Follicular thyroid carcinoma

A bibliometric analysis of follicular thyroid carcinoma: Current situation, hot spots, and global trends

BACKGROUND

Follicular thyroid carcinoma (FTC), the second most prevalent thyroid cancer after papillary thyroid cancer (PTC), tends to metastasize distantly, leading to poorer outcomes. Despite substantial research, a holistic bibliometric analysis of FTC literature is lacking. This study aims to fill this gap by employing bibliometric methods to track FTC research evolution.

METHODS

English FTC publications were systematically gathered from the Web of Science. Bibliometric analysis, using R, VOSviewer, CiteSpace, and Excel, synthesized data and explored global research trends and topics.

RESULTS

From 2000 to 2023, 9086 authors from 1953 institutions across 75 countries contributed to 1776 papers in 491 academic journals on FTC. The last two decades have witnessed a steady increase in publications related to FTC, with the United States leading in terms of publication volume. The United States dominated both in publications and citations, with the National Cancer Institute and Sheue-Yann Cheng as leading contributors. The journal 'Thyroid' featured the most publications, while the 'Journal of Clinical Endocrinology and Metabolism' ranked highest in citation frequency. Research focused on gene expression analysis and preoperative diagnostics, with recent trends shifting toward prognosis management and machine learning due to advances in medical technology and increased health awareness.

CONCLUSION

This comprehensive bibliometric analysis has mapped the landscape of FTC research, highlighting key contributors, institutions, and thematic trends. Current discourse predominantly revolves around genetic analysis, prognostic determinants, and preoperative diagnostics in FTC. This foundational work guides future FTC research, providing insights into its evolution.

RAS-Mutant Follicular Thyroid Tumors: A Continuous Challenge for Pathologists

The classification of thyroid nodules, particularly those with a follicular growth pattern, has significantly evolved. These tumors, enriched with RAS or RAS-like mutations, remain challenging for pathologists due to variables such as nuclear atypia, invasion, mitotic activity, and tumor necrosis. This review addresses the histological correlates of benign, low-risk, and malignant RAS-mutant thyroid tumors, as well as some difficult-to-classify follicular nodules with worrisome features. One prototypical RAS-mutant nodule is non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). The assessment of nuclear characteristics in encapsulated/well-demarcated non-invasive RAS-mutant follicular-patterned tumors helps distinguish between follicular thyroid adenoma (FTA) and NIFTP. Despite this straightforward concept, questions about the degree of nuclear atypia necessary for the diagnosis of NIFTP are common in clinical practice. The nomenclature of follicular nodules lacking clear invasive features with increased mitotic activity, tumor necrosis, and/or high-risk mutations (e.g., TERT promoter or TP53) remains debated. Invasion, particularly angioinvasion, is the current hallmark of malignancy in RAS-mutant follicular-patterned neoplasms, with follicular thyroid carcinoma (FTC) as the model. Assessing the tumor interface is critical, though full capsule evaluation can be challenging. Multiple levels and NRASQ61R-specific immunohistochemistry can aid in identifying invasion. Controversies around vascular invasion persist, with ancillary stains like CD31, ERG, and CD61 aiding in its evaluation. Moreover, the review highlights that invasive encapsulated follicular variant papillary thyroid carcinoma (IEFVPTC) is closely associated with FTC, suggesting the need for better nomenclature. The concept of "high-grade" differentiated carcinomas, applicable to FTC or IEFVPTC with necrosis and/or high mitotic activity, is also discussed.

Differentiating Thyroid Follicular Adenoma from Follicular Carcinoma via G-Protein Coupled Receptor-Associated Sorting Protein 1 (GASP-1)

Follicular neoplasms are classified as benign or malignant depending on the presence or absence of capsular and/or vascular invasion. Due to incomplete capsular penetration or equivocal vascular invasion, the evaluation of these features can be challenging using histologic examination. In the current study, we analyzed the involvement of G-protein coupled receptor-associated sorting protein 1 (GASP-1) in the development and progression of thyroid neoplasms. Affinity-purified anti-GASP-1 polyclonal antibodies were used for routine immunohistochemistry (IHC) analysis. Thyroid tissue microarrays containing normal thyroid tissue, follicular adenoma, follicular carcinoma, papillary thyroid carcinoma, and anaplastic carcinoma were analyzed. We found that the level of GASP-1 expression can differentiate follicular adenoma from follicular carcinoma. When numerous cases were scored for GASP-1 expression by a board-certified pathologist, we found that GASP-1 expression is 7-fold higher in thyroid malignant neoplasms compared to normal thyroid tissue, and about 4-fold higher in follicular carcinoma compared to follicular adenoma. In follicular adenoma tissues, we observed the presence of many mini-glands that are enriched in GASP-1 and some mini-glands contain as few as three cells. GASP-1 IHC also possesses several advantages over the conventional H&E and can be used to identify early thyroid cancer and monitor cancer progression.

