Classic papillary thyroid carcinoma with tall cell features and tall cell variant have similar clinicopathologic features

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.

The Impact of BRAF V600E Mutation Allele Frequency on the Histopathological Characteristics of Thyroid Cancer

BACKGROUND

A BRAF V600E mutation in papillary thyroid cancer (PTC) has been shown to be associated with aggressive behavior. Nevertheless, not all BRAF V600E PTCs behave aggressively. Allele frequency (AF) is the number of mutated molecules divided by the total number of wild-type molecules at a specific location in the genome. The relationship between BRAF V600E AF and the histopathological features of thyroid malignancies is not well understood. We hypothesized that the BRAF V600E AF will correlate directly with aggressive histopathological behavior. The aim of this study was to examine this relationship.

METHODS

A retrospective chart review was performed for patients treated for BRAF V600E thyroid malignancies from 2019 to 2022 at McGill University tertiary care hospitals (n = 317). Patients with BRAF V600E-positive malignancies that included information on AF were included (n = 44). The correlation between AF and tumor histopathological features was analyzed.

RESULTS

Out of the 44 nodules with a BRAF V600E mutation, those with aggressive features of PTC had a mean AF of 25.8%, which was significantly higher than the non-aggressive group with a mean AF of 10.25% (p = 0.020). Additionally, there was a statistically significant difference in mean AF between patients with a positive sentinel LN (29%) and those with a negative sentinel LN (17.8%) (p = 0.021). Classical PTC was present in 29.5% (13/44) of nodules, with a mean AF of 15.6%. The tall cell subtype was found in 64% (28/44) of nodules, with a mean AF of 23%. Solid and hobnail subtypes were less common in this study, and there was no statistically significant relationship between AF and histopathological subtypes (p = 0.107). Nodules smaller than 1cm had a mean AF of 13.3%, while nodules ranging from 1 2cm had a mean AF of 20.6%, and those larger than 2cm had a mean AF of 27.7%. However, no statistical difference was observed between AF and nodule size (p = 0.160).

CONCLUSION

In this study, BRAF V600E mutations in conjunction with AF help to determine whether thyroid malignancies will display aggressive behavior. This pre-operative finding can help thyroid specialists to determine the extent of thyroidectomy and whether lymph node dissection is required.

A novel nomogram for identifying high-risk patients among active surveillance candidates with papillary thyroid microcarcinoma

Objective

Active surveillance (AS) has been recommended as the first-line treatment strategy for low-risk (LR) papillary thyroid microcarcinoma (PTMC) according to the guidelines. However, preoperative imaging and fine-needle aspiration could not rule out a small group of patients with aggressive PTMC with large-volume lymph node micro-metastasis, extrathryoidal invasion to surrounding soft tissue, or high-grade malignancy from the AS candidates.

Methods

Among 2,809 PTMC patients, 2,473 patients were enrolled in this study according to the inclusion criteria. Backward stepwise multivariate logistic regression analysis was used to filter clinical characteristics and ultrasound features to identify independent predictors of high-risk (HR) patients. A nomogram was developed and validated according to selected risk factors for the identification of an HR subgroup among "LR" PTMC patients before operation.

Results

For identifying independent risk factors, multivariable logistic regression analysis was performed using the backward stepwise method and revealed that male sex [3.91 (2.58-5.92)], older age [0.94 (0.92-0.96)], largest tumor diameter [26.7 (10.57-69.22)], bilaterality [1.44 (1.01-2.3)], and multifocality [1.14 (1.01-2.26)] were independent predictors of the HR group. Based on these independent risk factors, a nomogram model was developed for predicting the probability of HR. The C index was 0.806 (95% CI, 0.765-0.847), which indicated satisfactory accuracy of the nomogram in predicting the probability of HR.

Conclusion

Taken together, we developed and validated a nomogram model to predict HR of PTMC, which could be useful for patient counseling and facilitating treatment-related decision-making.

