Special types of thyroid carcinoma

External validation of a deep learning-based algorithm for detection of tall cells in papillary thyroid carcinoma: A multicenter study

The tall cell subtype (TC-PTC) is an aggressive subtype of papillary thyroid carcinoma (PTC). The TC-PTC is defined as a PTC comprising at least 30% epithelial cells that are three times as tall as they are wide. In practice, this definition is difficult to adhere to, resulting in high inter-observer variability. In this multicenter study, we validated a previously trained deep learning (DL)-based algorithm for detection of tall cells on 160 externally collected hematoxylin and eosin (HE)-stained PTC whole-slide images. In a test set of 360 manual annotations of regions of interest from 18 separate tissue sections in the external dataset, the DL-based algorithm detected TCs with a sensitivity of 90.6% and a specificity of 88.5%. The DL algorithm detected non-TC areas with a sensitivity of 81.6% and a specificity of 92.9%. In the validation datasets, 20% and 30% TC thresholds correlated with a significantly shorter relapse-free survival. In conclusion, the DL algorithm detected TCs in unseen, external scanned HE tissue slides with high sensitivity and specificity without any retraining.

Predicting tall-cell subtype of papillary thyroid carcinomas independently with preoperative multimodal ultrasound

OBJECTIVES

This study aimed to explore the differences between tall-cell subtype of papillary thyroid carcinoma (TCPTC) and classical papillary thyroid carcinoma (cPTC) using multimodal ultrasound, and identify independent risk factors for TCPTC to compensate the deficiency of preoperative cytological and molecular diagnosis on PTC subtypes.

METHODS

Forty-six TCPTC patients and 92 cPTC patients were included. Each patient received grey-scale ultrasound, colour Dopplor flow imaging (CDFI) and shear-wave elastography (SWE) preoperatively. Clinicopathologic information, grey-scale ultrasound features, CDFI features and SWE features of 98 lesions were compared using univariate analysis to find out predictors of TCPTC, based on which, a predictive model was built to differentiate TCPTC from cPTC and validated with 40 patients.

RESULTS

Univariate and multivariate analyses identified that extra-thyroidal extension (odds ratio [OR], 15.12; 95% CI, 2.26-115.44), aspect ratio (≥0.91) (OR, 29.34; 95% CI, 1.29-26.23), and maximum diameter ≥14.6 mm (OR, 20.79; 95% CI, 3.87-111.47) were the independent risk factors for TCPTC. Logistic regression equation: P = 1/1+ExpΣ[-5.099 + 3.004 × (if size ≥14.6 mm) + 2.957 × (if aspect ratio ≥ 0.91) + 2.819 × (if extra-thyroidal extension). The prediction model had a good discrimination performance for TCPTC: the area under the receiver-operator-characteristic curve, sensitivity, and specificity were 0.928, 0.848, and 0.954 in cohort 1, and the corresponding values in cohort 2 were 0.943, 0.923, and 0.926, respectively.

CONCLUSION

Ultrasound has the potential for differential diagnosis of TCPTC from cPTC. A prediction model based on ultrasound characteristics (extra-thyroidal extension, aspect ratio ≥0.91, and maximum diameter ≥14.6 mm) was useful in predicting TCPTC.

ADVANCES IN KNOWLEDGE

Multimodal ultrasound prediction of TCPTC was a supplement to preoperative cytological diagnosis and molecular diagnosis of PTC subtypes.

Identification of disulfidptosis-associated genes and characterization of immune cell infiltration in thyroid carcinoma

OBJECTIVE

The primary objective of this study is to conduct a comprehensive screening and analysis of differentially expressed genes related to disulfidoptosis (DEDRGs) in thyroid carcinoma (THCA). This entails delving into the intricate characterization of immune cell infiltration within the THCA context and subsequently formulating and validating a novel prognostic model.

METHOD

To achieve our objectives, we first delineated two distinct subtypes of disulfidoptosis-related genes (DRGs) via consensus clustering methodology. Subsequently, employing the limma R package, we identified the DEDRGs critical for our investigation. These DEDRGs underwent meticulous validation across various databases, alongside an in-depth analysis of gene regulation. Employing functional enrichment techniques, we explored the potential molecular mechanisms underlying disulfidoptosis in THCA. Furthermore, we scrutinized the immune landscape within the two identified subtypes utilizing CIBERSORT and ESTIMATE algorithms. The construction of the prognostic model for THCA entailed intricate methodologies including univariate, multivariate Cox regression, and LASSO regression algorithms. The validity and efficacy of our prognostic model were corroborated through Kaplan-Meier survival curves and ROC curves. Additionally, a nomogram was meticulously formulated to facilitate the prediction of patient prognosis. To fortify our findings, we conducted a comprehensive Bayesian co-localization analysis coupled with rigorous in vitro experimentation, aimed at unequivocally establishing the validity of the identified DEDRGs.

RESULT

Our analyses unveiled Cluster C1, characterized by elevated expression levels of DEDRGs, as harboring a favorable prognosis accompanied by abundant immune cell infiltration. Correlation analyses underscored predominantly positive associations among the DEDRGs, further affirming their significance in THCA. Differential expression patterns of DEDRGs between tumor samples and normal tissues were evident across the GEPIA and HPA databases. Insights from the TIMER database underscored a robust correlation between DEDRGs and immune cell infiltration. KEGG analysis elucidated the enrichment of DEDRGs primarily in pivotal pathways including MAPK, PPAR signaling pathway, and Proteoglycans in cancer. Furthermore, analyses using CIBERSORT and ESTIMATE algorithms shed light on the crucial role played by DEDRGs in shaping the immune microenvironment. The prognostic model, anchored by five genes intricately associated with THCA prognosis, exhibited commendable predictive accuracy and was intricately linked to the tumor immune microenvironment. Notably, patients categorized with low-risk scores stood to potentially benefit more from immunotherapy. The validation of DEDRGs unequivocally underscores the protective role of INF2 in THCA.

CONCLUSION

In summary, our study delineates two discernible subtypes intricately associated with DRGs, revealing profound disparities in immune infiltration and survival prognosis within the THCA milieu. The implications of our findings extend to potential treatment strategies for THCA patients, which could entail targeted interventions directed towards DEDRGs and prognostic genes, thereby influencing disulfidptosis and the immune microenvironment. Moreover, the robust predictive capability demonstrated by our prognostic model, based on the five genes (ANGPTL7, FIRRE, ODAPH, PROKR1, SFRP5), underscores its potential clinical utility in guiding personalized therapeutic approaches for THCA patients.

Prevalence of Differentiated High-Grade Thyroid Carcinoma Among Well-Differentiated Tumors: A Systematic Review and Meta-Analysis

Background: The current edition of the World Health Organization (WHO) classification of endocrine tumors introduced grading for follicular cell-derived thyroid cancer. Tumors with necrosis and/or high mitotic count but not fulfilling the Turin criteria for poorly differentiated carcinoma will be reclassified as differentiated high-grade thyroid carcinoma (DHGTC). However, the impact of this reclassification has not been evaluated. In this study, we performed a systematic review and meta-analysis to estimate the prevalence of this new entry across thyroid tumor subtypes. Methods: In this systematic review and meta-analysis, studies reporting data on necrosis and/or mitoses in well-differentiated thyroid carcinoma (WDTC) were used to estimate the prevalence of DHGTC. Heterogeneity and potential publication bias were also evaluated. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed, and quality assessment was performed using a modification of the Newcastle-Ottawa scale. The study has been registered in the International Prospective Register of Systematic Reviews (PROSPERO, ID: CRD42022378716). Results: In clinically unselected patients, the prevalence of DHGTC in WDTC was 0.072 [95% confidence interval, CI, = 0.045-0.113]. The proportion of high-grade tumors greatly varied across growth patterns and subtypes. Overall, the prevalence of DHGTC was higher in follicular thyroid carcinoma (FTC; 0.146 [CI = 0.101-0.205]) than in papillary thyroid carcinoma (PTC; 0.059 [CI = 0.036-0.097]). Diffuse sclerosing, follicular, and classic subtype PTC had the lowest rates of high-grade features (i.e., 0.018 [CI = 0.004-0.084]; 0.036 [CI = 0.010-0.124]; and 0.042 [CI = 0.027-0.066], respectively), while a greater proportion of solid trabecular and histologically aggressive PTC could be reclassified as DHGTC (i.e., 0.154 [CI = 0.067-0.314] and 0.168 [CI = 0.108-0.252], respectively). Similar proportions were obtained for minimally and widely invasive FTC (i.e., 0.136 [CI = 0.058-0.287] and 0.152 [CI = 0.086-0.254], respectively). Finally, in a cohort of patients with poor prognosis (i.e., fatal cases, metastatic and radioiodine resistant tumors, cases with biochemical recurrence), the proportion of DHGTC was 0.287 [CI = 0.155-0.469]. Conclusions: Following the current WHO indications, some tumors will be reclassified as DHGTC. The proportion of tumors with high-grade features is relevant in FTC, solid trabecular, and histologically aggressive PTC subtypes. A remarkable enrichment in DHGTC among patients with poor prognosis confirms the negative impact of high-grade features on outcome.

Papillary Thyroid Carcinoma With Lymphoepithelial Features and Lacking Association With Epstein-Barr Virus (EBV): A Rare Case

Papillary thyroid carcinoma (PTC) is the most common primary thyroid malignancy. PTC is diagnosed based on its hallmark nuclear characteristics, but a myriad of histological variants has been identified some of which can be diagnostically challenging due to its rarity and overlapping histomorphology with other entities. We report a rare variant of PTC with lymphoepithelial features which lacked association with Epstein-Barr Virus (EBV). In such cases, a thorough workup to rule out metastasis from other sites should be undertaken.

