A Systematic Review and Meta-Analysis of the Diagnostic Performance of BRAF V600E Immunohistochemistry in Thyroid Histopathology

Initial Management of BRAF V600E-Variant Anaplastic Thyroid Cancer: The FAST Multidisciplinary Group Consensus Statement

Importance

BRAF/MEK inhibitors revolutionized the treatment of BRAF V600E-variant anaplastic thyroid carcinoma (BRAFv-ATC), offering improved outcomes for patients with this previously incurable disease.

Observations

Anaplastic thyroid carcinoma (ATC) accounts for approximately half of thyroid cancer-related deaths. It presents as a rapidly growing tumor that often invades locoregional structures and spreads to distant sites early; therefore, prompt diagnosis, staging, and treatment initiation are of the essence in the treatment of ATC. Although most oncologists will encounter a patient with ATC in their practice, the rarity of this disease makes treatment challenging, particularly because those with BRAFv-ATC no longer have a dismal prognosis. BRAF/MEK kinase inhibitors have transformed the outlook and treatment of BRAFv-ATC. Therefore, molecular profiling to identify these patients is critical. More recently, the addition of immunotherapy to BRAF/MEK inhibitors as well as the use of the neoadjuvant approach were shown to further improve survival outcomes in BRAFv-ATC. Many of these recent advances have not yet been incorporated in the currently available guidelines, allowing for disparities in the treatment of patients with BRAFv-ATC across the US. With the increasing complexity in the management of BRAFv-ATC, this Consensus Statement aims to formulate guiding recommendations from a group of experts to facilitate therapeutic decision-making.

Conclusions and Relevance

This Consensus Statement from the FAST (Facilitating Anaplastic Thyroid Cancer Specialized Treatment) group at MD Anderson Cancer Center emphasizes that rapid identification of a BRAF V600E pathogenic variant and timely initiation of sequential therapy are critical to avoid excess morbidity and mortality in patients with BRAFv-ATC. In the past decade, remarkable progress has been made in the treatment of patients with BRAFv-ATC, justifying these new evidence-based recommendations reached through a consensus of experts from a high-volume center.

Effective detection of BRAFV595E mutation in canine urothelial and prostate carcinomas using immunohistochemistry

Canine urothelial carcinoma (UC) and prostate carcinoma (PC) frequently exhibit the BRAFV595E mutation, akin to the BRAFV600E mutation common in various human cancers. Since the initial discovery of the BRAF mutation in canine cancers in 2015, PCR has been the standard method for its detection in both liquid and tissue biopsies. Considering the similarity between the canine BRAFV595E and human BRAFV600E mutations, we hypothesized that immunohistochemistry (IHC) using a BRAFV600E-specific antibody could effectively identify the canine mutant BRAFV595E protein. We tested 122 canine UC (bladder n = 108, urethra n = 14), 21 PC, and benign tissue using IHC and performed digital droplet PCR (ddPCR) on all 122 UC and on 14 IHC positive PC cases. The results from ddPCR and IHC were concordant in 99% (135/136) of the tumours. Using IHC, BRAFV595E was detected in 72/122 (59%) UC and 14/21 (65%) PC. Staining of all benign bladder and prostate tissues was negative. If present, mutant BRAF staining was homogenous, with rare intratumour heterogeneity in three (4%) cases of UC. Additionally, the BRAFV595E mutation was more prevalent in tumours with urothelial morphology, and less common in glandular PC or UC with divergent differentiation. This study establishes that BRAFV600-specific IHC is a reliable and accurate method for detecting the mutant BRAFV595E protein in canine UC and PC. Moreover, the use of IHC, especially with tissue microarrays, provides a cost-efficient test for large-scale screening of canine cancers for the presence of BRAF mutations. This advancement paves the way for further research to define the prognostic and predictive role of this tumour marker in dogs and use IHC to stratify dogs for the treatment with BRAF inhibitors.

Are there specific cytologic features that can predict BRAFV600E mutational status of papillary thyroid carcinoma in fine-needle aspiration specimens?

BACKGROUND

BRAFV600E mutation is the most common molecular alteration found in papillary thyroid carcinoma (PTC) and has been linked to recurrent disease or possibly more aggressive behavior. Some studies have reported sickle-shaped nuclei (SSN) and plump pink cells (PPC) to be predictive markers of BRAF mutation in FNA cytology. We aimed to evaluate the reproducibility of the aforementioned cytologic features.