Papillary Thyroid Carcinomas with Tall Cell Features: An Intermediate Entity between Classic and Tall Cell Subtypes

BACKGROUND While the diagnosis of papillary thyroid carcinomas with tall cell features (PTCtcf) is often made for carcinomas with histologic features intermediate between classic and tall cell subtypes of PTC (tcPTC), its comparative signature to that of either tcPTC or classic PTC is less clear. The objective of this study was to perform an integrative clinicopathologic and genomic analysis elucidating the spectrum of tcPTC, PTCtcf and classic PTC. METHODS We analyzed all consecutive patients with tcPTC and PTCtcf evaluated at a tertiary academic referral center between 2005-2020, as well as a comparative cohort of classic PTC, in a retrospective observational cohort analysis. Clinicopathological data were compared among the three groups, including progression-free survival (PFS), recurrent/persistent disease, and a negative composite outcome of death, progression, or need for advanced therapy. To specifically understand differences between tcPTC and PTCtcf, targeted next-generation sequencing (NGS) was performed in a subset of these cohorts. RESULTS A total of 292 patients were analyzed (81 tcPTC, 65 PTCtcf, 146 classic PTC). Thirteen percent tcPTC vs. 8% PTCtcf vs. 1% classic PTC had advanced AJCC stage (p=0.002). Similarly, macroscopic extrathyroidal extension was observed in 38% of tcPTC, 14% of PTCtcf and 12% of classic PTC (p<0.001). The 5-year PFS was 76.5%, 81.5% and 88.3% for tcPTC, PTCtcf and classic PTC, respectively, while the rates of the negative composite outcome 40.2% for tcPTC, 20.7% for PTCtcf and 11.2% for classic PTC (p<0.001). In a multivariable Cox regression analysis, the negative composite outcome was independently associated with tcPTC [HR 4.3 95% CI (1.1-16.1), p=0.03]. tcPTC demonstrated substantially more hotspot TERT promoter mutations than PTCtcf (44% vs. 6%, p=0.012). CONCLUSIONS Our study demonstrates a continuum of disease-specific risk of PTC, pointing at PTCtcf as an intermediate entity between tcPTC and classic PTC. These data provide a more refined understanding of risk at time of presentation, while better elucidating the diversity of genomic drivers.

CD56 Expression in Papillary Thyroid Carcinoma Is Highly Dependent on the Histologic Subtype: A Potential Diagnostic Pitfall

Loss of CD56 expression has been regarded as a diagnostic marker of papillary thyroid carcinoma (PTC). However, certain variants of PTC can aberrantly express CD56. Using a digital image analysis tool, we evaluated H-scores of CD56 immunostaining in 216 thyroid tumors. The H-score of the CD56 of all PTCs was lower than that of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) (P<0.001). The H-scores of CD56 were lower in classic PTC, the infiltrative follicular variant, and the diffuse sclerosing variant than in other PTC variants (P<0.001), whereas the H-scores were higher in tall cell variant, Warthin-like variant, and cribriform-morular variant than in classic PTC (P<0.001). The optimal cutoff value of H-scores for the CD56 expression was 180 for differentiating the NIFTP from the follicular adenoma and 30 for the differential diagnosis of NIFTP and infiltrative follicular variant PTC. CD56 expression is predominantly lost in classic and infiltrative follicular variants of PTCs and more preserved in the other histologic subtypes of PTC and NIFTP. CD56 is particularly useful for differentiating PTC from follicular-pattern thyroid neoplasms, but the aberrant expression in uncommon variants of PTC could be a diagnostic pitfall.

Deep Neck Infection: Atypical Presentation of Papillary Thyroid Cancer

Deep neck infection is defined as an infectious process in the potential spaces and fascial plane of the neck which may result in a fatal complication. Prompt drainage and broad-spectrum antibiotics are the mainstays of treatment. Deep neck infection as the initial presentation of primary head and neck cancer is not common. Nevertheless, head and neck squamous cell carcinoma is the most common primary head and neck cancer, which could present with cervical metastasis and subsequently becomes infected. Papillary thyroid cancer has a naturally indolent course, and most patients present with a thyroid nodule. However, deep neck infection could be an uncommon presentation of papillary thyroid cancer which may obscure the diagnosis of underlying malignancy. This case report aims to present a rare presentation of papillary thyroid cancer which needs meticulous evaluation. Moreover, the pathological examination should be performed in all cases of deep neck infection for early detection and management of underlying papillary thyroid cancer.

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.

A population-based study of the three major variants of papillary thyroid carcinoma

Objective

To explore the clinicopathological features and relative prognostic risks of the three major variants of papillary thyroid carcinoma (PTC).

Methods

We retrospectively analyzed the clinicopathological characteristics and prognoses of patients with the three major PTC variants, conventional papillary thyroid carcinoma (CPTC), follicular-variant papillary carcinoma (FVPTC), and tall-cell papillary thyroid carcinoma (TCPTC), based on data from the Surveillance, Epidemiology, and End Results database from 2005 to 2009.