Cytological and Ultrasound Features of Thyroid Nodules Correlate With Histotypes and Variants of Thyroid Carcinoma

CONTEXT

Prognosis is excellent for papillary thyroid carcinoma (PTC), noninvasive follicular thyroid neoplasia with papillary-like nuclear features (NIFT-P), and follicular thyroid carcinoma (FTC) but is poor for poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC). Among PTCs, the prognosis is more favorable for follicular (FV-PTC) and classic (CV-PTC) than for tall cell (TCV-PTC), and solid (SV-PTC) variants.

OBJECTIVE

To associate histotypes and variants of thyroid carcinoma with ultrasound and cytological features.

METHODS

Histology of 1018 benign tumors and 514 PTC (249 CV, 167 FV, 49 TC, 34 SV, and 15 other variants), 52 NIFT-P, 50 FTC, 11 PDTC, and 3 ATC was correlated with fine-needle aspiration biopsy categories (Italian classification: TIR1, TIR2, TIR3A, TIR3B, TIR4, and TIR5) and ultrasound features at the Endocrinology Unit, University Hospital of Pisa. In total, 1117 patients with thyroid nodule(s) who underwent thyroidectomy were included.

RESULTS

Of PTC, 36.3% had indeterminate cytology (TIR3A or TIR3B), 56.6% were suspicious for malignancy or malignant (TIR4 or TIR5); 84.0% FTC and 69.3% NIFT-P were TIR3A or TIR3B; 72.5% FV-PTC and 73.6% SV-PTC were TIR3A or TIR3B; 79.9% CV-PTC and 95.9% TCV-PTC were TIR4 or TIR5. The association of a hypoechoic pattern, irregular margins, and no microcalcifications was more frequent in TCV-PTC than in CV-PTC (P = .02, positive predictive value = 38.9%; negative predictive value = 85.5%).

CONCLUSION

At cytology, most FTC, NIFT-P, FV-PTC, and SV-PTC were indeterminate, most CV-PTC and TCV-PTC were suspicious for malignancy or malignant. Ultrasound can be helpful in ruling out TCV-PTC.

MicroRNA-130a-3p impedes the progression of papillary thyroid carcinoma through downregulation of KPNB1 by targeting PSME3

BACKGROUND

Papillary thyroid carcinoma (PTC) is the main type of thyroid cancer (THCA). Despite the good prognosis, some PTC patients may deteriorate into more aggressive disease, leading to poor survival. Our study aimed to explore the role of microRNA (miR)-130a-3p in regulating PTC.

METHODS

After transfection with miR-130a-3p-mimic, OE-PSME3, or miR-130a-3p-mimic + OE-KPNB1 in PTC cells (TPC-1), CCK-8, Transwell, scratch, and flow cytometry experiments were performed to analyze TPC-1 cell proliferation, invasion, migration, and apoptosis. Western blotting was used to detect proliferation or invasion-related protein markers (PCNA, E-cadherin, and N-cadherin). The RNA22 database, dual-luciferase reporter assay, and RNA pull-down assay were applied for the prediction and verification of the binding site between miR-130a-3p and PSME3. Pan-cancer software identified a positive correlation between PSME3 and KPNB1 in THCA. Co-immunoprecipitation was utilized to verify the interaction of PSME3 with KPNB1. Nude mice were transplanted with TPC-1 cells overexpressing miR-130a-3p. The tumors were isolated for detection of the expression of miR-130a-3p, PSME3, KPNB1, Ki-67, and CD31.

RESULTS

miR-130a-3p was lowly expressed in PTC cell lines. Upregulation of miR-130a-3p repressed the expression of PSME3 and KPNB1 and reduced the malignancy of TPC-1 cells in vitro, shown by inhibited cell proliferation, invasion, migration, and the expression of PCNA and N-cadherin. Also, overexpressed miR-130a-3p inhibited the growth of xenograft tumors in nude mice. miR-130a-3p bound to PSME3 which interacted with KPNB1.

CONCLUSION

miR-130a-3p impedes the progression of PTC by downregulating PSME3/KPNB1.

A case of lung carcinoma with a unique biphasic feature: Implications for histogenesis of "fake mucoepidermoid carcinoma" developing in the peripheral lung

We present a case of lung carcinoma with a unique biphasic feature. The patient was a 67-year-old male smoker with idiopathic pulmonary fibrosis (IPF). A subpleural tumor in the left lower lobe, embedded in fibrotic tissue, was resected. Histologically, the tumor consisted of major and minor components of mucoepidermoid carcinoma (MEC) and surrounding conventional lepidic adenocarcinoma, respectively. Both components had the same TP53 somatic mutation (p.V157F) but not Mastermind-like 2 (MAML2) gene rearrangement. The two components may have developed from an identical origin. The tumor could be trans-differentiating from lepidic adenocarcinoma to MEC, possibly promoted by IPF-induced tissue damage. The final diagnosis was "adenosquamous carcinoma with mucoepidermoid-like features (that may originate from lepidic adenocarcinoma)." This case has implications for the potential histogenesis of peripheral lung MEC. Over time, the MEC would expand and outgrow the lepidic adenocarcinoma, making it impossible to distinguish between fake and true MEC. The present case suggests that peripheral MEC could differ from proximal MEC in its histogenesis and molecular genetics. Thus, careful examination is necessary to diagnose peripheral lung MEC, particularly in patients with interstitial lung diseases.

Diffuse Sclerosing Papillary Thyroid Carcinoma: Clinicopathological Characteristics and Prognostic Implications Compared with Classic and Tall Cell Papillary Thyroid Cancer

BACKGROUND

The clinical behaviour and oncologic outcome of diffuse sclerosing papillary thyroid carcinoma (DS-PTC) is poorly understood. The objectives of this study were to compare the clinicopathological characteristics and oncological outcomes of DS-PTC to classic PTC (cPTC) and tall cell PTC (TC-PTC).

METHODS

After institutional review board approval, 86 DS-PTC, 2,080 cPTC, and 701 TC-PTC patients treated at MSKCC between 1986 and 2021 were identified. Clinicopathological characteristics were compared by using chi-square test. Kaplan-Meier and log rank were used to compare recurrence-free survival (RFS), disease-specific survival (DSS), and overall survival (OS). DS-PTC patients were propensity matched to cPTC and TC-PTC patients for further comparison.

RESULTS

DS-PTC patients were younger with more advanced disease than cPTC and TC-PTC (p < 0.05). Lymphovascular invasion (LVI), extranodal extension, and positive margins were more common in DS-PTC (p < 0.02). Propensity matching confirmed more aggressive histopathological features in DS-PTC. The median number of metastatic lymph nodes was significantly greater and DS-PTC metastases were RAI avid. DS-PTC 5-year RFS was 50.4% compared with 92.4% in cPTC and 88.4% in TC-PTC (p < 0.001). Multivariate analysis confirmed DS-PTC as an independent prognostic factor of recurrence. Ten-year DSS for DS-PTC was 100% compared with 97.1% in cPTC and 91.1% in TC-PTC. Differentiated high-grade, thyroid carcinoma DS had more advanced T-stage and worse 5-year RFS than DS-PTC.

CONCLUSIONS

DS-PTC presents with more advanced clinicopathological features than cPTC and TC-PTC. Large-volume nodal metastases and LVI are characteristic features. Almost half of patients develop recurrence despite aggressive initial management. Despite this, with successful salvage surgery DSS is excellent.

Clinico-pathological initial outcome of a newly adopted novel surgical technique for nodal metastatic thyroid cancer at a large-volume centre in a high-income developing country

Introduction

Thyroid cancer is the most common tumour in the endocrine system. In the past decade, the incidence of lymph node metastasis has increased, and so has the patient demand for a smaller scar. This research reports the surgical and patho-oncological short-term outcomes of a novel, minimally invasive neck dissection approach for thyroid carcinoma with lymph node metastases at the UAE's leading endocrine surgery centre.

Methods

This study employed a prospectively maintained surgical database to retrospectively analyse relevant parameters such as surgical complications, including bleeding, hypocalcaemia nerve injury and lymphatic fistula, as well as oncological metrics such as the type of tumour and the ratio of lymph node metastasis to the number of harvested lymph nodes in 100 patients that underwent open minimally invasive selective neck dissection.

Results

The study comprised 50 patients with thyroidectomy, with bilateral central compartment neck dissection (BCCND; 50%); 34 with thyroidectomy, BCCND and selective bilateral lateral compartment neck dissection (BLCND; 34%); and 16 patients with selective unilateral central and lateral compartment neck dissection by recurrent nodal disease (ULCND; 16%). The female-to-male gender ratio was 78:22, with median ages of 36 and 42 years, respectively. Histopathology findings revealed that 92% of patients had papillary thyroid cancer (PTC) and 8% had medullary thyroid cancer. The mean total number of lymph nodes removed was 22 in the BLCND group, 17 in the ULCND group and 8 in the BCCND group (p = 0.001). Furthermore, the average lymph node metastasis was significantly higher in the BLCND group (p = 0.002). The percentage of temporary hypoparathyroidism was 29.8% and it persisted for 1.3%. The lateral compartment dissection morbidity was as follows: Four male patients with tall cell infiltrative PTC presented with pre-existing vocal cord paresis, necessitating nerve resection and anastomosis, and two more developed it after surgery (1.1% of the nerve at risk). Lymphatic fistulas occurred in four patients (4%) who were treated conservatively. Two patients were readmitted due to symptomatic neck collection. Horner syndrome was discovered in just one female patient. Male gender, aggressive histology and lateral compartment dissection independently increased surgical morbidity. In a high-volume endocrine centre, the adoption of minimally invasive selective neck dissections to treat nodal metastatic thyroid cancer did not increase specific cervical surgery complications.