METHODS

A computerized search for diagnosed PTC surgical pathology cases tested for BRAFV600E mutation by Sanger DNA sequencing was performed. Blinded to BRAF results, the corresponding cytology was reviewed for presence of SSN and PPC. Classic nuclear PTC (CNPTC) features, cystic change, and psammoma bodies were also evaluated. The results were correlated with BRAFV600E mutational status and histologic subtypes.

RESULTS

Study cohort consisted of 113 cases (74 BRAFV600E mutated, 39 BRAFV600E wild type). SSN and combined CNPTC /SSN had positive predictive value of 74% and 75%, respectively. CNPTC showed 92% sensitivity and 20% specificity. Psammoma bodies had 92% specificity and 5% sensitivity. The presence of combined PPC/SSN showed 80% specificity, 27% sensitivity, and diagnostic accuracy of 45%. CNPTC was seen in 60/61 (98%) SSN and 45/45 (100%) PPC. There was no significant statistical association between SSN, PPC, and CNPTC with specific histologic subtypes and BRAF mutational status.

CONCLUSION

CNPTC is sensitive but not specific for BRAF mutational status. SSN, PPC, and CNPTC are not predictive markers for the presence of BRAF mutation or histologic subtypes. Additional studies may be needed to further corroborate these findings.

Divergent Lineage Markers in Anaplastic Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) often results from dedifferentiation of differentiated thyroid carcinoma (DTC), and the diagnosis is not difficult, as the tumor is seen to progress from a recognized DTC. However, in some cases, the diagnosis based on biopsy of limited tissue or resection of a completely undifferentiated tumor relies on immunohistochemical biomarkers and is usually a diagnosis of exclusion. To examine the biomarker profile of ATC and to determine whether divergent lineage markers can complicate this process, we examined the expression of a number of biomarkers in a series of ATCs. Cases retrieved from the department laboratory information system were included if there was evidence of an accurate diagnosis based on the presence of a coexisting or antecedent DTC or in cases where the immunoprofile was consistent with thyroid origin in a non-equivocal clinical setting. Questionable cases were excluded. We identified 36 cases for analysis. Tissue sections were stained for PAX8, TTF1, BRAFV600E, NRASQ61R, TRK, and p53, as well as p40, CDX2, SATB2, GATA3, CD117, CD163, SALL4, SMARCA4, PRAME, SOX10, ERG and HEPPAR1. As expected, all 36 ATCs were negative for TTF1 except for one showing focal, weak expression. Thirteen expressed PAX8 with variable intensity. BRAFV600E was positive in 10/34 tumors and equivocal in 3; NRASQ61R was positive in 12, and TRK was positive in 1 case. Staining for p53 was diffusely positive in 14 and completely negative in 19, with only 3 cases showing a wild-type pattern. We found aberrant expression of GATA3 in 11/36 cases, SATB2 in 8/36, CD117 in 2/35, and SALL4 in 1/30. CD163 expression was identified in tumor cells in 10/30 cases with variable intensity; in the other tumors, interpretation was obscured by abundant histiocytes. P40 was positive in 5 cases with squamoid morphology. CDX2 was negative in 35 tested cases. PRAME was identified in 1 of 33 cases. Stains for SOX10, ERG, and HEPPAR1 were negative in 33 cases. Twenty tested cases showed retained SMARCA4 expression. We conclude that ATCs express a number of divergent lineage markers that can cause diagnostic dilemmas, as they are also features of other tumors in the differential diagnosis of high-grade midline neck malignancies.

Annotation-Free Deep Learning-Based Prediction of Thyroid Molecular Cancer Biomarker BRAF (V600E) from Cytological Slides

Thyroid cancer is the most common endocrine cancer. Papillary thyroid cancer (PTC) is the most prevalent form of malignancy among all thyroid cancers arising from follicular cells. Fine needle aspiration cytology (FNAC) is a non-invasive method regarded as the most cost-effective and accurate diagnostic method of choice in diagnosing PTC. Identification of BRAF (V600E) mutation in thyroid neoplasia may be beneficial because it is specific for malignancy, implies a worse prognosis, and is the target for selective BRAF inhibitors. To the authors' best knowledge, this is the first automated precision oncology framework effectively predict BRAF (V600E) immunostaining result in thyroidectomy specimen directly from Papanicolaou-stained thyroid fine-needle aspiration cytology and ThinPrep cytological slides, which is helpful for novel targeted therapies and prognosis prediction. The proposed deep learning (DL) framework is evaluated on a dataset of 118 whole slide images. The results show that the proposed DL-based technique achieves an accuracy of 87%, a precision of 94%, a sensitivity of 91%, a specificity of 71% and a mean of sensitivity and specificity at 81% and outperformed three state-of-the-art deep learning approaches. This study demonstrates the feasibility of DL-based prediction of critical molecular features in cytological slides, which not only aid in accurate diagnosis but also provide useful information in guiding clinical decision-making in patients with thyroid cancer. With the accumulation of data and the continuous advancement of technology, the performance of DL systems is expected to be improved in the near future. Therefore, we expect that DL can provide a cost-effective and time-effective alternative tool for patients in the era of precision oncology.