Results

A total of 29,555 patients were enrolled. In terms of their demographic and clinicopathological characteristics, TCPTC had the highest prevalence of older patients, men, patients with locally advanced stage (T stage and N stage), and mortality, while FVPTC had the lowest prevalence in relation to these factors. The three variants differed significantly in terms of 5-year overall survival and 5-year disease-specific survival. Cox regression analysis identified male sex, age ≥45 years, and higher American Joint Committee on Cancer and TNM stage as independent factors predicting a poor prognosis in relation to both overall and disease-specific survival.

Conclusions

CPTC, FVPTC, and TCPTC have different clinicopathological characteristics and prognoses, indicating the need for different treatment strategies for these three variants of PTC.

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.

Cartilage oligomeric matrix protein affects the biological behavior of papillary thyroid carcinoma cells by activating the PI3K/AKT/Bcl-2 pathway

Objective: To explore the effect of cartilage oligomeric matrix protein (COMP) on papillary thyroid carcinoma (PTC).

Methods: COMP expression levels in PTC tissues and matched adjacent normal tissues were measured using tissue microarrays. Human PTC cells were cultured and transduced with lentiviral short hairpin RNA against COMP (COMP-shRNA), a negative control (NC) shRNA, or mock transfected (Control). We used the Cell Counting Kit-8, performed colony formation assays, wound healing assays, Transwell invasion assays, flow cytometry, and measured the expression of apoptosis-related proteins at the mRNA and protein levels to explore the effects of COMP on the biological behavior of PTC cells and to discover the specific signaling pathway involved in these processes.

Results: COMP expression was significantly higher in PTC tissues than in adjacent normal tissues. At the cellular level, COMP promoted cell migration, increased the invasiveness of PTC cells, and inhibited apoptosis. However, differences in cell proliferation were only observed within 72 hours. At the same time, colony formation assays showed that silencing COMP inhibited the proliferation of PTC cells. We also found that COMP regulated the behavior of PTC cells by activating the PI3K/AKT/Bcl-2 pathway.

Conclusions: COMP is upregulated in PTC, which enhances cancer cell invasion and inhibits apoptosis, contributing to the development and progression of PTC. Thus, COMP may serve as a new biomarker for PTC.

Updates in the Pathologic Classification of Thyroid Neoplasms: A Review of the World Health Organization Classification

Advances in medical sciences and evidence-based medicine have led to momentous changes in classification and management of thyroid neoplasms. Much progress has been made toward avoiding overdiagnosis and overtreatment of thyroid cancers. The new 2017 World Health Organization (WHO) classification of thyroid neoplasms updated the diagnostic criteria and molecular and genetic characteristics reflecting the biology and behavior of the tumors, and newly introduced the category of borderline malignancy or uncertain malignant potential. Some neoplasms were subclassified, renamed, or redefined as a specific entity. This review introduces changes in the fourth edition WHO classification of thyroid tumors and updates the contemporary diagnosis and classification of thyroid tumors. We also discuss several challenges with the proposal of new diagnostic entities, since they have unique histopathologic and molecular features and clinical relevance.

Contemporary evaluation and management of tall cell variant of papillary thyroid carcinoma

PURPOSE OF REVIEW

The purpose of this review is to describe the contemporary evaluation and management of tall cell variant of papillary thyroid carcinoma with an emphasis on the clinical features.

RECENT FINDINGS

Tall cell variant of papillary thyroid carcinoma is the most common aggressive subtype. Within the last few years, the diagnostic criteria for this entity have evolved. Studies have elucidated a better understanding of the clinical implications and pathophysiology of this variant. In this review, the studies presented reflect cumulative and aggregated data from metaanalyses, systematic reviews, and large database investigations utilizing the current diagnostic criteria.

SUMMARY

Overall, tall cell variant of papillary thyroid carcinoma represents an aggressive subtype of well-differentiated thyroid carcinoma with more prevalent high-risk features and a poorer clinical outcome.

Papillary Thyroid Cancer-Aggressive Variants and Impact on Management: A Narrative Review

Introduction

Aggressive variants of papillary thyroid cancer (PTC) have been described with increasing frequency. These variants include diffuse sclerosing variant, tall cell variant, columnar cell variant, solid variant, and hobnail variant.

Methods

We have performed a review of the more aggressive variants of PTC with respect to main characteristics, histological and molecular features, and the consequences that the knowledge of these variants should have in the treatment of the patients.