Selection Criteria for Completion Thyroidectomy in Follicular Thyroid Carcinoma Using Primary Tumor Size and TERT Promoter Mutational Status

BACKGROUND

A stepwise surgical approach with hemithyroidectomy and completion thyroidectomy was used to achieve definite characterization of follicular thyroid carcinoma (FTC). Choosing appropriate candidates for completion thyroidectomy has been controversial.

OBJECTIVE

The aim of this study was to clarify the selection criteria for completion thyroidectomy using telomerase reverse transcriptase (TERT) promoter mutation.

METHODS

A total of 87 FTC patients who had information about TERT promoter mutation from August 1995 to November 2020 were investigated. The cumulative risk of initial distant metastasis, disease recurrence, and cancer-specific death according to primary tumor size in each of the World Health Organization (WHO) 2017 classifications were calculated.

RESULTS

Of the 87 patients, 8 (9.2%) had initial distant metastasis and 15 (17.2%) had persistent disease or developed structural recurrence. The threshold diameter for initial distant metastasis, disease recurrence, and cancer-specific death was 2 cm in minimally invasive FTC (MI-FTC) with mutant TERT (M-TERT) and in encapsulated angioinvasive FTC (EA-FTC) with M-TERT, while that in MI-FTC with wild-type TERT (WT-TERT) and EA-FTC with WT-TERT was 4 cm. The cumulative risk of initial distant metastasis, disease recurrence, and cancer-specific death according to primary tumor size in each WHO 2017 classification was significantly different only in patients with WT-TERT (p = 0.001, p = 0.019, and p = 0.005, respectively).

CONCLUSIONS

The data suggest 2 cm as a critical threshold diameter for performance of completion thyroidectomy in MI-FTC with M-TERT and EA-FTC with M-TERT. TERT promoter mutational status can help select candidates for completion thyroidectomy.

Multi-Omics and Management of Follicular Carcinoma of the Thyroid

Follicular thyroid carcinoma (FTC) is the second most common cancer of the thyroid gland, accounting for up to 20% of all primary malignant tumors in iodine-replete areas. The diagnostic work-up, staging, risk stratification, management, and follow-up strategies in patients who have FTC are modeled after those of papillary thyroid carcinoma (PTC), even though FTC is more aggressive. FTC has a greater propensity for haematogenous metastasis than PTC. Furthermore, FTC is a phenotypically and genotypically heterogeneous disease. The diagnosis and identification of markers of an aggressive FTC depend on the expertise and thoroughness of pathologists during histopathological analysis. An untreated or metastatic FTC is likely to de-differentiate and become poorly differentiated or undifferentiated and resistant to standard treatment. While thyroid lobectomy is adequate for the treatment of selected patients who have low-risk FTC, it is not advisable for patients whose tumor is larger than 4 cm in diameter or has extensive extra-thyroidal extension. Lobectomy is also not adequate for tumors that have aggressive mutations. Although the prognosis for over 80% of PTC and FTC is good, nearly 20% of the tumors behave aggressively. The introduction of radiomics, pathomics, genomics, transcriptomics, metabolomics, and liquid biopsy have led to improvements in the understanding of tumorigenesis, progression, treatment response, and prognostication of thyroid cancer. The article reviews the challenges that are encountered during the diagnostic work-up, staging, risk stratification, management, and follow-up of patients who have FTC. How the application of multi-omics can strengthen decision-making during the management of follicular carcinoma is also discussed.

Clinical evaluation of malignancy diagnosis of rare thyroid carcinomas by an artificial intelligent automatic diagnosis system

PURPOSE

To evaluate the application value of a generally trained artificial intelligence (AI) automatic diagnosis system in the malignancy diagnosis of rare thyroid carcinomas, such as follicular thyroid carcinoma, medullary thyroid carcinoma, primary thyroid lymphoma and anaplastic thyroid carcinoma and compare the diagnostic performance with radiologists of different experience levels.

METHODS

We retrospectively studied 342 patients with 378 thyroid nodules that included 196 rare malignant nodules by using postoperative pathology as the gold standard, and compared the diagnostic performances of three radiologists (one junior, one mid-level, one senior) and that of AI automatic diagnosis system.