The diagnostic utility of BRAF VE1 mutation-specific immunohistochemistry in ameloblastoma

Ameloblastoma is a benign, locally aggressive odontogenic neoplasm with variable solid and cystic morphology. On account of its histologic variety, diagnostically challenging cases can bear resemblance to odontogenic keratocyst/keratocystic odontogenic tumor (KCOT) or dentigerous cyst (DC). BRAF^V600E mutation has been reported to be specific for and frequent in ameloblastoma, and this study evaluated the usefulness of immunohistochemistry (IHC) using the BRAF VE1 mutant-specific antibody as a diagnostic adjunct in this setting. We investigated 46 ameloblastomas, 30 KCOTs, and 30 DCs. BRAF VE1 IHC was performed on all cases and allele-specific polymerase chain reaction (AS-PCR) for BRAF^V600E mutation was performed on 30 ameloblastomas and any IHC-positive KCOT/DC. BRAF VE1 IHC was positive in 31/37 (83.8%) mandibular ameloblastomas but not in any maxillary ameloblastomas (0/9), KCOT (0/30), or DC (0/30). Equivocal staining was seen in 1/37 (3.3%) mandibular ameloblastomas. Of the 30 ameloblastomas subjected to AS-PCR, BRAF^V600E mutation was identified in 19/23 (82.6%) mandibular ameloblastomas and 0/7 (0.0%) maxillary ameloblastomas. BRAF^V600E mutant ameloblastomas were positive by IHC in 18/19 (94.7%) cases and equivocal in 1/19 (5.3%) cases. All 11 (100.0%) BRAF-wild type ameloblastomas were negative by IHC. BRAF VE1 is an excellent tool for the diagnosis of mandibular ameloblastoma but of limited utility in the maxilla, where it less commonly occurs and where BRAF^V600E mutation is considerably less frequent.

Overview of the 2022 WHO Classification of Thyroid Neoplasms

This review summarizes the changes in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors that relate to the thyroid gland. The new classification has divided thyroid tumors into several new categories that allow for a clearer understanding of the cell of origin, pathologic features (cytopathology and histopathology), molecular classification, and biological behavior. Follicular cell-derived tumors constitute the majority of thyroid neoplasms. In this new classification, they are divided into benign, low-risk, and malignant neoplasms. Benign tumors include not only follicular adenoma but also variants of adenoma that are of diagnostic and clinical significance, including the ones with papillary architecture, which are often hyperfunctional and oncocytic adenomas. For the first time, there is a detailed account of the multifocal hyperplastic/neoplastic lesions that commonly occur in the clinical setting of multinodular goiter; the term thyroid follicular nodular disease (FND) achieved consensus as the best to describe this enigmatic entity. Low-risk follicular cell-derived neoplasms include non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), thyroid tumors of uncertain malignant potential, and hyalinizing trabecular tumor. Malignant follicular cell-derived neoplasms are stratified based on molecular profiles and aggressiveness. Papillary thyroid carcinomas (PTCs), with many morphological subtypes, represent the BRAF-like malignancies, whereas invasive encapsulated follicular variant PTC and follicular thyroid carcinoma represent the RAS-like malignancies. This new classification requires detailed subtyping of papillary microcarcinomas similar to their counterparts that exceed 1.0 cm and recommends not designating them as a subtype of PTC. The criteria of the tall cell subtype of PTC have been revisited. Cribriform-morular thyroid carcinoma is no longer classified as a subtype of PTC. The term "Hürthle cell" is discouraged, since it is a misnomer. Oncocytic carcinoma is discussed as a distinct entity with the clear recognition that it refers to oncocytic follicular cell-derived neoplasms (composed of > 75% oncocytic cells) that lack characteristic nuclear features of PTC (those would be oncocytic PTCs) and high-grade features (necrosis and ≥ 5 mitoses per 2 mm²). High-grade follicular cell-derived malignancies now include both the traditional poorly differentiated carcinoma as well as high-grade differentiated thyroid carcinomas, since both are characterized by increased mitotic activity and tumor necrosis without anaplastic histology and clinically behave in a similar manner. Anaplastic thyroid carcinoma remains the most undifferentiated form; squamous cell carcinoma of the thyroid is now considered as a subtype of anaplastic carcinoma. Medullary thyroid carcinomas derived from thyroid C cells retain their distinct section, and there is a separate section for mixed tumors composed of both C cells and any follicular cell-derived malignancy. A grading system for medullary thyroid carcinomas is also introduced based on mitotic count, tumor necrosis, and Ki67 labeling index. A number of unusual neoplasms that occur in the thyroid have been placed into new sections based on their cytogenesis. Mucoepidermoid carcinoma and secretory carcinoma of the salivary gland type are now included in one section classified as "salivary gland-type carcinomas of the thyroid." Thymomas, thymic carcinomas and spindle epithelial tumor with thymus-like elements are classified as "thymic tumors within the thyroid." There remain several tumors whose cell lineage is unclear, and they are listed as such; these include sclerosing mucoepidermoid carcinoma with eosinophilia and cribriform-morular thyroid carcinoma. Another important addition is thyroblastoma, an unusual embryonal tumor associated with DICER1 mutations. As in all the WHO books in the 5th edition, mesenchymal and stromal tumors, hematolymphoid neoplasms, germ cell tumors, and metastatic malignancies are discussed separately. The current classification also emphasizes the value of biomarkers that may aid diagnosis and provide prognostic information.

