto's thyroiditis.

Conclusions

In conclusion, BRAF^V600E mutation was detected in 60.9% of Thai PTC and it was associated with several aggressive clinicopathological variables of thyroid cancer. VE1 IHC proved as a reliable method able to replace direct sequencing for detection of the mutation. A combination of mutation-specific IHC and TMA allows conducting large cohort studies more labor-saving and cost-efficiently.

The effect of implementing pre-surgical ultrasound-guided fine-needle aspiration biopsy on thyroid surgery, a 6-year interrupted time series analysis in Qilu Hospital of Shandong University

Background

Thyroid fine-needle aspiration biopsy (FNAB) is not well developed in most of the large academic hospitals in China, including Qilu Hospital of Shandong University. Ultrasound-guided FNAB (UG-FNAB) was initiated as a pre-surgical diagnostic method in 2015 in Qilu Hospital, and the current study evaluates its impact on the number of thyroid surgeries and the ratio of malignancy (ROM) in surgically resected cases, comparing the post and pre-UG-FNAB periods.

Methods

Thyroid surgery and UG-FNAB data for the study period (Jan 2013 to Dec 2018) were collected from the hospital information system (HIS). A natural experimental approach using segmented linear regression was performed on the interrupted time-series (ITS) data to estimate the level-change of the number and the trend-change of ROM of surgically resected cases following the implementation of UG-FNAB diagnosis.

Results

The number of UG-FNAB cases in Qilu Hospital increased rapidly from 1,367 in 2015 to 3,402 in 2018, with an average annual increase of 678 cases. Comparing the pre-UG-FNAB and post-UG-FNAB periods, the overall ROM of thyroid resections increased from 58.7% to 73.2% (P<0.01). Due to the implementation of UG-FNAB, the regression line of surgical cases showed an inflection point in March 2015, and the slope of the regression line of post-intervention was lower than that of pre-intervention. For each additional month, the ROM in thyroid surgical cases increased by 0.389% (P<0.01). After excluding the influence of time, the ROM in surgically resected thyroid cases increased by 4.781% due to the application of the UG-FNAB examination (P<0.01).

Conclusions

This successful implementation of UG-FNAB further improved overall ROMs in surgically resected cases particularly as we acquired further experience with the procedure and reduced unnecessary diagnostic surgeries for patients with benign and borderline lesions.

Precursor and borderline lesions of the thyroid (indolent lesions of epithelial origin): from theory to practice

The precursor lesions of thyroid neoplasms can arise from either C cells or follicular cells. Although MTC has an established and recognized precursor lesion, the C-cell hyperplasia, the same does not occur for the follicular cell-derived tumors, which are much more frequent. One of the significant obstacles to recognizing follicular cell-derived precursor lesions (FCPL) is the lack of refinement of the morphological spectrum and biology of these putative premalignant lesions. What are the "gold standard" histological criteria in thyroid pathology to identify the progression of dysplasia to cancer? Diagnostical irreproducibility and misnomer in the terminology of some FCPLs have been lying behind the answer to this question. The last past decades' advances in molecular pathology allow us to transform the knowledge in thyroid pathology to cancer prevention and early detection, which will only be possible by improving our understanding of the nature of thyroid precursor and borderline lesions. This review, amassed with the augmented expertise of thyroid pathology documented in the literature, is an attempt at underlining the present understanding of precursor and borderline lesions of the thyroid, with a particular highlight on practice differences in Asian and Western geographies.

Genetic differences in follicular thyroid carcinoma between Asian and Western countries: a systematic review

Thyroid cancer is the most common endocrine malignancy, and follicular thyroid carcinoma (FTC) is the second most common thyroid cancer following papillary thyroid carcinoma (PTC). RAS mutation and PAX8/PPARγ rearrangement are the two representative genetic alterations in FTC, and there are studies from various countries on their regional frequencies. In this study, we systematically reviewed all available literature aiming to create a complete global map showing the frequencies of these common oncogenic drivers in FTC and to highlight the trends in Asian and Western countries. We performed a search in two electronic databases and identified 71 studies that fit our criteria from 1,329 studies found with our database search terms. There were 54 articles with 1,143 FTC patients and 39 articles with 764 FTC patients available for calculating the frequency of RAS mutation and PAX8/PPARγ rearrangement, respectively. NRAS mutation was the most frequent RAS mutation in all regions, followed by HRAS and KRAS mutation. The frequency of RAS mutation in Asian countries was higher than Western countries (34% vs. 27%, P=0.006) when the mutation detection method was not taken into account. In contrast, this difference in RAS mutation incidence between Asian and Western countries (28% vs. 25%, P=0.47) did not show up in our subgroup analysis incorporating only studies using direct sequencing method. The reported difference of RAS mutation frequency in the previous literature might not be due to the true prevalence of RAS mutation. They could be attributed to the difference in the detection method. As to PAX8/PPARγ rearrangement, Western countries overall had a much higher prevalence than Asian countries (23% vs. 4%, P<0.001), but some European countries had a low incidence, implying regional heterogeneity of PAX8/PPARγ rearrangement. A substantial lack of mutation data in FTC was found in several regions of the world such as Central Asia, Middle East, Africa, and Central and South America. Our results provide the most comprehensive global status of representative genetic alterations in FTC and highlight the similarities and differences between Asian and Western countries.