RESULTS

The accuracy of the AI system in malignancy diagnosis was 0.825, which was significantly higher than that of all three radiologists and higher than the best radiologist in this study by a margin of 0.097 with P-value of 2.252 × 10^-16. The mid-level radiologist and senior radiologist had higher sensitivity (0.857 and 0.959) than that of the AI system (0.847) at the cost of having much lower specificity (0.533, 0.478 versus 0.802). The junior radiologist showed relatively balanced sensitivity and specificity (0.816 and 0.549) but both were lower than that of the AI system.

CONCLUSIONS

The generally trained AI automatic diagnosis system showed high accuracy in the differential diagnosis of begin nodules and rare malignancy nodules. It may assist radiologists for screening of rare malignancy nodules that even senior radiologists are not acquainted with.

Challenges in Encapsulated Follicular-Patterned Tumors: How Much Is Enough? Evaluation of Nuclear Atypia, Architecture, and Invasion

Thyroid pathology is notoriously fraught with high interobserver variability, and follicular-patterned tumors are among some of the most challenging to assess accurately and reproducibly. Given that encapsulated or well-circumscribed follicular-patterned tumors often have similar molecular profiles, that is, frequent RAS or RAS-like alterations, the diagnosis usually relies on histopathologic examination alone. Unfortunately, many of the features that are used for diagnosis and prognosis of these tumors have long been controversial and frequently debated topics, both due to their subjectivity and their evolving (or not yet resolved) definitions. In more recent years, the introduction of noninvasive follicular thyroid neoplasm with papillary-like nuclear features has added further complexity to this discussion. In particular, the criteria and significance of nuclear features of papillary thyroid carcinoma, architectural patterns, and invasive growth still pose significant diagnostic challenges and confusion. This review explores some of the challenges in evaluating encapsulated follicular-patterned tumors, focusing on those histologic elements.

Inhibiting ERK dimerization ameliorates BRAF-driven anaplastic thyroid cancer

Background

RAS-to-ERK signaling is crucial for the onset and progression of advanced thyroid carcinoma, and blocking ERK dimerization provides a therapeutic benefit in several human carcinomas. Here we analyzed the effects of DEL-22379, a relatively specific ERK dimerization inhibitor, on the activation of the RAS-to-ERK signaling cascade and on tumor-related processes in vitro and in vivo.

Methods

We used a panel of four human anaplastic thyroid carcinoma (ATC) cell lines harboring BRAF or RAS mutations to analyze ERK dynamics and tumor-specific characteristics. We also assessed the impact of DEL-22379 on the transcriptional landscape of ATC cell lines using RNA-sequencing and evaluated its therapeutic efficacy in an orthotopic mouse model of ATC.

Results

DEL-22379 impaired upstream ERK activation in BRAF- but not RAS-mutant cells. Cell viability and metastasis-related processes were attenuated by DEL-22379 treatment, but mostly in BRAF-mutant cells, whereas in vivo tumor growth and dissemination were strongly reduced for BRAF-mutant cells and mildly reduced for RAS-mutant cells. Transcriptomics analyses indicated that DEL-22379 modulated the transcriptional landscape of BRAF- and RAS-mutant cells in opposite directions.

Conclusions

Our findings establish that BRAF- and RAS-mutant thyroid cells respond differentially to DEL-22379, which cannot be explained by the previously described mechanism of action of the inhibitor. Nonetheless, DEL-22379 demonstrated significant anti-tumor effects against BRAF-mutant cells in vivo with an apparent lack of toxicity, making it an interesting candidate for the development of combinatorial treatments. Our data underscore the differences elicited by the specific driver mutation for thyroid cancer onset and progression, which should be considered for experimental and clinical approaches.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00018-022-04530-9.

Ultrasonographic and cytologic assessments of follicular neoplasms of the thyroid: Predictive features differentiating follicular carcinoma from follicular adenoma

Background

The preoperative diagnosis of follicular neoplasm of the thyroid is challenging due to difficulties in the assessment of capsular invasion. This study aimed to identify ultrasonographic (US) and cytopathologic features that are characteristic of follicular adenoma and carcinoma to aid in their differential diagnosis.

Methods

A total of 98 surgically resected nodules diagnosed as follicular neoplasms between 2011 and 2012 were analyzed. US findings were reviewed according to the Korean Thyroid Imaging Reporting and Data System (K-TIRADS). Six cytologic features (high cellularity, abundant microfollicles, cell crowding/nuclear overlapping, isolated cells, homogeneous nuclei, abundant colloid) were reviewed quantitatively. The radiologic findings and quantification of cytologic features were correlated with final diagnoses.

Results

In total, 70 (71.4%) and 28 (28.6%) of the nodules were follicular adenomas and follicular carcinomas, respectively. US findings of a heterogeneous echogenicity, speculated/ill-defined margin, and presence of calcifications were significantly associated with follicular carcinoma (p<0.05). Calcifications had a predilection for pericapsular areas than for stromal areas in follicular carcinomas, whereas their location was more varied in follicular adenomas. No cytologic feature was significantly different between follicular adenomas and carcinomas.