Diagnostic Value of Bronchoscopy for Peripheral Metastatic Lung Tumors

Simple Summary

Metastatic lung tumors are relatively common, and their pathological diagnosis is crucial for determining the appropriate treatment strategy. Although bronchoscopy is one biopsy method, its role has not been established for peripheral metastatic lung tumors. The present study aimed to investigate the value of bronchoscopy, using radial endobronchial ultrasound for diagnosis. We analyzed 235 lesions consecutively, and the overall diagnostic yield was 76.6%, which was slightly higher than the reported cumulative sensitivity for general peripheral pulmonary lesions. There were no serious complications. The results demonstrated that bronchoscopy is a valuable technique for peripheral metastatic lung tumors that combines diagnostic accuracy and safety. Moreover, the higher diagnostic yield was associated with the large lesion size, inner location, and visibility on radiography. These findings should contribute to the selection of biopsy methods for metastatic lung tumors and improve the diagnostic yield.

Abstract

Although lungs are one of the most frequent sites of metastasis for malignant tumors, little has been reported about the value of bronchoscopy for lung metastases presenting with peripheral pulmonary lesions (PPLs). This retrospective cohort study investigated the diagnostic value of bronchoscopy for peripheral metastatic lung tumors. Consecutive patients who underwent diagnostic bronchoscopy with radial endobronchial ultrasound for PPLs and were finally diagnosed with metastatic lung tumors from April 2012 to March 2019 were included. We analyzed 235 PPLs, with a median size of 18.8 mm. The overall diagnostic yield was 76.6%. In a multivariable analysis, large lesion size (>20.0 mm vs. <20.0 mm: 87.6% vs. 67.7%, p = 0.043, OR = 2.26), inner location (inner 2/3 vs. outer 1/3: 84.8% vs. 69.1%, p = 0.004, OR = 2.79), and visibility on radiography (visible vs. invisible: 83.2% vs. 56.1%, p = 0.015, OR = 3.29) significantly affected the diagnostic yield. Although a positive bronchus sign tended to have a higher yield, no significant difference was observed (81.8% vs. 70.6%, p = 0.063). Only one case of lung abscess was observed, with no serious complications. In conclusion, bronchoscopy is a valuable technique for peripheral metastatic lung tumors, with good diagnostic accuracy and safety.

Application of Immunohistochemistry in Papillary Thyroid Carcinoma

Immunohistochemistry (IHC) is an economic and precise method to localize the presence of specific protein at cellular level in tissue. Although many papillary thyroid carcinomas do not require IHC to render a diagnosis, there are certain scenarios in which IHC are important. The major diagnostic applications of IHC include confirmation of papillary thyroid carcinoma in sites other than the thyroid, distinguish papillary thyroid carcinoma from other primary thyroid neoplasms in thyroid, and identify papillary thyroid carcinoma from secondary tumors to the thyroid. At research level, IHC could help identify prognostic information, identify underlying genetic alterations, and predict response to treatment in papillary thyroid carcinoma. The understanding of principle and recent advances in IHC will improve the diagnosis and management of patients with thyroid lesions including papillary thyroid carcinoma.