Role of ADAM33 short isoform as a tumor suppressor in the pathogenesis of thyroid cancer via oncogenic function disruption of full-length ADAM33

Thyroid cancer is the most prevalent endocrine malignancy globally; however, its underlying pathogenesis remains unclarified. Reportedly, alternative splicing is involved in processes such as embryonic stem and precursor cell differentiation, cell lineage reprogramming, and epithelial-mesenchymal transitions. ADAM33-n, an alternative splicing isoform of ADAM33, encodes a small protein containing 138 amino acids of the N-terminal of full-length ADAM33, which constructs a chaperone-like domain that was previously reported to bind and block the proteolysis activity of ADAM33. In this study, we reported for the first time that ADAM33-n was downregulated in thyroid cancer. The results of cell counting kit-8 and colony formation assays showed that ectopic ADAM33-n in papillary thyroid cancer cell lines restricted cell proliferation and colony formation. Moreover, we demonstrated that ectopic ADAM33-n reversed the oncogenic function of full-length ADAM33 in cell growth and colony formation in the MDA-T32 and BCPAP cells. These findings indicate the tumor suppressor ability of ADAM33-n. Altogether, our study findings present a potential explanatory model of how the downregulation of the oncogenic gene ADAM33 promotes the pathogenesis of thyroid cancer.

Identification and validation of eight estrogen-related genes for predicting prognosis of papillary thyroid cancer

Papillary thyroid cancer (PTC) is one of the most common malignant tumors in female, and estrogen can affect its progression. However, the targets and mechanisms of estrogen action in PTC remain unclear. Therefore, this study focuses on the relationship between estrogen-related genes (ERGs) expression and prognosis in PTC, particularly neuropeptide U (NMU), and its important role in tumor progression. Based on The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, differentially expressed genes (DEGs) predominantly enriched in ERGs were identified between PTC and normal tissue. Then, we identified ERGs that contributed most to PTC prognosis, including Transducer of ERBB2 1 (TOB1), trefoil factor 1 (TFF1), phospholipase A and acyltransferase 3 (PLAAT3), NMU, kinesin family member 20A (KIF20A), DNA topoisomerase II alpha (TOP2A), tetraspanin 13 (TSPAN13), and carboxypeptidase E (CPE). In addition, we confirmed that NMU was highly expressed in PTC and explored the effect of NMU on PTC cells proliferation in vitro and in vivo. The results showed that the proliferative capacity of PTC cells was significantly reduced with NMU knockdown. Moreover, the phosphorylation levels of the Kirsten rat sarcoma virus (KRAS) signaling pathway were significantly lower with NMU knockdown. These results suggest that ERGs, especially NMU, may be novel prognostic indicators in PTC.

Top 10 Nested Pattern Head and Neck Lesions to Notice

BACKGROUND

Nested is defined as "cellular clusters arranged in small groupings with intervening vascular or stromal networks, lacking lumens or glandular formation." Using this definition, multiple neoplastic and non-neoplastic lesions of the head and neck come into the differential. We have broadly organized the differential diagnosis of "nested" tumors into entities with neuroendocrine differentiation, squamous differentiation, thyroid follicular cell differentiation, and other lesions.

METHODS

Review.

RESULTS

Many different entities have a nested appearance and the morphologic, immunohistochemical, clinical, and radiographic features contribute to the differential diagnosis. The different tumors covered in this review include neuroendocrine neoplasms, paraganglioma, middle ear neuroendocrine tumor (formerly known as middle ear adenoma), medullary thyroid carcinoma, poorly differentiated thyroid carcinoma, olfactory neuroblastoma, ectopic pituitary neuroendocrine tumor, hyalinizing trabecular tumor, solid subtype of papillary thyroid carcinoma, solid cell nests/C-cell hyperplasia, necrotizing sialometaplasia, and meningioma.

CONCLUSION

In this review, we discuss the morphologic and immunohistochemical features of the covered entities as a guide to differential diagnosis when nested-patterned head and neck lesions are encountered.

The Impact of the 2022 WHO Classification of Thyroid Neoplasms on Everyday Practice of Cytopathology

This review outlines how the alterations in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors of the thyroid gland are likely to impact thyroid cytopathology. It is important to note that WHO subclassifies thyroid tumors into several new categories based on increased comprehension of the cell of origin, pathologic features (including cytopathology), molecular classification, and biological behavior. The 3rd edition of the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) will debut in the near future and will include changes in diagnostic category designations. The changes in the 5th edition of the WHO will in some instances subtly, and in other instances significantly, impact the cytological diagnoses. Moreover, these changes will also affect other thyroid FNA classification schemes used internationally for classifying thyroid FNA specimens.

No Longer Well-Differentiated: Diagnostic Criteria and Clinical Importance of Poorly Differentiated/High-Grade Thyroid Carcinoma

Poorly differentiated thyroid carcinoma (PDTC) and differentiated high-grade thyroid carcinoma (DHGTC) are uncommon thyroid malignancies, recently (re)codified into distinct entities with overlapping clinical significance. Recognizing them may be challenging for the general practitioner and subspecialty pathologist alike. This article will describe the required features to diagnose PDTC and DHGTC, differential diagnostic considerations, molecular findings, and clinical implications. It is intended to be a general synopsis of the most critical elements of PDTC and DHGTC as well as a summary of points in approaching these challenging cases.

High-Grade Non-Anaplastic Thyroid Carcinomas of Follicular Cell Origin: A Review of Poorly Differentiated and High-Grade Differentiated Carcinomas

Poorly differentiated thyroid carcinoma (PDTC) and high-grade differentiated thyroid carcinoma (HGDTC) are considered high-grade follicular-derived thyroid carcinomas, with prognoses intermediate between well-differentiated and anaplastic thyroid carcinoma. Both share the presence of invasion, thyroid follicular-cell origin, and tumor necrosis or increased mitoses (≥ 3 mitoses per 2 mm² in PDTC and ≥ 5 mitoses per 2 mm² in HGDTC), without anaplastic dedifferentiation. PDTC must possess solid, trabecular, or insular growth and lack classic papillary-like nuclei; HGDTC can be of any architectural or nuclear morphology (follicular-like, papillary-like, oncocytic). Transformation may be accompanied by acquisition of high-risk mutations (such as TP53 or TERT promoter) on top of RAS-like or BRAF p.V600E-like (including NTRK-fusion) initial driver mutations. These carcinomas most frequently affect adults and often present with metastases (20-50%) or wide local invasion. As PDTC and HGDTC may be radioactive iodine resistant, post-surgical therapy may consist of external beam radiotherapy or targeted, mutation-dependent chemotherapy, such as tyrosine kinase inhibitors. Ten-year disease specific survival is as low as 50%. Awareness of high-grade features in the diagnostic setting is important for patient prognosis and triage of tissue for molecular analysis in order to guide relevant clinical management and therapy.

Advances in Thyroid Pathology: High Grade Follicular Cell-derived Thyroid Carcinoma and Anaplastic Thyroid Carcinoma

In the upcoming World Health Organization fifth edition classification of endocrine tumors, there were several major changes related to high grade follicular-derived thyroid carcinoma (HGFCTC) and anaplastic thyroid carcinoma (ATC) based on emerging evidence about the diagnostic criteria clinical behavior, prognostic factors, and molecular signatures of these tumors. In this review, we aim to summarize the major evolutions of HGFCTC and ATC. HGFCTC is a nonanaplastic carcinoma with high grade features (High mitotic count, tumor necrosis). It is subdivided into poorly differentiated thyroid carcinoma diagnosed using the Turin proposal and differentiated high grade thyroid carcinoma. The latter is defined by the presence of the cytoarchitectutal features of well-differentiated thyroid carcinoma (eg, papillae) but harbors elevated mitotic activity and/or tumor necrosis. Poorly differentiated thyroid carcinoma is predominantly RAS -driven and associated with RAI avidity and high propensity for distant metastasis, whereas differentiated high grade thyroid carcinoma is mostly BRAFV600E -driven. ATC may show a wide range of histologic features. Carcinoma of pure squamous phenotype is associated with a high frequency of BRAF V600E mutations and is now considered as a subtype of ATC. There is a stepwise molecular progression from well-differentiated carcinoma to HGFCTC to ATC manifested by 1) early and persistent driver alteration in the MAPK pathway, particularly BRAF V600E and RAS mutations, and 2) gain of secondary aggressive molecular signatures (such as TERT promoter and TP53 mutations) when tumors progress from well-differentiated to high grade to anaplastic carcinoma.

Association of Programmed Death-Ligand 1 Expression with Aggressive Histological Types of Thyroid Carcinoma

Introduction

Immunohistochemical expression of programmed death-ligand 1 (PD-L1) has become a biomarker to predict the usefulness of cancer immunotherapy using PD-1/PD-L1 blockade in a variety of advanced-stage tumours. This emerging biomarker may serve to generate novel therapies for aggressive thyroid carcinoma (TC), which has not shown optimal results with existing treatments.