Conclusion

Distinct from follicular adenomas, follicular carcinomas are characterized by heterogeneous echogenicity, speculated/ill-defined margin, and presence of calcifications on US. Thus, US findings can be helpful to differentiate between these two follicular neoplasms.

Roles of Cadherin2 in Thyroid Cancer

Background

The majority of drug-resistant cells in Thyroid cancer (THCA) tend to exhibit an Epithelial mesenchymal transition (EMT) phenotype, and abnormal expression of the cell adhesion molecule Cadherin2 (CDH2) is a hallmark of EMT. However, the roles of CDH2 in THCA and its underlying mechanisms are unknown.

Methods

We analyzed the CDH2 expression in The Cancer Genome Atlas (TCGA) database and screened for genes positively associated with CDH2. Small interfering RNA and cell transfection were used for knocking down CDH2 in THCA cells, cell counting kit-8 (CCK-8) assay and immunofluorescence to detect cell proliferation. Binding miRNAs of CDH2 and CDH2-associated genes were predicted using the Encyclopedia of RNA Interactomes (ENCORI) database. The expression of genes in clinical THCA tissues was investigated from the Human Protein Atlas (HPA) database and validated by qRT-PCR. We conducted the cell functions pathways of CDH2 and CDH2-associated gene FRMD3 by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. We also showed the correlation between CDH2 and FRMD3 expression and tumor immune infiltration.

Results

The expression of CDH2 was significantly higher in THCA tumor tissues compared to normal tissues. Moreover, there were strongly associations of CDH2 expression with the stages T and N. Cellular function assays showed that CDH2 exerted its growth-promoting activity of THCA. To better understand how CDH2 was regulated in THCA, we sought genes associated with CDH2. Correlation analysis revealed that there were negative correlations between genes (CDH2, FRMD3) and miRNAs (hsa-miR-410-3p, hsa-miR-411-5p, hsa-miR-299-5p). Moreover, CDH2 and FRMD3 expression were significantly higher in tumor tissues than in normal tissues, while hsa-miR-410-3p, hsa-miR-411-5p and hsa-miR-299-5p were significantly decreased in tumor tissues compared with normal tissues in THCA. GO and KEEG results showed that CDH2 and FRMD3 were strongly associated with immune-related functions. High expression of CDH2 and FRMD3 was linked to the suppression of immune cells. There were strong negativity correlations between CDH2, FRMD3 and T-cell exhaustion factors.

Conclusion

Our data indicated that CDH2 and CDH2-related gene FRMD3 might have the critical effects on altering tumors becoming ‘cold tumors’ eventually leading to immune checkpoint inhibitor resistance.

Spatially resolved immune microenvironmental profiling for follicular thyroid carcinoma with minimal capsular invasion

Spatial profiles of the tumor-immune microenvironment are associated with disease progression and clinicopathological factors in various cancers. Follicular thyroid carcinoma (FTC) is the second most common thyroid cancer, where the presence of capsular invasion or angioinvasion determines the pathological diagnosis; however, little is known about the immune microenvironment profiles associated with the acquisition of invasive potential of FTC. In this study, we focused on FTC with minimal capsular invasion, and the spatially resolved immune microenvironment of FTC was studied in the discovery (n = 13) and validation cohorts (n = 40). CD8⁺ T cells, helper T cells, regulatory T cells, B cells, natural killer cells, tumor-associated macrophages, CD66⁺ granulocytes, mature dendritic cells, and mast cells were quantitatively evaluated in single tissue sections, via a 12-marker multiplex immunohistochemistry and image cytometry. Cell densities and compositions of immune cells were spatially stratified by six tissue regions including tumor center, subcapsular region, capsular invasion, adjacent stroma of capsular invasion, peritumoral stroma, and adjacent normal. Lymphoid cell lineages in the tumor center and subcapsular regions were significantly lower than those in adjacent normal and peritumoral stroma, potentially related to the lymphoid lineage exclusion from the intratumoral regions of FTC. Interestingly, immune cell composition profiles in the capsular invasive front were distinct from those of intratumoral region. The ratios of T cells to CD66b⁺ granulocytes with capsular invasion were significantly higher than those without capsular invasion, suggesting the presence of a unique immune microenvironment at the invasive front between tumor foci and stroma. In addition, tumor cells at the capsular invasive front showed significantly higher expression of tumor programmed cell death ligand 1 (PD-L1) than those at the tumor center. This study revealed spatial immune profiles associated with capsular invasion of FTC, providing new insights into the mechanisms underlying its development and initial invasion.