Emerging Biomarkers in Thyroid Practice and Research

Simple Summary

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

Abstract

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

A prediction model incorporating the BRAFV600E protein status for determining the risk of cervical lateral lymph node metastasis in papillary thyroid cancer patients with central lymph node metastasis

BACKGROUND AND OBJECTIVES

Cervical lateral lymph node metastasis (LLNM) is a predictor of poor prognosis for papillary thyroid carcinoma (PTC) patients. However, the risk factors for LLNM remain unclear. The purpose of the study was to examine the risk factors for LLNM and construct a prediction model.

METHODS

With Ethics Committee approval, a total of 1198 PTC patients were retrospectively included in our study. Univariate and multivariate analyses were performed to explore the relationship between clinicopathological characteristics and LLNM. A nomogram for predicting LLNM in PTC patients with central lymph node metastasis (CLNM) was constructed and validated.

RESULTS

The negative BRAF^V600E protein expression was significantly correlated with positive LLNM status in PTC patients. In PTC patients with CLNM, the number of metastatic central lymph nodes (LNN) ≥ 3 and the ratio of metastatic central lymph nodes (LNR) ≥ 0.565 were found to be significantly associated with positive LLNM status. The nomogram for predicting LLNM risk in PTC patients with CLNM incorporated four risk factors: tumor size, the BRAF^V600E protein expression, LNN and LNR. The prediction model showed excellent discrimination, with a C-index of 0.714.

CONCLUSIONS

The negative BRAF^V600E protein expression was more likely to lead to LLNM. LNN ≥3 and LNR ≥0.565 were associated with LLNM risk in PTC patients with CLNM. Our nomogram might assist clinicians in developing individual suitable follow-up strategies for PTC patients with CLNM.

Capsular Invasion Matters Also in "Papillary Patterned" Tumors: A Study on 121 Cases of Encapsulated Conventional Variant of Papillary Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy. Some PTCs with classical papillae can be totally or partially encapsulated, and these tumors are called "encapsulated" (conventional) variant of papillary thyroid carcinoma. We aimed to investigate the clinicopathological features of this variant, comparing with non-encapsulated conventional type PTC. Among 823 thyroidectomy specimens with PTC diagnosed between 2015 and 2018, 121 tumors from 105 patients (12.75%) were reclassified as encapsulated conventional PTC. In 76 patients, tumors were unifocal. Size, cystic changes, background thyroiditis, psammoma bodies, cervical lymph node metastasis at presentation, capsular/vascular invasion, and immunohistochemical BRAF-V600E expression were evaluated. Ninety-two non-encapsulated conventional PTCs served as control group. Encapsulated cases were predominantly women (73.3%), 56.4% were microcarcinomas, 97.5% had cystic changes, 81.4% were BRAF-V600E positive, and 36.8% of unifocal encapsulated tumors had cervical lymph node metastasis. Thyroiditis and psammoma bodies were detected in nearly half of the encapsulated PTCs. Fourteen percent of the unifocal tumors showed total encapsulation, whereas capsular and vascular invasion was detected in 85.5% and 5.8%, respectively. Encapsulated cases did not show any significant difference from the control group, except for prominent cystic changes (p < 0.001). Relationship between lymph node metastasis at presentation and capsular invasion was statistically significant (p = 0.001), and metastasis was more frequent in cases with extensive capsular invasion (no/minimal invasion versus extensive invasion, p < 0.001). Cystic changes are very common, and this feature deserves mentioning as a morphological characteristic of encapsulated conventional PTCs. As in encapsulated "follicular" variant of PTC, capsular invasion status is important in evaluating papillary patterned encapsulated PTC for predicting lymph node metastasis. Total examination of the tumor capsule and inclusion of capsular invasion status in pathology reports are recommended.

Weakly supervised learning on unannotated hematoxylin and eosin stained slides predicts BRAF mutation in thyroid cancer with high accuracy

Deep neural networks (DNNs) that predict mutational status from H&E slides of cancers can enable inexpensive and timely precision oncology. Although expert knowledge is reliable for annotating regions informative of malignancy and other known histological patterns (strong supervision), it is unreliable for identifying regions informative of mutational status. This poses a serious impediment to obtaining higher prognostic accuracy and discovering new knowledge of pathobiology. We used a weakly supervised learning technique to train a DNN to predict BRAF V600E mutational status, determined using DNA testing, in H&E stained images of thyroid cancer tissue without regional annotations. Our discovery cohort was a tissue microarray of only 85 patients from a single hospital. Yet, on a large independent external cohort of 444 patients from other hospitals, the trained model gave an AUC = 0.98 (95% CI: 0.97-1.00), which is much higher than the previously reported results for detecting any mutation using H&E by DNNs trained using strong supervision. We also developed a visualization technique that can automatically highlight regions the DNN found most informative for predicting mutational status. Our visualization is spatially granular and highly specific in highlighting regions with strong negative and positive regions and move us towards explainable artificial intelligence. Using t-tests, we confirmed that the proportions of follicular or papillary histology and oncocytic cytology, as noted for each patient by a pathologist who was blinded to the mutational status, were significantly different between mutated and wildtype patients. However, based solely on these features noted by the pathologist, a logistic regression classifier gave an average AUC = 0.78 in 5-fold CV, which is much lower than that obtained using the DNN. These results highlight the potential of weakly supervised learning for training DNN models for problems where the informative visual patterns and their locations are not known a priori. This article is protected by copyright. All rights reserved.