Methods

The present study investigated the relevance of PD-L1 expression in aggressive histological types of TC compared with that found in less aggressive types. Surgically resected specimens were investigated, including 52 cases of TC consisting of 26 cases of aggressive histological types and 26 cases of less aggressive histological types. Immunohistochemical examinations were carried out on paraffin blocks of both groups using a mouse monoclonal primary antibody against PD-L1 (clone 22C3). PD-L1 expression was evaluated by calculating the tumour proportion score (TPS) in both groups.

Results

The results revealed a significant difference in the median TPS value of PD-L1 expression between the two groups. The TPS values were found to be higher in the group of aggressive histological types of TC compared with those in the group of less aggressive histological types. A significant difference in TPS value was also found for the extrathyroidal extension variable.

Discussion

In conclusion, the present study found a significant association between PD-L1 expression and the aggressive histological type of TC. In addition, a potential association between PD-L1 expression and the presence of extrathyroidal extension of TC was observed. These findings provide novel approaches for immunotherapy as a potential new treatment modality in patients with aggressive histological types of TC.

Clinicopathologic and Prognostic Features of Pediatric Follicular Cell-derived Thyroid Carcinomas: A Retrospective Study of 222 Patients

Pediatric thyroid carcinomas (TCs) are rare and mainly approached based on data extrapolated from adults. We retrospectively reviewed 222 pediatric TCs (patient age less than or equal to 21 y). Lymph node (LN) disease volume at presentation was considered high if the largest positive LN measured ≥1 cm and/or >5 LNs were positive. High-grade follicular cell-derived thyroid carcinoma (HGFCTC) were defined by the presence of marked mitotic count and/or tumor necrosis and considered as high-risk histology along with papillary thyroid carcinomas (PTC) diffuse sclerosing variant (DSV). Disease-free survival (DFS) was analyzed. LN involvement at presentation was significantly associated with male sex, larger tumor size, lymphatic invasion, positive surgical margins, and distant metastases at presentation. Five- and 10-year DFS was 84% and 77%, respectively. Only 1 patient with HGFCTC died of disease. Within PTC variants, PTC-DSV was associated with adverse histopathologic parameters and higher regional disease spread, unlike PTC tall cell variant which did not portend worse behavior. The presence of necrosis conferred worse DFS ( P =0.006), while increased mitotic activity did not. While the entire HGFCTC group did not correlate with outcome ( P =0.071), HGFCTC with necrosis imparted worse DFS ( P =0.006). When restricted to PTC-DSV and HGFCTC with necrosis, high-risk histologic classification emerged as an independent prognostic parameter of DFS ( P =0.020). The excellent prognosis of pediatric TCs differs from that of adult TCs showing similar histologic features. While neither increased mitotic activity nor PTC tall cell variant histology predict adverse outcome, PTC-DSV and tumors with necrosis constitute high-risk histologic variants with an increased risk of protracted disease.

2022 European Thyroid Association Guidelines for the management of pediatric thyroid nodules and differentiated thyroid carcinoma

At present, no European recommendations for the management of pediatric thyroid nodules and differentiated thyroid carcinoma (DTC) exist. Differences in clinical, molecular, and pathological characteristics between pediatric and adult DTC emphasize the need for specific recommendations for the pediatric population. An expert panel was instituted by the executive committee of the European Thyroid Association including an international community of experts from a variety of disciplines including pediatric and adult endocrinology, pathology, endocrine surgery, nuclear medicine, clinical genetics, and oncology. The 2015 American Thyroid Association Pediatric Guideline was used as framework for the present guideline. Areas of discordance were identified, and clinical questions were formulated. The expert panel members discussed the evidence and formulated recommendations based on the latest evidence and expert opinion. Children with a thyroid nodule or DTC require expert care in an experienced center. The present guideline provides guidance for healthcare professionals to make well-considered decisions together with patients and parents regarding diagnosis, treatment, and follow-up of pediatric thyroid nodules and DTC.

Aggressive variants of follicular cell-derived thyroid carcinoma: an overview

PURPOSE

The incidence of thyroid carcinoma has increased globally in the past years. Papillary thyroid carcinoma (PTC) is the most frequent neoplasm of the thyroid gland comprehending the 90% of the thyroid carcinoma and has an indolent clinical behaviour. However, some variants of follicular cell-derived thyroid carcinoma, including variants of classic of PTC, have been identified that show a more aggressive biological behaviour. An accurate diagnosis of these entities is crucial for planning a more aggressive treatment and improving patients' prognosis of patients. The aim of this review is to present the main clinical, histological, and molecular features of aggressive variants of follicular cell-derived thyroid carcinoma, and to provide useful histological parameters for determining the most suitable therapeutic strategy for patients affected by these forms.

RESULTS

Variants of classic PTC such as the diffuse sclerosing variant (DSV), the tall cell variant (TCV), the columnar cell variant (CCV), the solid/trabecular variant (STV) and the hobnail variant (HV), and other variants of follicular cell-derived thyroid carcinoma, such as poorly differentiated thyroid carcinoma (PDTC), and anaplastic thyroid carcinoma (ATC), are associated with aggressive behaviour.

CONCLUSIONS

The correct identification and diagnosis of aggressive variants of follicular cell-derived thyroid carcinoma is important, as they allow the clinician to adopt the most refined therapeutic strategies in order to the survival of the patients.

Papillary and medullary thyroid carcinomas coexisting in the same lobe, first suspected based on fine-needle aspiration cytology: a case report

Because different types of thyroid malignancies have distinct embryological origins, coexisting tumors are rarely observed. We describe a coexisting papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma (MTC) first suspected by fine-needle aspiration cytology (FNAC). A 57-year-old female presented with an irregular mass in the right thyroid lobe. The cytopathologic findings of fine-needle aspiration showed two components: a papillary-like arrangement consisting of cells with pale enlarged nuclei indicative of PTC and loose clusters comprised of oval cells with granular chromatin indicative of MTC. The diagnosis of a coexisting PTC and MTC was initially confirmed by calcitonin immunocytochemistry and later after total thyroidectomy. Although some surgical case reports of PTC and MTC coexisting in either the same or different lobes have been documented, a case suspected by FNAC before the surgery has rarely been reported. Because appropriate treatment and prognosis of PTC and MTC are different, cytopathologists should be aware of this rare entity.

A deep learning–based algorithm for tall cell detection in papillary thyroid carcinoma

Introduction

According to the World Health Organization, the tall cell variant (TCV) is an aggressive subtype of papillary thyroid carcinoma (PTC) comprising at least 30% epithelial cells two to three times as tall as they are wide. In practice, applying this definition is difficult causing substantial interobserver variability. We aimed to train a deep learning algorithm to detect and quantify the proportion of tall cells (TCs) in PTC.

Methods

We trained the deep learning algorithm using supervised learning, testing it on an independent dataset, and further validating it on an independent set of 90 PTC samples from patients treated at the Hospital District of Helsinki and Uusimaa between 2003 and 2013. We compared the algorithm-based TC percentage to the independent scoring by a human investigator and how those scorings associated with disease outcomes. Additionally, we assessed the TC score in 71 local and distant tumor relapse samples from patients with aggressive disease.

Results

In the test set, the deep learning algorithm detected TCs with a sensitivity of 93.7% and a specificity of 94.5%, whereas the sensitivity fell to 90.9% and specificity to 94.1% for non-TC areas. In the validation set, the deep learning algorithm TC scores correlated with a diminished relapse-free survival using cutoff points of 10% (p = 0.044), 20% (p < 0.01), and 30% (p = 0.036). The visually assessed TC score did not statistically significantly predict survival at any of the analyzed cutoff points. We observed no statistically significant difference in the TC score between primary tumors and relapse tumors determined by the deep learning algorithm or visually.

Conclusions

We present a novel deep learning–based algorithm to detect tall cells, showing that a high deep learning–based TC score represents a statistically significant predictor of less favorable relapse-free survival in PTC.

Metastatic lung carcinoma in thyroid aspirates: A case series and literature review illustrating diagnostic challenges

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common primary malignant thyroid neoplasm and malignant diagnosis in thyroid aspirates. Metastatic adenocarcinoma of lung is an under-recognized mimicker which overlaps cytomorphologically and immunocytochemically with PTC. This case series reviews thyroid aspirates of metastatic lung carcinomas, aiming to address the similarities and methods of differentiating this entity from PTC.

METHODS

Thyroid aspirates of metastatic lung carcinomas were obtained by a computerized search. Clinico-cytological features and ancillary test results were reviewed. Literature review was performed for published cases of metastatic lung carcinomas in thyroid aspirates.

RESULTS

A total of 14 cases were found, including nine adenocarcinomas, three TTF1-positive non-small cell lung carcinomas (NSCLCs), one small cell carcinoma and one squamous cell carcinoma. The adenocarcinomas and TTF1-positive NSCLCs displayed PTC-like features including papillae/papillary-like fronds (n=6/12, 50%), nuclear grooves (n=5/12, 41.7%) and inclusions (n=1/12, 8.3%), chromatin clearing (n=3/12, 25%), calcifications (n=3/12, 25%) and multinucleated giant cells (n=2/12, 16.7%). Useful distinguishing features observed were prominent nucleoli, coarse chromatin, mitosis, and necrosis. TTF-1 immunocytochemistry was positive in most cases (n=5/6, 83.3%), while PAX8 and thyroglobulin were consistently negative. EGFR exon 19 deletion was detected on cell block preparation in a single case, corresponding to its lung primary. Literature search yielded 84 cases of metastatic malignancies, with lung carcinomas comprising of 3.6%-33.3% in case series of metastatic malignancies.