An artificial intelligence ultrasound system's ability to distinguish benign from malignant follicular-patterned lesions

OBJECTIVES

To evaluate the application value of a generally trained artificial intelligence (AI) automatic diagnosis system in the malignancy diagnosis of follicular-patterned thyroid lesions (FPTL), including follicular thyroid carcinoma (FTC), adenomatoid hyperplasia nodule (AHN) and follicular thyroid adenoma (FTA) and compare the diagnostic performance with radiologists of different experience levels.

METHODS

We retrospectively reviewed 607 patients with 699 thyroid nodules that included 168 malignant nodules by using postoperative pathology as the gold standard, and compared the diagnostic performances of three radiologists (one junior, two senior) and that of AI automatic diagnosis system in malignancy diagnosis of FPTL in terms of sensitivity, specificity and accuracy, respectively. Pairwise t-test was used to evaluate the statistically significant difference.

RESULTS

The accuracy of the AI system in malignancy diagnosis was 0.71, which was higher than the best radiologist in this study by a margin of 0.09 with a p-value of 2.08×10^-5. Two radiologists had higher sensitivity (0.84 and 0.78) than that of the AI system (0.69) at the cost of having much lower specificity (0.35, 0.57 versus 0.71). One senior radiologist showed balanced sensitivity and specificity (0.62 and 0.54) but both were lower than that of the AI system.

CONCLUSIONS

The generally trained AI automatic diagnosis system can potentially assist radiologists for distinguishing FTC from other FPTL cases that share poorly distinguishable ultrasonographical features.

Logistic regression analysis of contrast-enhanced ultrasound and conventional ultrasound of follicular thyroid carcinoma and follicular adenoma

Background

Follicular thyroid carcinoma (FTC) is prone to recurrence and hematogenous metastasis, preoperative accurate diagnosis is still needed to help clinicians select the best surgical methods to improve the prognosis of patients. The aim of this study was to find specific conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) characteristics of FTC and to explore their diagnostic value in the differential diagnosis between FTC and follicular adenoma (FA).

Methods

This retrospective study included 258 thyroid follicular neoplasms (172 FAs and 86 FTCs) in 244 consecutive patients who underwent preoperative conventional US, and 72 of them underwent both conventional US and CEUS. Sonograms were reviewed in consensus by two experienced radiologists for various conventional US and CEUS features. Multivariate logistic regression analysis was performed to determine independent risk factors for FTC.

Results

Independent risk factors of conventional US for FTC were heterogenicity (OR =7.477, 95% CI: 2.848-19.629), unevenly thick halo (OR =5.643, 95% CI: 3.234-9.848) and calcifications (OR =1.748, 95% CI: 1.098-2.783). While independent risk factors determined with the combination of CEUS and conventional US were unevenly thick halo (OR =5.770, 95% CI: 1.310-25.409) and absent or irregular rim enhancement (OR =27.000, 95% CI: 2.445-298.178). The area under the receiver operating characteristic curve of the final two logistic regression models was 0.835 and 0.838.

Conclusions

Conventional US is an efficient diagnostic tool in the differential diagnosis of FTC and FA to help clinicians in making appropriate decisions while CEUS failed to provide additional diagnostic value in the study, thus the value of CEUS remains to be verified by further studies with larger sample sizes.

Osteopontin Expression in Thyroid Cancer: Deciphering EMT-Related Molecular Mechanisms

Thyroid cancer is the most common tumor arising from the endocrine system and generally presents good prognosis. However, its aggressive subtypes are related to therapeutic resistance and early metastasis. Epithelial–mesenchymal transition (EMT) and its reverse process, the mesenchymal–epithelial transition (MET), are key events mediating cancer progression, including in thyroid cancer. The matricellular protein osteopontin (OPN) has been reported as a master regulator of EMT in many tumor types. Although high OPN expression has been described and associated with important aspects of thyroid cancer progression, there is no clear evidence regarding OPN as a regulator of EMT in thyroid cancer. Thus, taking together the known roles of OPN in the modulation of EMT in cancer and the information reporting the expression of OPN in thyroid tumor progression, this review aims at summarizing and discussing data related to EMT in thyroid cancer and its putative relation to the roles of OPN in the development of thyroid cancer. These data provide new insights into the molecular mechanisms by which OPN could potentially modulate EMT in thyroid tumors, generating evidence for future studies that may contribute to new therapeutic, prognostic and/or diagnostic tools.