Oestrogen receptor alpha in papillary thyroid carcinoma: association with clinical features and BRAFV600E mutation

BACKGROUND

Papillary thyroid cancer cells can express oestrogen receptor alpha, which is encoded by the ESR1 gene and may bind to oestrogen to induce the occurrence and development of papillary thyroid cancer. The BRAFV600E mutation is also an important biomarker for the occurrence and progression of papillary thyroid cancer. However, the association between the BRAFV600E mutation and oestrogen receptor alpha expression has not been identified. This study aims to investigate the association between ESR1 expression and the BRAFV600E mutation and its clinical significance.

METHODS

Oestrogen receptor alpha and BRAFV600E proteins were detected by immunohistochemical staining of formalin-fixed paraffin-embedded thyroid tissues from 1105 patients with papillary thyroid cancer at our institution. Messenger RNA expression counts of ESR1 and clinicopathologic information were obtained from The Cancer Genome Atlas database.

RESULTS

Oestrogen receptor alpha protein expression was significantly associated with BRAFV600E protein. The positive rate of oestrogen receptor alpha protein in papillary thyroid cancer patients was significantly higher in males, younger patients and patients with the multifocal type. In papillary thyroid cancer patients with positive BRAFV600E protein, oestrogen receptor alpha expression was significantly correlated with central lymph node metastasis. Data from the The Cancer Genome Atlas database also suggested that the ESR1 messenger RNA level was associated with the BRAFV600E mutation. Furthermore, classification analysis performed according to a tree-based classification method demonstrated that higher ESR1 messenger RNA expression indicated poorer overall survival in papillary thyroid cancer patients with the BRAFV600E mutation.

CONCLUSIONS

The percentage of BRAFV600E mutations is increased in patients with higher ESR1 messenger RNA levels, and the BRAFV600E protein might be co-expressed with oestrogen receptor alpha, which could be an indicator of cervical lymph node metastasis and poor overall survival in patients with papillary thyroid cancer.

Clinical significance of immunohistochemistry to detect BRAF V600E mutant protein in thyroid tissues

This study investigated the feasibility of using immunohistochemistry (IHC) instead of PCR to detect BRAF V600E mutant protein in papillary thyroid carcinoma (PTC), and to determine the value of using preoperative BRAF V600E mutant protein by IHC to assist in the diagnosis of thyroid nodule patients with Hashimoto's thyroiditis (HT).The expression of BRAFV600E mutant protein was measured in 23 cases of HT+PTC, 31 cases of PTC, and 28 cases of HT by IHC, followed by PCR in the same samples for validation. SPSS 19.0 software was used for statistical analysis.The sensitivity and specificity of IHC to detect BRAF V600E mutation were 100% and 42.86%, respectively. In addition, the mutation rate of BRAF V600E protein in the HT+PTC group (34.78%, 8/23) was lower than that in the PTC group (80.65%, 25/31).The application of IHC to detect BRAF V600E mutant protein has good sensitivity but not specificity to diagnose PTC. IHC can be used as a preliminary screening method to detect BRAF V600E mutation. The strongly positive (+++) staining of IHC potently indicated BRAF V600E gene mutation. For suspicious thyroid nodules combined with HT, the detection of BRAF V600E mutant protein with IHC alone is not of great significance for differentiating benign and malignant nodules.

Molecular Correlates and Nuclear Features of Encapsulated Follicular-Patterned Thyroid Neoplasms

BACKGROUND

Assessing nuclear features is diagnostically challenging in the aspect of thyroid pathology. The aim of this study was to determine whether pathologists could distinguish BRAF-like and RAS-like nuclear features morphologically and identify morphological features to differentiate thyroid tumors with RAS-like mutations from encapsulated papillary thyroid carcinoma (PTC) with predominant follicular growth and BRAFV600E mutation.

METHODS

Representative whole slide images of 16 encapsulated thyroid tumors with predominant follicular growth were reviewed by 12 thyroid pathologists using a web browser-based image viewer. Total nuclear score was calculated from semi-quantitatively scored eight nuclear features. The molecular profile of RAS and BRAF genes was determined by Sanger sequencing.