CONCLUSION

Metastatic adenocarcinoma of lung and PTC share significant cytomorphological and immunocytochemical similarities. A high degree of caution, meticulous clinico-cytological assessment and prudent use of ancillary techniques is necessary to avoid potential misdiagnosis.

Differentiation of Thyroid Nodules (C-TIRADS 4) by Combining Contrast-Enhanced Ultrasound Diagnosis Model With Chinese Thyroid Imaging Reporting and Data System

Objectives

To establish a contrast-enhanced ultrasound (CEUS) diagnostic schedule by CEUS analysis of thyroid nodules of C-TIRADS 4. To establish a CEUS-TIRADS diagnostic model to differentiate thyroid nodules (C-TIRADS 4) by combining CEUS with Chinese thyroid imaging reporting and data system (C-TIRADS).

Methods

A total of 228 thyroid nodules (C-TIRADS 4) were estimated by CEUS. The arrival time, enhancement degree, enhancement homogeneity, enhancement pattern, enhancement ring, and wash-out time were analyzed in CEUS for all of the nodules. Multivariate factors logistic analysis was performed and a CEUS diagnostic schedule was established. If the nodule had a regular hyper-enhancement ring or got a score of less than 2 in CEUS analysis, CEUS-TIRADS subtracted 1 category. If the nodule got a score of 2 in the CEUS schedule, the CEUS-TIRADS category remained the same as before. If the nodule got a score of more than 2 in the CEUS schedule, CEUS-TIRADS added 1 category. When it reflected an absent enhancement in CEUS, the nodule was judged as CEUS-TIRADS 3. All of the C-TIRADS 4 nodules were re-graded by CEUS-TIRADS. We then compare the diagnosis performance of C-TIRADS, CEUS, and CEUS-TIRADS by sensitivity, specificity, and accuracy.

Results

Among the 228 C-TIRADS 4 nodules, 69 were determined as C-TIRADS 4a, 114 were C-TIRADS 4b, and 45 were C-TIRADS 4c. The sensitivity, specificity, and accuracy of C-TIRADS were 93.1%, 55.3%, and 74.6% respectively. The area under the curve was 0.753. Later arrival time, hypo-enhancement, heterogeneous enhancement, centripetal enhancement, and rapid washout were risk factors of malignancy in multivariate analysis. The sensitivity, specificity, and accuracy of CEUS were 78.7%, 87.5%, and 83.3% respectively. The area under the curve was 0.803. By CEUS-TIRADS diagnostic model combining CEUS with C-TIRADS, a total of 127 cases were determined as malignancy (111 were malignant and 16 were benign) and 101 were diagnosed as benign ones (5 were malignant and 96 were benign). The sensitivity, specificity, and accuracy of CEUS-TIRADS were 95.7%, 85.7%, and 92.1% respectively. The area under the curve was 0.916. The diagnostic performance of CEUS-TIRADS was significantly better than CEUS and C-TIRADS. The difference was statistically significant (P<0.05).

Conclusions

The diagnostic schedule of CEUS could get better diagnostic performance than US in the differentiation of thyroid nodules. The CEUS-TIRADS combining CEUS analysis with C-TIRADS could make up for the deficient sensibility of C-TIRADS, showing a better diagnostic performance than US and CEUS.

MicroRNA-203a-3p may prevent the development of thyroid papillary carcinoma via repressing MAP3K1 and activating autophagy

Background

Papillary thyroid carcinoma (PTC) grows slowly but has a great risk of metastasis. MicroRNAs are well known as vital tumor‐related gene regulators. In PTC, the role of miR‐203a‐3p and the underlying mechanisms remain not completely understood.

Methods

We conducted CCK8 assay, wound healing assay, transwell experiment and flow cytometry analyses to investigate the function of miRNA‐203a‐3p. The interaction of miRNA‐203a‐3p with its gene MAP3K1 was characterized by quantitative real‐time polymerase chain reaction, western blotting and luciferase assay.

Results

We found that the levels of miRNA‐203a‐3p were statistically decreased in PTC tissues. When mimics were delivered to TPC‐1 and KTC‐1 cells to upregulate miR‐203a‐3p, it was observed that cell proliferation, metastatic abilities and cell cycle process were prevented but cell apoptosis was enhanced. Furthermore, we proved the interaction between MAP3K1 and miR‐203a‐3p. Intriguingly, similar to miR‐203a‐3p mimics, siMAP3K1 showed a tumor‐suppressive effect, and this effect could be reversed when miR‐203a‐3p was simultaneously inhibited. Finally, selected autophagy‐linked proteins such as LC3 Beclin‐1 were detected and found to be increased when miR‐203a‐3p was upregulated or MAP3K1 was inhibited.

Conclusion

Overall, miR‐203a‐3p inhibits the oncogenic characteristics of TPC‐1 and KTC‐1 cells via suppressing MAP3K1 and activating autophagy. Our findings might enrich the understanding and the therapeutic strategies of PTC.

GATA binding protein 1 recruits histone deacetylase 2 to the promoter region of nuclear receptor binding protein 2 to affect the tumor microenvironment and malignancy of thyroid carcinoma

The tumor microenvironment (TME) and activated angiogenesis in thyroid carcinoma (TC) are critical for tumor growth and metastasis. Nuclear receptor binding protein 2 (NRBP2) has been suggested as a tumor suppressor. This study examines the function of NRBP2 in the progression of TC and the regulatory mechanism. By analyzing bioinformatic tools including GSE165724 dataset and the Cancer Genome Atlas system, we predicted NRBP2 as a poorly expressed gene in TC. Decreased NRBP2 expression was detected in TC tumor tissues and cells. Poor expression of NRBP2 was linked to unfavorable prognosis of patients. GATA binding protein 1 (GATA1) was found as a negative regulator of NRBP2. It recruited histone deacetylase2 (HDAC2) to the NRBP2 promoter to trigger histone deacetylation. NRBP2 overexpression suppressed growth of TC cells, and it reduced expression of TME markers, M2 polarization of macrophages, and angiogenesis in TC. Similar results were reproduced in vivo in nude mice. However, the anti-oncogenic roles of NRBP2 were blocked after further overexpression of GATA1 or HDAC2. In summary, this study demonstrates that GATA1 recruits HDAC2 to the NRBP2 promoter and enhances the TME and angiogenesis in TC cells.

CDK9 is up-regulated and associated with prognosis in patients with papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy but shows excellent prognosis. We investigated the clinical significance of cyclin-dependent kinase 9 (CDK9) in patients with PTC.This prospective observational study included 192 patients with PTC, who visited our hospital between August 2018 and February 2020. We obtained 93 tissue samples from patients with benign thyroid disease during the same period as controls. Immunohistochemical evaluation and reverse transcription-quantitative polymerase chain reaction assay were performed to evaluate CDK9 expression. Patients' demographic and clinical characteristics were analyzed.Delphian lymph node (DLN) metastasis in patients with PTC was associated with clinicopathological characteristics. CDK9 expression was up-regulated in patients with PTC, and those with DLN metastasis showed higher CDK9 expression. We also observed that tumor size, capsule invasion, tumor-node-metastasis classification (TNM) stage, and multifocality were the risk factors for DLN metastasis in patients with PTC. Additionally, CDK9 expression was strongly associated with tumor size, capsule invasion, TNM stage, and multifocality and weakly associated with the number of metastatic DLN.CDK9 is up-regulated in patients with PTC and associated with prognosis in these patients.

Clinical-Pathological Features and Treatment Outcome of Patients With Hobnail Variant Papillary Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) with hobnail areas above 30% is classified as hobnail variant (HVPTC). Although it is widely accepted that HVPTC has a worse outcome than classical PTC, it is unclear whether PTC with hobnail features below 30% is as aggressive as HVPTC. We gathered the largest mono-institutional series of PTC with hobnail areas and HVPTC to evaluate differences in terms of pathological features of aggressiveness, molecular profile, and treatment outcome. A total of 99 PTC with hobnail features above 5% were retrospectively selected; 34 of them met the criteria for HVPTC (0.4% of all PTC diagnosed at our institution). All tumors showed high rates of extra-thyroidal extension (40.4%), lymph node metastasis (68.1% of patients with lymphadenectomy), and vascular emboli (49.5%), with no differences according to the 30% cutoff. On the other hand, distant metastases were present in HVPTC only (9.4%). Also, advanced age, advanced disease stage, and TERT promoter mutation were associated with HVPTC. More than half of the patients with follow-up had structural or biochemical persistence after 1 year from surgery. Structural persistence was significantly more common in patients with HVPTC (37.5% vs. 8.7%), while no differences were observed considering structural and biochemical persistence together. The presence of hobnail features identifies locally aggressive tumors, and, consequently, it should be always acknowledged in the pathological report. However, tumors with more than 30% hobnail areas frequently present TERT promoter mutations, advanced disease stage, and structural persistence after radioiodine ablation.