Surgical Considerations in Thyroid Cancer: What the Radiologist Needs to Know

Management of thyroid cancer requires a multidisciplinary approach including head and neck/endocrine surgeons, endocrinologists, oncologists, and radiologists. The radiographic evaluation of thyroid cancer is critical for complete and precise staging and affects the surgical approach to address these cancers. The purpose of this article is to briefly review the common thyroid cancer pathologies and surgical considerations in thyroid cancer, focusing on the extent of surgery and the influence of preoperative imaging on surgical decision-making. This article assumes that a diagnosis of thyroid cancer has been made and does not discuss the workup or surveillance of thyroid nodules.

Application of thermography in the diagnostic investigation of thyroid nodules

Thyroid nodules (TN) are common in the general population, and the clinical importance of diagnosing thyroid nodules is based on excluding the possibility of thyroid cancer, which occurs in 7-15% of cases. The thyroid gland, owing to its superficial location, is easily accessible via thermography, a noninvasive method of recording body temperature that measures infrared radiation emitted by the body surface. Therefore, this study aimed to evaluate the temperature differences between benign and malignant TN by using thermography. We conducted a cross-sectional study where 147 TN were divided into two groups: the first group included 120 benign nodules and the other included 27 malignant nodules. All the nodules were subjected to ultrasound, fine needle aspiration biopsy, and thermography. On analyzing the thermography results, the benign nodules had a higher temperature at the beginning of the thermography evaluation, and the malignant nodules showed a higher temperature in the middle and at the end (Ft). Using the relationships, it was observed that the temperature delta (ΔT), ΔT nodule/ΔT healthy, ΔT nodule minus ΔT healthy, and nodule Ft minus Ft of the healthy region were higher in malignant nodules. The ROC curve analysis of ΔT demonstrated a cutoff point of 2.38°C, with a sensitivity of 0.963 and specificity of 0.992. Malignant nodules have higher temperatures than benign nodules on thermographic evaluation. This finding suggests that thermography can be a useful tool in the diagnosis of thyroid nodules.

Genetics of Familial Non-Medullary Thyroid Carcinoma (FNMTC)

Non-medullary thyroid carcinoma (NMTC) is the most frequent endocrine tumor and originates from the follicular epithelial cells of the thyroid. Familial NMTC (FNMTC) has been defined in pedigrees where two or more first-degree relatives of the patient present the disease in absence of other predisposing environmental factors. Compared to sporadic cases, FNMTCs are often multifocal, recurring more frequently and showing an early age at onset with a worse outcome. FNMTC cases show a high degree of genetic heterogeneity, thus impairing the identification of the underlying molecular causes. Over the last two decades, many efforts in identifying the susceptibility genes in large pedigrees were carried out using linkage-based approaches and genome-wide association studies, leading to the identification of susceptibility loci and variants associated with NMTC risk. The introduction of next-generation sequencing technologies has greatly contributed to the elucidation of FNMTC predisposition, leading to the identification of novel candidate variants, shortening the time and cost of gene tests. In this review we report the most significant genes identified for the FNMTC predisposition. Integrating these new molecular findings in the clinical data of patients is fundamental for an early detection and the development of tailored therapies, in order to optimize patient management.

Additional Tissue Sampling Trials Did Not Change Our Thyroid Practice

Simple Summary

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

Abstract

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

Frozen section in thyroid gland follicular neoplasms: It's high time to abandon it!

Thyroid nodules are a very common clinical condition. The 2015 American Thyroid Association (ATA) guidelines recommend surgical excision for Bethesda IV nodules. The use of intraoperative frozen section (FS) has been recommended as a strategy to tailor the extent of the initial surgery. We critically evaluated the literature that discusses the utility and cost-effectiveness of FS to make an intraoperative decision in patients with thyroid nodules classified as follicular neoplasm. FS should not be recommended as a routine intraoperative test to assess for malignancy in thyroid follicular patterned lesions due to its low performance; the high number of deferred results; the inability to adequately assess histologically defining features; the improvements in risk stratification guiding total thyroidectomy; and the low cost-effectiveness of FS.

A Novel Nanoproteomic Approach for the Identification of Molecular Targets Associated with Thyroid Tumors