RESULTS

Total nuclear score ranging 0 to 24 could differentiate BRAF-like tumors from RAS-like tumors with a cut-off value of score 14. The interobserver agreement was the highest for the assessment of nuclear pseudoinclusions (NPIs) but the lowest for nuclear elongation and sickle-shaped nuclei. NPIs were found in tumors with BRAFV600E mutation, but not in tumors with RAS-like mutations. Total nuclear scores were significantly higher for tumors with BRAFV600E than for those with RAS-like mutations (P&lt;0.001).

CONCLUSION

Our results suggest that NPIs and high nuclear scores have diagnostic utility as rule-in markers for differentiating PTC with BRAFV600E mutation from benign or borderline follicular tumors with RAS-like mutations. Relaxation of rigid criteria for nuclear features resulted in an overdiagnosis of PTC. Immunostaining or molecular testing for BRAFV600E mutation is a useful adjunct for cases with high nuclear scores to identify true PTC.

Comparison of Molecular Methods and BRAF Immunohistochemistry (VE1 Clone) for the Detection of BRAF V600E Mutation in Papillary Thyroid Carcinoma: A Meta-Analysis

The evaluation of surgically resected papillary thyroid carcinomas (PTC) by immunohistochemistry (IHC) for BRAF mutation has diagnostic, prognostic and therapeutic implications. The goal of this meta-analysis was to perform a systematic review of studies using the VE1 clone (specific for detection of the BRAF V600E mutation) on formalin-fixed paraffin embedded (FFPE) thyroid surgical resection specimens for primary papillary thyroid carcinoma. The authors' molecular techniques, immunohistochemistry protocols, and scoring methods for VE1 immunostaining were also evaluated. This study included 4079 PTCs representing data from 23 studies. The results extracted from each study were split into two different groups, direct sequencing group or PCR group, based on the molecular "gold standard" method used to compare VE1 IHC staining. In the direct sequencing group, the IHC sensitivity was 100% (95% CI 0.97-1.00) and specificity 84% (95% 0.72-0.91). In the PCR group the sensitivity was 98% (95% CI 0.96-0.99) and specificity 89% (95% CI 0.82-0.94). Although immunohistochemical procedures varied by author, the overall performance of the VE1 clone shows that it is highly sensitive and relatively specific for detecting the BRAF V600E mutation in surgical resection specimens. However, standardization of immunohistochemical procedural method and scoring/interpretation criteria may improve the reliability and reproducibility for the use of VE1 clone for future practice.

Discrepancy between immunohistochemistry and sequencing for BRAF V600E in odontogenic tumours: Comparative analysis of two VE1 antibodies

BACKGROUND

Although immunohistochemistry (IHC) along with molecular tests has been investigated in ameloblastoma for BRAF V600E detection, VE1 IHC has not been studied in odontogenic carcinomas (OCs) and benign mixed epithelial and mesenchymal odontogenic tumours (BMOTs). Here, we performed BRAF V600E mutation analysis, examined the expression pattern of VE1 IHC, and comparatively evaluated the performance of two VE1 antibodies in ameloblastomas, OCs and BMOTs.

METHODS

BRAF V600E detection was performed using Sanger sequencing in a total of 47 odontogenic tumours: 28 ameloblastomas, 6 OCs and 13 BMOTs. VE1 IHC was conducted using two different antibodies (IHC-A and IHC-V), and their performance was analysed by calculating the sensitivity and specificity compared with sequencing.

RESULTS

BRAF V600E mutations were identified in 24/28 (85.7%) ameloblastomas, 2/5 (40.0%) ameloblastic carcinomas (ACs), 3/7 (42.9%) ameloblastic fibromas and 1/2 (50.0%) ameloblastic fibro-odontomas. In the presence of the mutation, VE1 showed diffuse cytoplasmic staining in ameloblastomas and ACs, whereas all BMOTs were negative for VE1. IHC-A and IHC-V yielded a sensitivity of 76.7% and 60.0%, respectively, although both antibodies showed 100% specificity.

CONCLUSION

OCs and BMOTs have BRAF V600E mutations in common at lower frequencies than ameloblastoma. Diffuse VE1 cytoplasmic staining in AC suggests the utility of MAPK-targeted therapy as selectively applied in ameloblastoma, and consistent VE1 false-negative expression in BMOTs requires further investigation. Considering the high specificity but low sensitivity of VE1 IHC, molecular tests should be performed to determine the presence of BRAF V600E mutations in odontogenic tumours.