Results

At the present time, we do not know the prognostic value of these aggressive PTC variants. The extent of the surgical treatment and adjuvant therapy necessary should be decided on the basis of the extent of the tumor at presentation and the opinion of experienced clinicians.

Conclusion

These aggressive variants should be known by clinicians, to avoid underdiagnosis, and treated according to the latest recommendations in the literature.

The evolving concept of aggressive histological variants of differentiated thyroid cancer

It is recommended by current clinical guidelines that pathologists identify and report aggressive histological variants of differentiated thyroid cancer (e.g., tall cell, columnar cell, and hobnail variants of papillary thyroid carcinoma; widely invasive follicular thyroid carcinoma). This review analyzes the historical evolution of these entities and highlights unresolved issues with respect to the diagnostic criteria for these tumors.

[Histopatological and molecular genetic characteristics of clinically aggressive variants of papillary thyroid carcinoma]

Papillary carcinoma is the most commonly diagnosed form of well-differentiated thyroid cancer that is generally characterized by a favorable prognosis. However, a number of relatively rare variants of this tumor, such as papillary carcinoma of high cells, papillary carcinoma of columnar cells, a diffuse sclerosing variant and recently described cancer of shoe nail cell type, are characterized by a less favorable clinical course, a high frequency of distant metastasis, and relatively low overall and relapse-free survival rates. In this connection, it is important to recognize these options at the stage of a primary morphological study. This review of the literature considers the morphological, clinical and molecular genetic features of the above variants of papillary thyroid carcinoma.

Tall Cell Variant of Papillary Thyroid Carcinoma: Impact of Change in WHO Definition and Molecular Analysis

The morphologic criteria for tall cell variant (TCV) of papillary thyroid carcinoma (PTC) were modified in the 2017 WHO Classification of Tumors of Endocrine Organs, with a decrease in the requirements for both the height of cells and in the percentage of tumor demonstrating a tall cell morphology. The aim of this study was to determine if the change in criteria would result in a significant increase in the percentage of tumors that meet criteria for TCV. In addition, we evaluated the correlation between morphology, molecular alterations, and clinical behavior of TCV. We studied three cohorts to evaluate the above stated questions. The first cohort was comprised of 97 PTC consecutively resected over a 12-month period that were originally diagnosed as classic PTC, PTC with tall cell features, or TCV. Tumor slides of each case were reviewed to determine the percentage of the tall cell component (< 30%, 30-49%, and > 50%) and the height of the cells in this component. This cohort was evaluated to determine if the change in WHO criteria would result in a significant increase in the percentage of tumors that meet criteria for TCV. Our second cohort consisted of nine consecutively resected PTC with a tall cell component > 30% (with tall cells defined as at least 2-3× as tall as wide) that had molecular characterization through a targeted, next-generation sequencing (NGS) assay. The molecular characteristics were correlated with the percentage of the tall cell component. Finally, a third cohort comprised of seven clinically aggressive TCV (defined as those with T4 disease, disease recurrence, or subsequent tumor dedifferentiation) was evaluated to determine histologic and molecular characteristics. In cohort 1, the number of cases classified as TCV increased significantly with the change in definition of TCV: 8 (8%) cases met the previous criteria for TCV (cells 3× as tall as wide in > 50% of the tumor), whereas 24 (25%) cases met the new 2017 WHO criteria (cells 2-3× as tall as wide in > 30% of the tumor) (p = 0.0020). Molecular analysis of cohort 2 revealed that all 9 cases harbored a BRAF V600E mutation. Pathogenic secondary mutations were absent in cases with < 50% tall cells, but they were detected in 2 (33%) of 6 cases with > 50% tall cells (2 cases with TERT promoter mutations, including 1 that also had an AKT2 mutation). Histologic and molecular analysis of the clinically aggressive cohort (cohort 3), revealed that all cases had > 50% tall cells and 3 (43%) had secondary oncogenic mutations (all TERT promoter mutations). We found that the modified morphologic criteria put forth in the 2017 WHO tripled the number of cases that would be classified as TCV. Moreover, clinically aggressive tumors and those harboring secondary oncogenic mutations all had a tall cell component > 50%. Additional large multi-institutional studies incorporating clinical outcome and molecular data would be valuable to determine the best histologic definition of TCV.