A thyroid nodule is the most common presentation of thyroid cancer; thus, it is extremely important to differentiate benign from malignant nodules. Within malignant lesions, classification of a thyroid tumor is the primary step in the assessment of the prognosis and selection of treatment. Currently, fine-needle aspiration biopsy (FNAB) is the preoperative test most commonly used for the initial thyroid nodule diagnosis. However, due to some limitations of FNAB, different high-throughput “omics” approaches have emerged that could further support diagnosis based on histopathological patterns. In the present work, formalin-fixed paraffin-embedded (FFPE) tissue specimens from normal (non-neoplastic) thyroid (normal controls (NCs)), benign tumors (follicular thyroid adenomas (FTAs)), and some common types of well-differentiated thyroid carcinoma (follicular thyroid carcinomas (FTCs), conventional or classical papillary thyroid carcinomas (CV-PTCs), and the follicular variant of papillary thyroid carcinomas (FV-PTCs)) were analyzed. For the first time, FFPE thyroid samples were deparaffinized using an easy, fast, and non-toxic method. Protein extracts from thyroid tissue samples were analyzed using a nanoparticle-assisted proteomics approach combined with shotgun LC-MS/MS. The differentially regulated proteins found to be specific for the FTA, FTC, CV-PTC, and FV-PTC subtypes were analyzed with the bioinformatic tools STRING and PANTHER showing a profile of proteins implicated in the thyroid cancer metabolic reprogramming, cancer progression, and metastasis. These proteins represent a new source of potential molecular targets related to thyroid tumors.

Micronuclei Formation upon Radioiodine Therapy for Well-Differentiated Thyroid Cancer: The Influence of DNA Repair Genes Variants

Radioiodine therapy with ¹³¹I remains the mainstay of standard treatment for well-differentiated thyroid cancer (DTC). Prognosis is good but concern exists that ¹³¹I-emitted ionizing radiation may induce double-strand breaks in extra-thyroidal tissues, increasing the risk of secondary malignancies. We, therefore, sought to evaluate the induction and 2-year persistence of micronuclei (MN) in lymphocytes from 26 ¹³¹I-treated DTC patients and the potential impact of nine homologous recombination (HR), non-homologous end-joining (NHEJ), and mismatch repair (MMR) polymorphisms on MN levels. MN frequency was determined by the cytokinesis-blocked micronucleus assay while genotyping was performed through pre-designed TaqMan^® Assays or conventional PCR-restriction fragment length polymorphism (RFLP). MN levels increased significantly one month after therapy and remained persistently higher than baseline for 2 years. A marked reduction in lymphocyte proliferation capacity was also apparent 2 years after therapy. MLH1 rs1799977 was associated with MN frequency (absolute or net variation) one month after therapy, in two independent groups. Significant associations were also observed for MSH3 rs26279, MSH4 rs5745325, NBN rs1805794, and tumor histotype. Overall, our results suggest that ¹³¹I therapy may pose a long-term challenge to cells other than thyrocytes and that the individual genetic profile may influence ¹³¹I sensitivity, hence its risk-benefit ratio. Further studies are warranted to confirm the potential utility of these single nucleotide polymorphisms (SNPs) as radiogenomic biomarkers in the personalization of radioiodine therapy.

DNA FISH Diagnostic Assay on Cytological Samples of Thyroid Follicular Neoplasms

Simple Summary

Cytopathology cannot distinguish benign from malignant follicular lesions in 20–30% of cases. These indeterminate cases includes the so-called follicular neoplasms (FNs) according to The Bethesda System for Reporting Thyroid Cytopathology. Frozen samples from 66 classic follicular adenomas (cFAs) and carcinomas (cFTCs) studied by array-comparative genomic hybridization identified three specific alterations of cFTCs (losses of 1p36.33-35.1 and 22q13.2-13.31, and gain of whole chromosome X) confirmed by fluorescent in situ hybridization (FISH) in a second independent series of 60 touch preparations from frozen samples of cFAs and cFTCs. In a third independent set of 27 cases of already stained pre-operative fine-needle aspiration cytology samples diagnosed as FNs and histologically verified, FISH analysis using these three markers identified half of cFTCs. Specificity of our assay for identifying cFTCs is higher than 98% which might be comparable with BRAF^600E testing in cases of suspicion of classic papillary thyroid carcinomas.

Abstract

Although fine-needle aspiration cytology (FNAC) is helpful in determining whether thyroid nodules are benign or malignant, this distinction remains a cytological challenge in follicular neoplasms. Identification of genomic alterations in cytological specimens with direct and routine techniques would therefore have great clinical value. A series of 153 cases consisting of 72 and 81 histopathologically confirmed classic follicular adenomas (cFAs) and classic follicular thyroid carcinomas (cFTCs), respectively, was studied by means of different molecular techniques in three different cohorts of patients (pts). In the first cohort (training set) of 66 pts, three specific alterations characterized by array comparative genomic hybridization (aCGH) were exclusively found in half of cFTCs. These structural abnormalities corresponded to losses of 1p36.33-35.1 and 22q13.2-13.31, and gain of whole chromosome X. The second independent cohort (validation set) of 60 pts confirmed these data on touch preparations of frozen follicular neoplasms by triple DNA fluorescent in situ hybridization using selected commercially available probes. The third cohort, consisting of 27 archived cytological samples from an equal number of pts that had been obtained for preoperative FNAC and morphologically classified as and histologically verified to be follicular neoplasms, confirmed our previous findings and showed the feasibility of the DNA FISH (DNA fluorescent in situ hybridization) assay. All together, these data suggest that our triple DNA FISH diagnostic assay may detect 50% of cFTCs with a specificity higher than 98% and be useful as a low-cost adjunct to cytomorphology to help further classify follicular neoplasms on already routinely stained cytological specimens.