Obesity Is Associated with BRAFV600E-Mutated Thyroid Cancer

Background: Thyroid cancer incidence has increased in many parts of the world since the 1980s, as has the prevalence of obesity. Evidence suggests that people with greater body size have higher thyroid cancer risk. However, it is unclear whether this association is causal or is driven by over-diagnosis of indolent cancers, because overweight/obese people use health services more frequently than those of normal weight, thus conferring greater opportunity for incidental diagnosis. Assessing whether obesity is associated with higher-risk thyroid cancers might help clarify this issue. Methods: We recruited 1013 people diagnosed with thyroid cancer between 2013 and 2016 and 1057 population controls, frequency matched by sex and age group. We used logistic regression to assess the association between body mass index (BMI) and overall thyroid cancer risk as well as by tumor BRAF mutational status as a marker of potentially higher-risk cancer. Results: Overall, obesity was associated with greater risk of thyroid cancer (odds ratio [OR] = 1.72; 95% confidence interval [CI 1.37-2.16] for obese vs. normal BMI). The association with obesity was significantly stronger for BRAF-mutation positive than BRAF-negative papillary thyroid cancers (PTCs; OR = 1.71 [CI 1.17-2.50] for BRAF-positive vs. BRAF-negative cancers). The increased risks associated with overweight/obesity did not vary by histological subtypes or presence/absence of adverse tumor histologic features. Conclusions: Greater risk of BRAF-mutated PTCs among those with high BMI suggests that the association may not merely reflect greater health care service use and indicates an independent relationship between obesity and clinically important thyroid cancer.

VE1 Immunohistochemistry Improves the Limit of Genotyping for Detecting BRAFV600E Mutation in Papillary Thyroid Cancer

Detection of BRAF^V600E is useful for making diagnosis and risk stratification of papillary thyroid carcinoma (PTC). Molecular testing, however, is not always available for routine clinical use. To assess the clinical utility and reliability of VE1 immunohistochemistry (IHC) for detecting BRAF^V600E mutation in PTC, VE1 IHC was performed on the tissue microarrays of 514 patients with PTC and was compared with Sanger sequencing results. Of 514 PTC cases, 433 (84.2%) were positive for VE1 expression. Among 6 discordant cases between VE1 IHC and Sanger sequencing, 3 initial VE1-false negative cases turned out to be true false negative on repeat testing, and 3 VE1-false positive cases showed BRAF^V600E mutation using digital PCR analysis. PTCs with low variant allele fraction were positive for VE1 IHC but were not detected using sequencing. VE1 IHC showed 99.3% sensitivity, 100% specificity, 100% positive predictive value, and 96.4% negative predictive value. The BRAF^V600E mutation was significantly associated with older age, multifocality, extrathyroidal extension, lymph node metastasis, and advanced tumor stage. In conclusion, VE1 IHC is a reliable method for detecting BRAF^V600E mutation in PTC specimens.

Carcinomas of the Thyroid with Ewing Family Tumor Elements (CEFTEs): A Diagnostic Challenge Before Surgery

Carcinomas of the thyroid with Ewing family tumor elements (CEFTEs) are small cell thyroid tumors characterized by epithelial differentiation and EWSR1-FLI1 rearrangements. In contrast to primary thyroid Ewing sarcomas, these rare tumors have a favorable prognosis. CEFTEs may co-exist with papillary thyroid carcinoma (PTC) foci and are thought to arise from either PTCs or main cells of solid cell nests (SCN). Due to their rare occurrence, characteristic clinical presentations, preoperatory sonographic (US) findings, and fine-needle aspiration (FNA) cytologic features were ill-defined until now. We report a case of a 40-year-old male who was referred to the thyroid clinic for a progressively enlarging, hard, painless, cervical mass. US examination revealed a hypoechoic nodule with lobulated margins and scant intranodular vascular signals of the right thyroid lobe. Evidence of extracapsular spread was not identified. FNA provided a Bethesda V cytology classification on conventional smears. Repeat FNA sampling with the use of a CytoFoam Core allowed a preoperative diagnosis consistent with undifferentiated thyroid carcinoma. Total thyroidectomy without lymph node dissection was performed. Histologic examination with subsequent molecular studies provided the diagnosis of papillary carcinoma of the thyroid with Ewing family tumour elements (CEFTEs). No additional treatment was rendered and the patient showed no evidence of local or distant disease by clinical examination, US, and ¹⁸FDG-TAC/PET after 6 months of follow-up. This is the first reported case of CEFTE with complete clinical, US, cytologic, and immunohistochemical preoperatory assessment.