Activation of the TGF-β1/Smad signaling by KIF2C contributes to the malignant phenotype of thyroid carcinoma cells

Kinesin family member 2C (KIF2C) has been identified as a potential oncogene in various types of human cancers; however, the role of KIF2C in thyroid cancer has not yet been elucidated. Quantitative real-time polymerase chain reaction and western blotting were employed for gene expression analysis. Cell Counting Kit-8 and ethynyl-2'-deoxyuridine assays were performed to examine cell proliferation. Cell migration and invasion were assessed by wound-healing and transwell invasion assays. Results showed that KIF2C expression was upregulated in thyroid carcinoma cell lines. In addition, upregulation of KIF2C promoted the proliferation, migration, and invasion of thyroid carcinoma cells, while downregulation of KIF2C exerted the opposite effects. Overexpression of KIF2C induced the activation of transforming growth factor-β1 (TGF-β1)/Smad signaling in thyroid carcinoma cells. However, inhibition of TGF-β1/Smad signaling through silencing TGF-β1 attenuated the promoting effects of KIF2C overexpression on the malignant phenotype of thyroid carcinoma cells. Besides, overexpression of TGF-β1 suppressed the inhibitory effect of KIF2C knockdown on the proliferation and metastasis of thyroid carcinoma cells. In conclusion, our findings demonstrated that KIF2C contributed to the malignant phenotype of thyroid carcinoma cells by inducing the activation of TGF-β1/Smad signaling, thus uncovering a novel mechanism for thyroid carcinoma progression.

Tall cell percentage alone in PTC without aggressive features should not guide patients' clinical management

CONTEXT

Recent diagnostic criteria updates of the tall cell variant of papillary thyroid carcinoma (TCPTC) by the World Health Organization (WHO) have determined the inclusion of tumors with 30% to 49% of tall cells. However, the impact of tall cell percentage on papillary thyroid carcinoma (PTC) patients' prognosis is still debated.

OBJECTIVE

We aimed to evaluate whether tall cell percentage affects patient outcome in the absence of aggressive features.

METHODS

Rates of aggressive features, recurrence-free survival (RFS), and distant RFS (5-year median follow-up) were compared among tumors with less than 30%, 30% to 49% and at least 50% tall cells. We also evaluated the impact of the new tall cell cutoff on patient management.

RESULTS

Overall, 3092 tumors (15.7% of all PTCs) were collected: A total of 792 PTCs had less than 30%, 503 had 30% to 49%, and 1797 had 50% or more tall cell areas. With the new WHO definition, the number of TCPTCs increased by 28%. There were no differences in recurrence rates according to tall cell percentage. The coexistence of BRAF and TERT promoter mutations predicted a worse RFS. Considering the new definition of TCPTC, the level of risk according to the American Thyroid Association increased from low to intermediate in 4.2% of cases. However, the recurrence rate within this subgroup was comparable to low risk.

CONCLUSION

TCPTC and PTC with tall cell areas can be considered as a unique group with similar recurrence risk. However, whenever aggressive features are absent, tumors have a low risk of recurrence independently of tall cell percentage.

PRKAR1A and Thyroid Tumors

Simple Summary

In 2021 it is estimated that there will be 44,280 new cases of thyroid cancer in the United States and the incidence rate is higher in women than in men by almost 3 times. Well-differentiated thyroid cancer is the most common subtype of thyroid cancer and includes follicular (FTC) and papillary (PTC) carcinomas. Over the last decade, researchers have been able to better understand the molecular mechanisms involved in thyroid carcinogenesis, identifying genes including but not limited to RAS, BRAF, PAX8/PPARγ chromosomal rearrangements and others, as well as several tumor genes involved in major signaling pathways regulating cell cycle, differentiation, growth, or proliferation. Patients with Carney complex (CNC) have increased incidence of thyroid tumors, including cancer, yet little is known about this association. CNC is a familial multiple neoplasia and lentiginosis syndrome cause by inactivating mutations in the PRKAR1A gene which encodes the regulatory subunit type 1α of protein kinase A. This work summarizes what we know today about PRKAR1A defects in humans and mice and their role in thyroid tumor development, as the first such review on this issue.

Abstract

Thyroid cancer is the most common type of endocrine malignancy and the incidence is rapidly increasing. Follicular (FTC) and papillary thyroid (PTC) carcinomas comprise the well-differentiated subtype and they are the two most common thyroid carcinomas. Multiple molecular genetic and epigenetic alterations have been identified in various types of thyroid tumors over the years. Point mutations in BRAF, RAS as well as RET/PTC and PAX8/PPARγ chromosomal rearrangements are common. Thyroid cancer, including both FTC and PTC, has been observed in patients with Carney Complex (CNC), a syndrome that is inherited in an autosomal dominant manner and predisposes to various tumors. CNC is caused by inactivating mutations in the tumor-suppressor gene encoding the cyclic AMP (cAMP)-dependent protein kinase A (PKA) type 1α regulatory subunit (PRKAR1A) mapped in chromosome 17 (17q22–24). Growth of the thyroid is driven by the TSH/cAMP/PKA signaling pathway and it has been shown in mouse models that PKA activation through genetic ablation of the regulatory subunit Prkar1a can cause FTC. In this review, we provide an overview of the molecular mechanisms contributing to thyroid tumorigenesis associated with inactivation of the RRKAR1A gene.

Immunohistochemical Analysis of Toll-Like Receptors, MyD88, and TRIF in Human Papillary Thyroid Carcinoma and Anaplastic Thyroid Carcinoma

Purpose

We hypothesized that innate immune response pathways might be involved in thyroid carcinogenesis. To investigate this hypothesis, we aimed at analyzing the expression of several receptors and molecules in the innate immune system in papillary thyroid carcinoma (PTC) and anaplastic thyroid carcinoma (ATC) tissues.

Methods

Of the surgically resected specimens, 11 ATC tissues, 25 PTC tissues, and 8 nodular hyperplasia (NH) tissues were selected and examined for the expression of toll-like receptor (TLR) 2, TLR3, TLR4, TLR5, TLR7, TLR9, the myeloid differentiation primary response gene 88 (MyD88), and toll-interleukin-1 receptor domain-containing adaptor inducing INF-β (TRIF) by immunohistochemistry (IHC).

Results

Several TLRs were expressed in each tissue. TLR3 was strongly expressed in all tissues. In contrast, TLR4 was not detected in any tissues. While TLR5 was moderately expressed in NH but significantly reduced in PTC and ATC, TLR9 was absent in NH tissue but moderately expressed in both PTC and ATC. On MyD88 expression, no significant difference was found between PTC and ATC. TRIF was significantly upregulated in PTC and ATC compared to NH. Surprisingly, PTC and ATC tissues exhibited similar expression patterns of TLRs, MyD88, and TRIF.

Conclusion

These data suggest the involvement of the innate immune system in both PTC and ATC. Specifically, TLR3-mediated TRIF activation was confirmed in PTC and ATC. This provides new insight into thyroid carcinogenesis.

Long Non-coding RNA RUNDC3A-AS1 Promotes Lung Metastasis of Thyroid Cancer via Targeting the miR-182-5p/ADAM9

Long non-coding RNAs (lncRNAs) have been identified as influential indicators in variety of malignancies. Among which, LncRNA RUNDC3A-AS1 is reported to upregulate in thyroid cancer. However, the expression pattern and the pathological function of lncRNA RUNDC3A-AS1 in thyroid cancer is unclear. In this study, we examined the expression levels of lncRNA RUNDC3A-AS1 in the thyroid cancer tissues and cell lines via RT-qPCR analysis. The effects of RUNDC3A-AS1 on thyroid cancer cell metastasis were detected by transwell chamber assay, scratch assay in vitro and lung metastasis model in vivo. The results indicated that RUNDC3A-AS1 was highly expressed in the thyroid cancer tissues and cell lines. Functionally, knockdown of RUNDC3A-AS1 could repress the migration and invasion of thyroid cancer cells in vitro, and inhibit thyroid cancer metastasis to lung in vivo. Mechanistically, RUNDC3A-AS1 served as an inhibitor of miR-182-5p in tumor tissues and cell lines. RUNDC3A-AS1 inhibited the expression of miR-182-5p to increase the expression level of ADAM9, thus further aggravating the malignancy of thyroid cancer. Therefore, the RUNDC3A-AS1/miR-182-5p/ADAM9 axis may be a potential therapeutic target for the treatment of thyroid cancer metastasis.

Long non-coding RNA LINC00488 facilitates thyroid cancer cell progression through miR-376a-3p/PON2

Objective: Long non-coding RNAs (lncRNAs) recently have been identified as influential indicators in a variety of malignancies. The aim of the present study was to identify a functional lncRNA LINC00488 and its effects on thyroid cancer in the view of cell proliferation and apoptosis.

Methods: In order to evaluate the effects of LINC00488 on the cellular process of thyroid cancer, we performed a series of in vitro experiments, including cell counting kit-8 (CCK-8) assay, EdU (5-ethynyl-2′-deoxyuridine) assay, flow cytometry, transwell chamber assay, Western blot and RT-qPCR. The target gene of LINC00488 was then identified by bioinformatics analysis (DIANA and TargetScan). Finally, a series of rescue experiments was conducted to validate the effect of LINC00488 and its target genes on proliferation, migration, invasion and apoptosis of thyroid cancer.

Results: Our findings revealed that LINC00488 was highly expressed in thyroid cancer cell lines (BCPAP, BHP5-16, TPC-1 and CGTH-W3) and promoted the proliferation, migration and invasion, while inhibited the apoptosis of thyroid cancer cells (BCPAP and TPC-1). The results of bioinformatics analysis and dual luciferase reporter gene assay showed that LINC00488 could directly bind to miR-376a-3p and down-regulated the expression level of miR-376a-3p. In addition, Paraoxonase-2 (PON2) was a target gene of miR-376a-3p and negatively regulated by miR-376a-3p. Rescue experiment indicated that LINC00488 might enhance PON2 expression by sponging miR-376a-3p in thyroid cancer.