Clinically Relevant Prognostic Parameters in Differentiated Thyroid Carcinoma

Although differentiated thyroid carcinomas typically pursue an indolent clinical course, it is important to identify the subset of tumors that are most likely to behave aggressively so that patients with these tumors are counseled and treated appropriately. Extent of disease is fundamental to the prognostication for differentiated thyroid carcinoma; however, there are additional histologic features of the tumor separate from extent of disease that have been shown to affect clinical course. This review will start with a discussion of aggressive variants of papillary thyroid carcinoma, move to the prognostic significance of vascular invasion in follicular thyroid carcinoma, and finish with a discussion of Hürthle cell carcinoma, with an emphasis on why it is not considered a subtype of follicular thyroid carcinoma in the 2017 WHO Classification of Tumors of Endocrine Organs.

Prediction of novel target genes and pathways involved in tall cell variant papillary thyroid carcinoma

BACKGROUND

Tall cell variant papillary thyroid carcinoma (TCPTC) is reportedly associated with aggressive clinicopathological parameters and poor outcomes; however, the molecular mechanisms underlying TCPTC remain poorly understood.

METHODS

The gene mutation types and mRNA expression profiles of patients with TCPTC were obtained from The Cancer Genome Atlas (TCGA) database. Differentially expressed genes (DEGs) were identified. Pathways in the interaction network and the diagnostic approaches of candidate markers for TCPTC were investigated.

RESULTS

BRAF mutation was particularly prevalent in TCPTC with a mutation frequency of 78%. TCPTC was associated with a patient age >45 years, tumor multifocality, extrathyroidal extension, a higher T stage, advanced AJCC TNM stages, BRAF V600E mutation, and poor disease-free survival. We identified 4138 TCPTC-related DEGs and 301 TCPTC-specific DEGs. Intriguingly, the gene expression pattern revealed that the dysregulated levels of both putative oncogenes and tumor suppressors in TCPTC were higher than those in classical/conventional variant PTC (cPTC). Functional enrichment analyses revealed that these DEGs were involved in several cancer-related pathways. A protein-protein interaction (PPI) network was constructed from the 301 TCPTC-specific DEGs, and 3 subnetworks, and 8 hub genes were verified. Receiver operating characteristic (ROC) analyses revealed that 6 hub genes, including COL5A1, COL1A1, COL10A1, COL11A1, CCL20, and CXCL5, could be used not only for the differential diagnosis of PTC from normal samples, but also for the differential diagnosis of TCPTC from cPTC samples.

CONCLUSIONS

Our study might provide further insights into the investigations of the tumorigenesis mechanism of TCPTC and assists in the discovery of novel candidate diagnostic markers for TCPTC.

Papillary thyroid carcinoma with tall cell features is as aggressive as tall cell variant: a meta-analysis

There are still ongoing debates as to which cut-off percentage of tall cell (TC) should be used to define tall cell variant (TCV) papillary thyroid carcinoma (PTC). In this meta-analysis, we aimed to investigate the clinicopathological significance of PTC with tall cell features (PTC-TCF, PTC with 10-50% of TCs) in comparison with classical PTC and TCVPTC (PTC with more than 50% of TCs) to clarify the controversial issue. Four electronic databases including PubMed, Web of Science, Scopus and Virtual Health Library were accessed to search for relevant articles. We extracted data from published studies and pooled into odds ratio (OR) and its corresponding 95% confidence intervals (CIs) using random-effect modeling. Nine studies comprising 403 TCVPTCs, 325 PTC-TCFs and 3552 classical PTCs were included for meta-analyses. Overall, the clinicopathological profiles of PTC-TCF including multifocality, extrathyroidal extension, lymph node metastasis, distant metastasis and patient mortality were not statistically different from those of TCVPTC. Additionally, PTC-TCF and TCVPTC were both associated with an increased risk for aggressive clinical courses as compared to classical PTC. The prevalence of BRAF mutation in PTC-TCF and TCVPTC was comparable and both were significantly higher than that in classical PTC. The present meta-analysis demonstrated that even a PTC comprising only 10% of TCs might be associated with a poor clinical outcome. Therefore, the proportions of PTC in PTC should be carefully estimated and reported even when the TC component is as little as 10%.