Utility of a multigene testing for preoperative evaluation of indeterminate thyroid nodules: A prospective blinded single center study in China

Background

Thyroid nodules are highly prevalent, with fine‐needle aspiration (FNA) commonly used as the standard preoperative tool for their diagnosis. However, the method classifies some of the samples as indeterminate, leading to unnecessary surgery. In this study, we evaluated the value of next‐generation sequencing (NGS) for cancer diagnosis in indeterminate thyroid nodules.

Materials and methods

We performed a prospective, blinded cohort study on 189 patients, with 196 Bethesda III/IV nodules. Specifically, we analyzed DNA mutations and RNA fusions across the FNA samples using NGS, then reviewed follow‐up reports from 84 nodules following definitive surgery, to determine the assay performance.

Results

Enough DNA and RNA were obtained in 188 nodules, revealing mutations or fusions in 34.6% of them. The most frequently mutated genes were RAS, followed by BRAF V600E. Based on surgical pathology, 39% (33/84) and 4.8% (4/84) of the nodules were malignant and intermediate, respectively. According to the risk stratification criteria, 28 cases were categorized High‐Risk group, all of the resected nodules (n = 20) were malignant. Twenty‐four thyroid nodules were in the Low‐Risk group, 28.6% (4/14) surgically removed nodules were malignant. In the Benign‐Like category, 18.0% (9/50) were malignant. Five out of 13 nodules with benign mutations were resected, including SPOP, EZH1, and ZNF148, all of them were benign. If genetic alterations annotated with High‐Risk or Low‐Risk was considered as positive, and negative if Benign‐Like. Multigene testing revealed sensitivity, specificity, positive predictive values (PPV), and negative predictive value (NPV) of 73%, 80%, 71%, and 82%, respectively. In addition, if four intermediate nodules were counted as malignant, the PPV and NPV were 71% and 74%.

Conclusion

Our results allow for further stratification of Bethesda III/IV thyroid nodules based on the risk of their malignancy. SPOP, EZH1, and ZNF148 mutations may be used as benign markers.

Clinical Implication of World Health Organization Classification in Patients with Follicular Thyroid Carcinoma in South Korea: A Multicenter Cohort Study

BACKGROUND

The study aimed to compare the prognostic value of the 4th edition of World Health Organization classification (WHO-2017) with the previous WHO classification (WHO-2004) for follicular thyroid carcinoma (FTC).

METHODS

This multicenter retrospective cohort study included 318 patients with FTC from five tertiary centers who underwent thyroid surgery between 1996 and 2009. We evaluated the prognosis of patients with minimally invasive (MI), encapsulated angioinvasive (EA), and widely invasive (WI) FTC according to WHO-2017. Further, we evaluated the proportion of variation explained (PVE) and Harrell's C-index to compare the predictability of disease-free survival (DFS) and disease-specific survival (DSS).

RESULTS

In total, 227, 58, and 33 patients had MI-, EA-, and WI-FTC, respectively. During a median follow-up of 10.6 years, 46 (14.5%) patients had disease recurrence and 20 (6.3%) patients died from FTC. The 10-year DFS rates of patients with MI-, EA-, and WI-FTC were 91.1%, 78.2%, and 54.9%, respectively (P&lt;0.001, PVE=7.1%, C-index=0.649). The corresponding 10-year DSS rates were 95.9%, 93.5%, and 73.5%, respectively (P&lt;0.001, PVE=2.6%, C-index=0.624). The PVE and C-index values were higher using WHO-2017 than using WHO-2004 for the prediction of DFS, but not for DSS. In multivariate analysis, older age (P=0.02), gross extrathyroidal extension (ETE) (P=0.003), and distant metastasis (P&lt;0.001) were independent risk factors for DSS.

CONCLUSION

WHO-2017 improves the predictability of DFS, but not DSS, in patients with FTC. Distant metastasis, gross ETE and older age (≥55 years) were independent risk factors for DSS.