Conclusion: Taken together, our study revealed that lncRNA LINC00488 acted as an oncogenic gene in the progression of thyroid cancer via regulating miR-376a-3p/PON2 axis, which indicated that LINC00488-miR-376a-3p-PON2 axis could serve as novel biomarkers or potential targets for the treatment of thyroid cancer.

Molecular Pathology of Non-familial Follicular Epithelial-Derived Thyroid Cancer in Adults: From RAS/BRAF-like Tumor Designations to Molecular Risk Stratification

This review addresses the impact of molecular alterations on the diagnosis and prognosis of differentiated thyroid carcinoma (DTC), including papillary, follicular, and well-differentiated carcinoma NOS, as well as oncocytic neoplasms. The molecular characterization of DTC is based upon the well-established dichotomy of BRAF-like and RAS-like designations, together with a remaining third group, less homogeneous, composed of non-BRAF-/non-RAS-like tumors. The role of BRAF V600E mutation in risk stratification is discussed in the clinico-pathological context, namely, staging and invasive features of classic papillary thyroid carcinoma (PTC) and histopathological variants carrying an excellent prognosis (microPTC) or a guarded prognosis, including the aggressive variants tall cell and hobnail cell PTCs. In follicular patterned tumors, namely, follicular thyroid carcinoma (FTC), with or without oncocytic features, the most prevalent molecular alteration are RAS mutations that do not carry prognostic significance. The only genetic alteration that has been proven to play a role in risk stratification of PTC and FTC is TERT promoter (TERTp) mutation.

Fine-Needle Aspiration Cytology and Histological Types of Thyroid Cancer in the Elderly: Evaluation of 9070 Patients from a Single Referral Centre

Simple Summary

Elderly patients have a high prevalence of thyroid nodules, and their management should consider the presence of comorbidities, which are frequent in this age group. In this retrospective monocentric study, we analyzed data of more than 13,000 nodules in order to highlight differences between the elderly and the general population in terms of cytological and histological diagnoses. Thyroid nodules in the elderly are more often benign than in younger patients. Nevertheless, in case of malignancy, follicular-derived well-differentiated tumors are almost always diagnosed in younger patients. Instead, elderly patients more often have tumors with aggressive histotypes. In addition, even in presence of well-differentiated tumors, elderly patients present a higher rate of high-risk pathological features.

Abstract

Background. The prevalence of thyroid nodules increases with age. Their management takes into account the presence of co-morbidities, which are frequent among the elderly. We sought to highlight the differences between the elderly and the general population in cytological and histological diagnoses. Methods. In this retrospective cohort study, we gathered 13,747 nodule data and compared cytological and histological diagnoses between patients aged over 65 years and a control group. Results. Elderly patients had a higher prevalence of cytologically benign nodules and, consequently, they were less frequently subject to surgery. However, there were no differences in terms of malignancy-risk after surgery. At histology, elderly patients often presented aggressive histology such as medullary thyroid carcinoma, poorly-differentiated and anaplastic cancer, tall cell variant of papillary thyroid carcinoma and Hürthle cell carcinoma. Even in presence of well-differentiated cancer, older patients had higher rates of local invasiveness, lateral lymph node involvement and vascular invasion. Conclusion. Thyroid nodules in elderly patients represent a challenging entity since they are very often benign, but, in case of malignancy, aggressive histotypes and high-risk features are more frequent. Therefore, presurgical characterization of nodules in older patients is crucial and might require strict monitoring.

Kin17 facilitates thyroid cancer cell proliferation, migration, and invasion by activating p38 MAPK signaling pathway

Kin17 DNA and RNA binding protein (Kin17) is an extremely conserved nuclear protein that is almost expressed in every type of mammal cells. Recently, Kin17 has been implicated into the regulation of tumorigenesis of diverse human cancers. However, its functions in thyroid cancer (TC) are still largely unexplored. Kin17 mRNA and protein level were tested by qRT-PCR and western blot, respectively. Effects of Kin17 on TC cell proliferation were estimated by colony formation assay and flow cytometry analysis in vitro as well as by in vivo tumor growth experiment. TC cell migratory and invasive capacities were assessed via wound-healing and transwell experiments. Epithelial-mesenchymal transition (EMT)-related proteins (E-cadherin and N-cadherin) and p38 MAPAK signaling pathway-related proteins (p-p38, p38, Cyclin D1, and p27) were examined via western blot. Kin17 was remarkably increased in TC tissue samples and cell lines at both mRNA and protein levels compared to normal tissue and control cell line. Knockdown of Kin17 obviously repressed TC cell proliferation, arrested cell cycle, and inhibited TC cell migration and invasion in vitro, while overexpression of Kin17 produced opposite effects. Kin17 knockdown suppressed p38 MAPK signaling pathway, while Kin17 overexpression activated this pathway. Treatment of p38 agonist (p79350) abolished the repressive effects of sh-Kin17 on TC cell proliferation, migration, and invasion, as well as on p38 pathway. Kin17 knockdown was also found to enhance the sensitivity of Doxorubicin of TC cells. In addition, Kin17 knockdown in vivo also markedly repressed TC tumor growth and p38 pathway. Kin17 functioned as an oncogene of TC by activating p38 MAPK signaling pathway.

Long Non-Coding RNA LUCAT1 Promotes Progression of Thyroid Carcinoma by Reinforcing ADAM10 Expression Through Sequestering microRNA-493

Background

Long non-coding RNA (lncRNA) LUCAT1 has recently been recognized as an oncogene in several malignancies. This study was launched to probe its role in thyroid carcinoma (TC) development and the implicated molecules.

Methods

LUCAT1 expression in TC cell lines and in normal thyroid follicular epithelial cell line Nthy-ori3-1 was determined by RT-qPCR. Binding relationships between LUCAT1 and microRNA (miR)-493, and between miR-493 and a disintegrin and metalloproteinase-10 (ADAM10) were predicted on a bioinformatics system and then validated through luciferase reporter gene assays. Expression of miR-493 and ADAM10 in TC cells was determined. Gain- and loss-of functions of LUCAT1, miR-493 and ADAM10 were performed to explore their influences on the behaviors of TC cells. Xenograft tumors were induced in nude mice for in vivo studies.

Results

LUCAT1 and ADAM10 were highly expressed, while miR-493 was poorly expressed in TC cell lines. LUCAT1 served as a miR-493 sponge to upregulate ADAM10 expression. Silencing of LUCAT1 discouraged proliferation, invasion, and migration but triggered apoptosis of TC cells. By contrast, these changes were abrogated by further miR-493 inhibition or ADAM10 upregulation. The in vitro experiment results were reproduced in vivo. In addition, miR-493 inhibition or ADAM10 overexpression was found to increase the phosphorylation of STAT3 in cells.

Conclusion

This study evidenced that LUCAT1 increases ADAM10 expression through sequestering miR-493, leading to JAK-STAT activation and TC cell growth and metastasis. LUCAT1 and ADAM10 may serve as therapeutic targets for TC treatment.

Knockdown of long non‑coding RNA CCAT2 suppresses the progression of thyroid cancer by inhibiting the Wnt/β‑catenin pathway

Thyroid cancer (TC) is one of the most common malignancies with a high mortality rate. Long non-coding RNA CCAT2 (CCAT2) participates in the occurrence and development of certain human cancers; however, whether it is involved in TC remains unclear. Thus, the present study investigated the role of CCAT2 in TC and the underlying mechanism. CCAT2 expression in both TC tissues and cell lines was examined by reverse transcription-quantitative PCR. CCAT2 expression was silenced in TC cell lines by a specific small interfering (si)RNA against CCAT2 (si-CCAT2). The effects of CCAT2 silencing on TC cell proliferation were detected by CCK-8 and colony formation assays. Cell cycle and apoptosis of the treated TC cells were assessed by flow cytometry. Wound healing and Transwell assays were performed to detect the effects of si-CCAT2 on the migration and invasion of TC cells. Apoptosis-related proteins and Wnt/β-catenin cascade-associated agents were examined by western blotting. The interaction between CCAT2 and the Wnt/β-catenin pathway in the transfected cells was detected by performing a dual-luciferase reporter assay. CCAT2 expression was increased in TC tissue samples and cell lines compared with the controls. Tissue CCAT2 level was associated with T stage and tumor-node-metastasis stage of TC. Silencing CCAT2 inhibited TC cell proliferation, migration and invasion, and promoted TC cell cycle arrest and apoptosis. Furthermore, CCAT2 knockdown suppressed the activity of the Wnt/β-catenin cascade in TC cells treated with lithium chloride. In summary, the present study demonstrated that CCAT2 knockdown suppresses TC progression via inactivating the Wnt/β-catenin cascade, indicating that suppressing CCAT2 and the Wnt/β-catenin signaling pathway may be a promising therapeutic strategy for treating TC.