A comparison of the clinicopathological features and prognoses of the classical and the tall cell variant of papillary thyroid cancer: a meta-analysis

Papillary thyroid cancer (PTC) accounts for 80–90% of all thyroid malignancies. The tall cell variant (TCV) is a rare aggressive histotype of PTC. We performed a meta-analysis to compare the clinicopathological characteristics and prognostic factors of TCV with those of classical papillary thyroid carcinoma (cPTC). A literature search was performed using the PubMed and EMBASE databases using Medical Subject Headings and keywords. Twenty studies that included 1871 patients with TCV and 75323 patients with cPTC were included in our meta-analysis. Odds ratios and confidence intervals were calculated for each study. Patients with TCV were associated with multifocality, higher TNM stage, extrathyroidal extension, vascular invasion, lymph node metastasis, distant metastasis, BRAF mutation, disease-specific survival, and overall survival. We found that TCV cases were associated with more aggressive clinicopathological characteristics and poorer prognoses than cPTC cases were. Our results suggest that TCV is a high-risk PTC that warrants aggressive treatment and follow-up strategies.

Tall cell variant of papillary thyroid carcinoma: current evidence on clinicopathologic features and molecular biology

Tall cell variant (TCV) of papillary thyroid carcinoma (PTC) has been recognized for the past few decades as an entity showing aggressive biological behavior; however, there is considerable controversy regarding the definition, clinical and pathological features of TCV because of its rarity and difficult diagnosis. No clinical features can accurately diagnose TCV. Thus, the results of histocytology, immunohistochemistry and molecular genetics tests have important clinical implications for diagnosis. Given the aggressiveness and the increased recurrence and poor survival rates, more aggressive treatment approach and rigorous follow-up is required for patients with TCV. In the present article, we undertook a comprehensive review to summarize and discuss the various aspects of this variant, from morphology to immunohistochemistry, and molecular abnormalities from a practical and daily practice-oriented point of view.

[BRAF-positive paucicellular variant of anaplastic carcinoma in the presence of tall cell variant papillary thyroid cancer]

To paper describes a case of paucicellular anaplastic cancer in the presence of tall cell variant papillary thyroid carcinoma. Microscopic examination showed that the differentiated component of the tumor was composed of papillary structures with tall cells, the height of which exceeded 3-4 times the width. Its anaplastic component consisted of fibrous tissue with occasional spindle-shaped cells and focal lymphocytic infiltration to the extent of 70%. The spindle-shaped cells expressed cytokeratins, β-catenin, p53, and vimentin. The tumor cells and lymphocytes showed an association with Epstein-Barr virus. Molecular genetic study of the tumor revealed the following mutations: BRAF p.Val600Glu (p.V600e was), HRAS p.His27His (p.H27H), PIK3CA p.Glu545Lys (p.E545K), TP53 p.Arg248Gln (p.R248Q).

Molecular correlates and rate of lymph node metastasis of non-invasive follicular thyroid neoplasm with papillary-like nuclear features and invasive follicular variant papillary thyroid carcinoma: the impact of rigid criteria to distinguish non-invasive follicular thyroid neoplasm with papillary-like nuclear features

Thyroid tumors formerly classified as non-invasive encapsulated follicular variant of papillary thyroid carcinoma were recently renamed 'non-invasive follicular thyroid neoplasm with papillary-like nuclear features'. The current study investigated the frequency of lymph node metastasis and mutational profile of encapsulated follicular variant in the setting of a clinical practice where central neck dissection was the standard of practice. We defined the impact of rigid diagnostic criteria by regrouping such tumors based on the complete absence of papillae or presence of ≤1% papillae. Of a total of 6,269 papillary thyroid carcinomas, 152 tumors fulfilled the criteria for encapsulated follicular variant. The results were stratified according to two different diagnostic cutoff criteria with respect to the extent of papillae. When the cutoff of 1% papillae was used, the rates of lymph node metastasis and BRAF^V600E mutation were 3% and 10% in non-invasive tumors and 9% and 4% in invasive tumors, respectively. Despite the lack of invasive growth, one patient with BRAF^V600E mutant-tumor displaying predominant follicular growth and subtle papillae developed a bone metastasis. When absence of papillary structure was applied as rigid diagnostic criteria, no BRAF^V600E mutation was found in all tumors. However, central lymph node micrometastasis still occurred in 3% of non-invasive tumors. Non-V600E BRAF and RAS mutations were detected in 4% and 47% of non-invasive tumors, respectively. Our findings suggest that non-invasive follicular thyroid neoplasm with papillary-like nuclear features should not be regarded as a benign thyroid neoplasm as it can present with lymph node micrometastasis and should not be diagnosed in the presence of even a single papillary structure. Our findings underscore the original American Thyroid Association recommendation that defined non-invasive encapsulated follicular variants as low risk thyroid cancers. Clinical surveillance similar to low risk differentiated thyroid cancers and capture of this diagnostic category by Cancer Registries should be considered.