Analysis of overall survival in differentiated thyroid cancer patients with double primary malignancy

Differentiated thyroid cancer (DTC) survivors are at increased risk of developing double primary malignancy (DPM). The aim of this study was to investigate clinicopathological characteristics and survival in DTC patients diagnosed with DPM. A total of 975 patients with DTC diagnosed between 2013 and 2017, treated, and followed at a medical center in Taiwan were retrospectively reviewed. Data from enrolled patients were analyzed for differences in prognosis dependent on the presence of DPM, and which clinicopathological variables affected their prognosis. Among 975 thyroid cancer patients, 94 (9.6%) were diagnosed with DPMs and 16 (1.6%) patients died of any cause. DPM patients had a greater proportion of males, had a higher mean age, more commonly presented with a thyroid mass incidentally by imaging and cervical lymph node metastases, showed a more advanced thyroid cancer stage, and had a higher proportion of lymph node metastases. Overall survival (OS) was significantly lower in patients diagnosed with DPM. Male gender (hazard ratio [HR] = 4.597), two or more DPMs (HR = 8.071), and shorter time interval between two cancers occurrences (HR = 7.101) were significantly risk factors for DPM-related death. In conclusion, the risk of developing DPM in DTC patients was elevated in older, male patients with an advanced tumor-node-metastasis stage. DPM adversely affected the OS of thyroid cancer patients. Male gender, two or more DPMs, and shorter time interval between occurrences were significant risk factors for OS in DPM patients.

Predictive factors of lateral lymph node metastasis in conventional papillary thyroid carcinoma

BACKGROUND

Lymph node metastasis (LNM) has been a significant predictor for local recurrence and distant metastasis in papillary thyroid carcinoma (PTC). However, the clinical predictors for conventional papillary thyroid carcinoma (CPTC) with lateral lymph node metastasis (LLNM) have yet to be established. Our work aimed to effectively identify the risk factors of LLNM in CPTC, helping surgeons to devise better individualized therapy strategies.

METHODS

We retrospectively analyzed 652 patients who were diagnosed with CPTC in the Department of General Surgery at Guangdong Provincial People's Hospital between October 2015 and June 2019. Univariate and multivariate logistic regression was used to analyze the correlation between clinicopathological characteristics and the LLNM of CPTC.

RESULTS

The incidence of LLNM in CPTC was 29.75% (194 of 652 patients). Univariate analysis found that LLNM was significantly associated with gender, age, number of central lymph nodes (CLNs), primary tumor location, multifocality, maximum tumor diameter, and BRAF V600E mutation. Independent risk factors for LLNM were multifocality (P=0.017, OR =4.325, 95% CI: 1.298-14.408), maximum tumor diameter (P<0.001, OR =4.076, 95% CI: 1.945-8.540), primary tumor location (P=0.037, OR =2.127, 95% CI: 1.046-4.328), number of CLNs (P<0.001, OR =8.604, 95% CI: 3.630-20.390), and BRAF V600E mutation (P=0.001, OR =3.913, 95% CI: 1.803-8.496) by multivariate analysis.

CONCLUSIONS

LLNM in CPTC was related to the large volume of central lymph node metastasis (CLNM), tumor located in the upper lobe, multifocality, tumor diameter >2 cm, and BRAF V600E mutation-negative, which should be considered when examining patients with suspected metastasis in the lateral compartment.

Complete response in anaplastic lymphoma kinase–rearranged oncocytic thyroid cancer: A case report and review of literature

BACKGROUND

Oncocytic carcinoma of the thyroid is a rare disease, characterized by a poor prognosis and low response rate to radioiodine therapy. Crizotinib is a specific anaplastic lymphoma kinase (ALK) inhibitor, which was initially developed in non-small cell lung cancer. Other solid tumors harboring a translocation in ALK have been described, such as renal carcinoma, thyroid, colorectal, ovarian cancers, and spitzoid melanoma. The research of ALK rearrangements in thyroid tumor is a promising therapeutic track, and treatments need to be explored.

CASE SUMMARY

We report the case of a 76-year-old woman with a history of multinodular goiter, who was hospitalized for impairment of her general condition. She was diagnosed with metastatic oncocytic thyroid cancer. Synchrone metastases were found: Multiple mediastinal lymphadenopathies, lytic bone lesions and bilateral mammary lumps. Fluorescence in situ hybridization analysis revealed an ALK rearrangement in 61% of cells. No other mutation was found. A tumor board discussion based on molecular characteristics of the tumor suggested initiating a daily treatment by crizotinib, a specific ALK inhibitor. A positron emission tomography scan performed 4 mo after the initiation of crizotinib showed a complete metabolic response.

CONCLUSION

This case highlights an unexpected efficacy of crizotinib in an ALK-rearranged thyroid tumor, and the need of further assessments.