SOX18 exerts tumor-suppressive functions in papillary thyroid carcinoma through inhibition of Wnt/β-catenin signaling

Sex-determining region on the Y chromosome-related high mobility group box 18 (SOX18) has emerged as a key tumor-related protein in a wide range of human tumors. Yet, the involvement of SOX18 in papillary thyroid carcinoma has not been determined. This study aimed to explore the expression and biological function of SOX18 in papillary thyroid carcinoma. There was a significant decrease in SOX18 expression in papillary thyroid carcinoma tissues compared with that in normal tissues. Low expression of SOX18 was also detected in papillary thyroid carcinoma cell lines and upregulation of SOX18 effectively repressed the proliferative, colony-forming and invasive abilities of papillary thyroid carcinoma cells in vitro. In contrast, knockdown of SOX18 in papillary thyroid carcinoma cells was associated with a significant increase in cell proliferation and invasion. Further studies revealed that SOX18 upregulation was associated with the reduced nuclear accumulation of β-catenin and the downregulation of Wnt/β-catenin signaling in thyroid carcinoma cells. Moreover, inhibition of Wnt/β-catenin signaling markedly attenuated SOX18 knockdown-evoked oncogenic effects in papillary thyroid carcinoma cells. In addition, SOX18 overexpression remarkably retarded the tumor growth of papillary thyroid carcinoma cell-derived xenograft tumors in nude mice. Taken together, these results demonstrate that SOX18 suppresses the proliferation and invasion of papillary thyroid carcinoma by inhibiting Wnt/β-catenin signaling. Our study reveals a tumor-suppressive role of SOX18 in papillary thyroid carcinoma and suggests that SOX18 is an attractive candidate target for treatment of papillary thyroid carcinoma.

Single-cell RNA sequencing reveals the regenerative potential of thyroid follicular epithelial cells in metastatic thyroid carcinoma

Thyroid stimulating hormone deficiency is the cornerstone of treatment for metastatic thyroid cancer. Due to the loss of follicular epithelial cells in thyroid cancer, the thyroid gland degenerates to 85% of its original size. When thyroid stimulating hormone is restored, follicular epithelial cells in thyroid cancer regenerate, which is postulated to be related to stem-like cells. By single cell RNA seq, we found a group of rare thyroid follicular epithelial cells in mouse metastatic thyroid cancer, which expressed stem-like genes (CD44V6⁺ and CD133⁺) and a large number of differentiated cells (CD44V6⁺ and CD24⁺). In mouse and in organoids, the two subsets contribute equally to metastatic thyroid cancer regeneration. The analysis of human metastatic thyroid cancer revealed that the differentiated thyroid follicular epithelial cell subpopulation was similar to that of the stem like epithelial cell subpopulation, and the regeneration potential was also enhanced after thyroid stimulating hormone ablation. Accordingly, we propose that the regeneration of metastatic thyroid cancer is driven by almost all persistent thyroid follicular epithelial cells, not only by few stem-like cells.

Nine Genes Mediate the Therapeutic Effects of Iodine-131 Radiotherapy in Thyroid Carcinoma Patients

Background

Thyroid carcinoma (THCA) is one of the most common malignancies of the endocrine system, which is usually treated by surgery combined with iodine-131 (I¹³¹) radiotherapy.

Aims

This study is aimed at exploring the potential targets of I¹³¹ radiotherapy in THCA.

Methods

The RNA-sequencing data of THCA in The Cancer Genome Atlas database (including 568 THCA samples) was downloaded. The differentially expressed genes (DEGs) between the tumour samples whether or not subjected to I¹³¹ radiotherapy were identified using edgeR package. Using the WGCNA package, the module that was relevant with I¹³¹ radiotherapy was selected. The intersection genes of the hub module nodes and the DEGs were obtained as hub genes, followed by the function and pathway enrichment analyses using the clusterProfiler package. Moreover, the protein-protein interaction (PPI) network for the hub genes was constructed using Cytoscape software. In addition, more important hub genes were analysed with function mining using the GenCLiP2 online tool. The qPCR analysis was used to verify the mRNA expression of more important hub genes in THCA tissues.

Results

There were 500 DEGs (167 upregulated and 333 downregulated) between the two groups. WGCNA analysis showed that the green module (428 nodes) exhibited the most significant correlation with I¹³¹ radiotherapy. A PPI network was built after the identification of 53 hub genes. In the PPI network, CDH5, KDR, CD34, FLT4, EMCN, FLT1, ROBO4, PTPRB, and CD93 exhibited higher degrees, which were mainly implicated in the vascular function. The relative expression of nine mRNAs in the THCA tissues treated with I¹³¹ was lower.

Conclusion

I¹³¹ radiotherapy might exert therapeutic effects by targeting CDH5, KDR, CD34, FLT4, EMCN, FLT1, ROBO4, PTPRB, and CD93 in THCA patients.

Pitfalls in Thyroid Cytopathology

Fine-needle aspiration (FNA) is among the first diagnostic tools used in the evaluation of thyroid nodules. It has the ability to triage patients with benign and malignant lesions, thus defining the optimum clinical and/or surgical management. The Bethesda System for Reporting Thyroid Cytopathology has found worldwide acceptance. Thyroid FNA offers high positive predictive value (97%-99%), with sensitivities and specificities of 65% to 99% and 72% to 100%, respectively. Nonetheless, many potential diagnostic pitfalls exist that can lead to false-positive and/or false-negative results. This article discusses several of the potential pitfalls in the cytologic evaluation of thyroid lesions.

miR-744-5p mediates lncRNA HOTTIP to regulate the proliferation and apoptosis of papillary thyroid carcinoma cells

Papillary thyroid carcinoma (PTC) is the most common malignancy in thyroid. miR-744-5p plays an efficient role in various cancers, but its role in PTC remains unknown. In this work, we aimed to explore the function of miR-744-5p and the mechanism by which miR-744-5p acted in PTC. We observed that miR-744-5p expression was significantly declined in PTC tissues and cell lines. The high level of miR-744-5p is significantly associated with a better clinical picture of PTC patients. Overexpression of miR-744-5p inhibited the proliferation, arrested the cell cycle, and promoted the apoptosis in PTC cells. Oppositely, down-regulation of miR-744-5p reversed the above tendencies. We also found that miR-744-5p down-regulated its downstream genes c-myc and attenuated cell proliferation induced by c-myc. Long non-coding RNA (lncRNA) HOTTIP was found to be up-regulated and to act as an oncogene in PTC. In this study, miR-744-5p bound to HOTTIP and was negatively regulated by HOTTIP. In conclusion, miR-744-5p acts as a tumor suppressor to inhibit proliferation and promotes the apoptosis of PTC cells via targeting c-myc. Moreover, miR-744-5p expression interferes with lncRNA HOTTIP ability to promote proliferation and downregulate apoptosis in papillary thyroid carcinoma.

Signification of forkhead box A1 (FOXA1) expression in thyroid cancers

BACKGROUND

Forkhead box A1 (FOXA1) plays an important role in several tumors. This study investigated the potential role of FOXA1 expression in thyroid tumors. We conducted a retrospective study of 110 thyroid lesions and tumors diagnosed during 1995-2018. The expression of FOXA1 was analyzed by immunohistochemistry on archival material.

RESULTS

No FOXA1 immunostaining was observed in all cases of Graves' disease, Hashimoto's disease, multi-nodular goiter, and adenoma. FOXA1 expression was absent as well in all papillary and follicular carcinomas, Hurthle cell carcinoma, and undifferentiated sarcoma. Only three anaplastic carcinomas exhibited focally FOXA1 staining. However, FOXA1 was expressed in all medullary carcinomas. No significant correlation was found with all clinicopathological features (p > 0.05 for all). The pattern of FOXA1 staining was similar to that of calcitonin and chromogranin A (p = 0.04 and p = 0.003, respectively).

CONCLUSIONS

FOXA1 is expressed mostly in all medullary thyroid carcinomas. Hence, FOXA1 could serve as an additional marker for refining the diagnosis of medullary thyroid carcinoma.

Transoral endoscopic selective lateral neck dissection for papillary thyroid carcinoma: a pilot study

BACKGROUND

Transoral endoscopic thyroid surgery via the vestibular approach (TOETVA) has been gradually accepted worldwide due to its scar-free effect on the neck. Even central cervical lymphadenectomy has been performed in some cases of papillary thyroid carcinoma (PTC). However, there are few reports involving lateral neck dissection with TOETVA. In this study, we attempted to perform selective lateral neck dissection (SLND) for PTC via a transoral vestibular approach.

METHODS

This prospective study was conducted from January 2016 to December 2018 in twenty PTC patients with unilateral T1 tumors without capsular invasion and patients with abnormal level III and IV lymph nodes who underwent SLND via a transoral vestibular approach.

RESULTS

Endoscopic surgery was successfully accomplished in all 20 PTC patients. The mean age was 29.2 ± 5.5 (20-41) years. The mean operation time was 146.0 ± 18.7 (114-193) min. The average postoperative hospital stay was 6.8 ± 1.3 (5-10) days. The mean number of removed nodes was 7.4 ± 2.5 (4-12) in the central neck and 10.9 ± 2.8 (6-16) in the lateral neck, and the positive yield amounts were 2.0 ± 1.2 (0-4) and 2.7 ± 1.9 (0-6), respectively. No major complications occurred except for 1 case of transient unilateral recurrent laryngeal nerve palsy and two cases of effusion in the operative area. No evidence of persistent or recurrent disease was observed in these patients during a mean follow-up of 24.3 ± 9.1 (6-36) months. The cosmetic results and protection of personal privacy of this procedure were excellent.

CONCLUSION

Endoscopic SLND via the transoral vestibular approach is feasible, safe, and effective for selected PTCs. A multicenter large comparative study is necessary.