Update on the cytologic features of papillary thyroid carcinoma variants

Papillary thyroid cancer (PTC), which accounts for 85-90% of all thyroid cancers, is generally an indolent tumor with long term survival rates >95%. A reliable definitive diagnosis of PTC is usually straightforward in fine needle aspirates of conventional PTC whenever the characteristic papillary and/or flat honeycomb sheet-like architecture and the typical nuclear features of chromatin pallor, nuclear enlargement, crowding, grooves and pseudoinclusions are encountered. Conventional PTC, however, has diminished in relative frequency as compared to PTC variants, especially the noninvasive follicular variant of PTC, an indolent tumor which has recently been reclassified as "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP). These PTC variants are characterized by various architecture, cell type and shape, and stromal features, some of which can be recognized cytologically. Awareness of the cytomorphological spectrum and of the characteristic cytological features of these PTC variants is important to avoid diagnostic pitfalls. In this article, we review the different variants of PTC, including their cytomorphologic features, differential diagnosis, and salient molecular features. Diagn. Cytopathol. 2017;45:714-730. © 2017 Wiley Periodicals, Inc.

TERT Promoter Mutation in an Aggressive Cribriform Morular Variant of Papillary Thyroid Carcinoma

The cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC) is a rare thyroid neoplasm characterized by unique morphologic findings and association with familial adenomatous polyposis. The biologic behavior of this variant has been reported to behave similarly to classic PTC. We report a rare sporadic case of CMV-PTC occurring in a 45-year-old female with multiple lymph nodes and bone metastases, which were detected after total thyroidectomy and radioactive iodine remnant ablation. Molecular analyses of primary thyroid and metastatic tumor tissues revealed a telomerase reverse transcriptase (TERT) promoter mutation, but absence of BRAF, KRAS, NRAS, HRAS, and PIK3CA mutations. Over a 4-year follow-up period, structurally identifiable bone metastases were persistent, but serial post-operative serum thyroglobulin levels remained undetectable in the absence of thyroglobulin antibody. The literature was reviewed. This is the first case of aggressive CMV-PTC showing TERT promoter mutation. TERT promoter mutations may help in predicting aggressive clinical behavior in CMV-PTC. Postoperative serum thyroglobulin measurement may have no impact on clinical decision-making in this type of tumor.

Clinical utility of TERT promoter mutations and ALK rearrangement in thyroid cancer patients with a high prevalence of the BRAF V600E mutation

Background

Mutations in the TERT promoter, ALK rearrangement, and the BRAF V600E mutation are associated with aggressive clinicopathologic features in thyroid cancers. However, little is known about the impact of TERT promoter mutations and ALK rearrangement in thyroid cancer patients with a high prevalence of BRAF mutations.

Methods

We performed Sanger sequencing to detect BRAF V600E and TERT promoter mutations and both immunohistochemistry and fluorescence in situ hybridization to identify ALK rearrangement on 243 thyroid cancers.

Results

TERT promoter mutations were not present in 192 well-differentiated thyroid carcinomas (WDTC) without distant metastasis or in 9 medullary carcinomas. However, the mutations did occur in 40 % (12/30) of WDTC with distant metastasis, 29 % (2/7) of poorly differentiated carcinomas and 60 % (3/5) of anaplastic carcinomas. ALK rearrangement was not present in all thyroid cancers. The BRAF V600E mutation was more frequently found in WDTC without distant metastasis than in WDTC with distant metastasis (p = 0.007). In the cohort of WDTC with distant metastasis, patients with wild-type BRAF and TERT promoter had a significantly higher response rate after radioiodine therapy (p = 0.024), whereas the BRAF V600E mutation was significantly correlated with progressive disease (p = 0.025).

Conclusions

The TERT promoter mutation is an independent predictor for distant metastasis of WDTC, but ALK testing is not useful for clinical decision-making in Korean patients with a high prevalence of the BRAF V600E mutation. Radioiodine therapy for distant metastasis of WDTC is most effective in patients without BRAF V600E and TERT promoter mutations.