Six1 Overexpression Promotes Glucose Metabolism and Invasion Through Regulation of GLUT3, MMP2 and Snail in Thyroid Cancer Cells

Introduction

Sineoculis homeobox homolog 1 (Six1) overexpression has been implicated in several human cancers. To date, its clinical significance and potential function in human thyroid cancer remain unclear.

Methods

Immunohistochemistry was used to examine the protein expression of BCAT1 in 89 cases of thyroid cancer tissues. We overexpressed and knockdown Six1 in TPC-1 and B-CPAP thyroid cancer cell lines. Biological roles and potential mechanisms of Six1 were examined using CCK-8, colony formation assay, Matrigel invasion assay, Western blot, PCR, ATP assay, and 2-NBDG uptake assay.

Results

We showed that Six1 protein was upregulated in thyroid cancers and was associated with tumor size and nodal metastasis. Analysis of TCGA dataset indicated that Six1 mRNA was higher in thyroid cancers compared with normal thyroid. CCK-8, colony formation and Matrigel invasion assays demonstrated that Six1 overexpression promoted proliferation, colony number and invasion while Six1 siRNA knockdown inhibited the growth rate, colony formation ability and invasive ability in both cell lines. Notably, Six1 upregulated glucose consumption, lactate production level and ATP level. 2-NBDG uptake analysis showed that Six1 overexpression upregulated glucose uptake while Six1 knockdown inhibited glucose uptake. Further analysis revealed that Six1 overexpression upregulated Snail, MMP2 and GLUT3 at both mRNA and protein levels. TCGA analysis demonstrated positive associations between Six1 and Snail, MMP2 and GLUT3 at the mRNA levels.

Conclusion

Taken together, our data demonstrated that Six1 was upregulated in human thyroid cancers and promoted cell proliferation and invasion. Our data also revealed new roles of Six1 in thyroid cancer development by modulating glucose metabolism and invasion, possibly through regulation of Snail, MMP2 and GLUT3.

Histopathologic Assessment of Capsular Invasion in Follicular Thyroid Neoplasms-an Observer Variation Study

The assessment of capsular invasion is an essential but challenging step in the diagnosis of encapsulated follicular thyroid neoplasms. Therefore, interobserver agreement in the assessment of capsular invasion in these tumors was investigated among 11 thyroid pathologists by using virtual slides of 20 cases in which the original diagnosis considered the differential diagnosis of definite capsular invasion versus questionable capsular invasion. The assessment of capsular invasion was divided into three categories: (1) non-invasive, (2) questionable invasive, and (3) clear-cut invasive. The interobserver agreements for clear-cut invasive and non-invasive categories were fair (Kappa value = 0.578 and 0.404, respectively), whereas agreement for the questionable invasion was poor (Kappa value = 0.186). Disagreements in the assessment of invasion resulted in variable final pathological diagnoses. For example, the agreement for a diagnosis of malignancy was only fair (Kappa value = 0.545). Moreover, pathologists did not have a uniform approach for rendering a final diagnosis in cases with questionable capsular invasion, though nine of 11 pathologists did use the follicular tumor of uncertain malignant potential diagnosis as proposed by the World Health Organization classification of endocrine organs published in 2017. In conclusion, this study revealed considerable interobserver variation in the evaluation of capsular invasion, especially in follicular neoplasms with questionable invasion.

Prognostic Implications of CD10 and CD15 Expression in Papillary Thyroid Carcinoma

Patients with papillary thyroid carcinoma (PTC) have excellent survival, but recurrence remains a major problem in the management of PTC. We aimed to determine the prognostic impact of the expression of CD10 and CD15 in patients with PTC. Immunohistochemistry for CD10 and CD15 was performed on the tissue microarrays of 515 patients with PTC. The expression of CD10 and CD15 was detected in 201 (39.0%) and 295 (57.3%) of 515 PTC cases, respectively, but not in the adjacent benign thyroid tissue. Recurrence was inversely correlated with CD15 expression (p = 0.034) but not with CD10 expression. In 467 PTC patients treated with radioiodine remnant ablation, the CD15 expression had an adjusted hazard ratio of 0.500 (p = 0.024) for recurrence-free survival and an adjusted odds ratio of 2.678 (p = 0.015) for predicting long-term excellent therapeutic response. CD10 expression was not associated with clinical outcomes. In the Cancer Genome Atlas dataset, the expression level of FUT4 (CD15) mRNA was higher in the low/intermediate-risk group for recurrence than in the high-risk group and exhibited positive correlation with SLC5A5 (NIS) mRNA expression (p = 0.003). Taken together, CD15 expression was identified as an independent prognostic marker for improved prognosis in PTC patients.

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.