BRAF Immunohistochemistry Using Clone VE1 is Strongly Concordant with BRAF(V600E) Mutation Test in Papillary Thyroid Carcinoma

The aim of this study was to investigate the concordance between BRAF(V600E) mutation test and immunohistochemistry (IHC) and determine the diagnostic accuracy of IHC for papillary thyroid carcinoma (PTC) through a systematic review, meta-analysis, and diagnostic test accuracy review. The current systematic review and meta-analysis included 1141 PTCs in 11 eligible studies. We investigated the concordance rate and performed subgroup analysis using tissue and cytologic samples. Diagnostic test accuracy review was conducted and calculated using the value of area under curve (AUC) on the summary receiver operating characteristic (SROC) curve. The positive rate of BRAF IHC was 79.1% (903 of 1141 cases), and the BRAF(V600E) mutation was found in 76.6% (874 of 1141 cases). The concordance rates were 0.921 (95% confidence interval (CI) 0.877-0.950) and 0.894 (95% CI 0.801-0.946) in IHC positive and negative subgroups, respectively. In the diagnostic test accuracy review, the pooled sensitivity and specificity were 0.97 (95% CI 0.95-0.98) and 0.78 (95% CI 0.72-0.83). The value of AUC on SROC curve was 0.983, and diagnostic odds ratio was 164.28 (95% CI 57.69-467.80). Our results showed that BRAF IHC was strongly concordant with BRAF mutation test and had high diagnostic accuracy in BRAF mutation analysis of PTC.

Cytologic, clinicopathologic, and molecular features of papillary thyroid carcinoma with prominent hobnail features: 10 case reports and systematic literature review

The hobnail variant of papillary thyroid carcinoma (PTC) is a rare, aggressive variant in which > 30% of the tumor cells have hobnail features. The clinical behavior and pathologic characteristics of these tumors are still unclear due to the rarity of the entity. The present study aimed to investigate cytologic, clinical, pathological, and molecular features of the hobnail variant from our data and from the literature. We retrospectively retrieved 10 cases of hobnail variant from 2,904 consecutive PTC patients. Cytologic and histopathologic slides from those 10 patients were reviewed. We performed molecular analysis for BRAF, ALK, and TERT promoter mutations on paraffin blocks from surgical specimens, and further analyzed the clinicopathologic characteristics of all case reports published in the literature until now. Cytologically, all tumors were characterized by single cells with eccentric nuclei and tapering cytoplasm (comet-like cells), and syncytial or micropapillary clusters with apically placed nuclei resulting in a hobnail appearance in both conventional smears and liquid-based cytology. The BRAF V600E mutation was found in 8 cases (80%) whereas no cases had ALK fusion or TERT promoter mutations. In the literature review of 55 patients including our cases, most patients presented with advanced stage cancer, and disease-specific survival rates were 83%, 71%, and 54% at 5, 10, and 20 years after the initial surgery, respectively. Characteristic cytologic features can allow a preoperative diagnosis of the hobnail variant of PTC based on cytology specimens. Further studies should be performed to identify the molecular genetics of the variant.

The Warthin-Like Variant of Papillary Thyroid Carcinoma: A Comparison with Classic Type in the Patients with Coexisting Hashimoto's Thyroiditis

Background. The Warthin-like variant of papillary thyroid (WLPTC) is a rare subtype of papillary thyroid carcinoma (PTC) resembling Warthin tumors of the salivary glands. Due to its rarity, the clinicopathologic and molecular features of WLPTC remain unclear. Methods. Of the 2,139 patients who underwent surgical treatment for PTC from 2012 to 2013, 40 patients with WLPTC were identified and compared to 200 consecutive patients with classic PTC. BRAF mutation was tested with pyrosequencing. Results. There were no significant differences in age, predilection for women, multifocality, extrathyroidal extension, or lymph node metastasis between WLPTC and classic PTC. However, WLPTCs were more commonly associated with Hashimoto's thyroiditis than classic PTCs (93% versus 36%, resp., P < 0.001) and showed significantly lower rate of BRAF mutation when compared to classic PTCs (65% versus 84%, resp., P = 0.007). In classic PTC, the frequency of BRAF mutations was negatively correlated with coexisting Hashimoto's thyroiditis. When we compared WLPTC and classic PTC in the patients with coexisting Hashimoto's thyroiditis, there were no significant differences in clinicopathologic characteristics or the BRAF mutational rate between the two groups. Conclusions. Patients with WLPTC have similar demographic, clinical, pathologic, and molecular characteristics to those with classic PTC coexisting with Hashimoto's thyroiditis.