Reciprocal Dysregulation of MiR-146b and MiR-451 Contributes in Malignant Phenotype of Follicular Thyroid Tumor

Over the last few years, incidental thyroid nodules are being diagnosed with increasing frequency with the use of highly sensitive imaging techniques. The ultrasound thyroid gland examination, followed by the fine-needle aspiration cytology is the standard diagnostic approach. However, in cases of the follicular nature of nodules, cytological diagnosis is not enough. Analysis of miRNAs in the biopsy presents a promising approach. Increasing our knowledge of miRNA's role in follicular carcinogenesis, and development of the appropriate the miRNA analytical technologies are required to implement miRNA-based tests in clinical practice. We used material from follicular thyroid nodes (n.84), grouped in accordance with their invasive properties. The invasion-associated miRNAs expression alterations were assayed. Expression data were confirmed by highly sensitive two-tailed RT-qPCR. Reciprocally dysregulated miRNAs pair concentration ratios were explored as a diagnostic parameter using receiver operation curve (ROC) analysis. A new bioinformatics method (MiRImpact) was applied to evaluate the biological significance of the observed expression alterations. Coupled experimental and computational approaches identified reciprocal dysregulation of miR-146b and miR-451 as important attributes of follicular cell malignant transformation and follicular thyroid cancer progression. Thus, evaluation of combined dysregulation of miRNAs relevant to invasion and metastasis can help to distinguish truly malignant follicular thyroid cancer from indolent follicular adenoma.

Solitary metastatic deposit in the mandible from follicular thyroid carcinoma

Follicular thyroid carcinoma (FTC) is the second most common cancer of the thyroid, after papillary carcinoma. Oral metastasis arising from FTC is very rare. Mandible is more commonly affected than maxilla, with the premolar–molar region being the most frequent site of metastasis. We present the case of a 68yearold female, with swelling in the region of the parotid gland, complaining of periodic rightsided pain in the temporomandibular joint, which occurred most often in the morning with numbness and pain, and difficulty in opening the mouth. After ultrasound and X-ray, the patient was operated and the pathohistological finding was in favor of metastasis of FTC. After 3 months, a total thyroidectomy was performed, and FTC was detected in the right thyroid lobe. Laboratory results were as follows: FT₄ = 9.92 pmol/L, thyroid-stimulating hormone = 9.9 mIU/L, and hTG >300 μg/L. Bone scan showed no bone metastasis. Radioablation with ¹³¹I of 150 mCi was given to the patient, followed by substitutional therapy with levothyroxine. Mandible metastasis as a single skeletal deposit from follicular thyroid carcinomas is a rare clinical finding. Maxillofacial surgeons should consider and rule out thyroid pathology before performing operation of tumor formation in the mandible region. If feasible, surgical-based treatment options offer the best survival outcomes.

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.

Tumor detection of the thyroid and salivary glands using hyperspectral imaging and deep learning

The performance of hyperspectral imaging (HSI) for tumor detection is investigated in ex-vivo specimens from the thyroid (N = 200) and salivary glands (N = 16) from 82 patients. Tissues were imaged with HSI in broadband reflectance and autofluorescence modes. For comparison, the tissues were imaged with two fluorescent dyes. Additionally, HSI was used to synthesize three-band RGB multiplex images to represent the human-eye response and Gaussian RGBs, which are referred to as HSI-synthesized RGB images. Using histological ground truths, deep learning algorithms were developed for tumor detection. For the classification of thyroid tumors, HSI-synthesized RGB images achieved the best performance with an AUC score of 0.90. In salivary glands, HSI had the best performance with 0.92 AUC score. This study demonstrates that HSI could aid surgeons and pathologists in detecting tumors of the thyroid and salivary glands.

Overexpression of mir-129-1, miR-146b, mir-183, and mir-197 in follicular thyroid carcinoma and adenoma tissues

Follicular thyroid carcinoma (FTC) is responsible for approximately 10% of thyroid malignancies. Since this type of malignancy indicates no capsular and vascular invasions, adenoma and follicular carcinoma of thyroid are not distinguishable. It has been proved that microRNAs, which regulate approximately 30% of coding proteins, have an association with follicular thyroid adenoma (FTA) and carcinoma of the thyroid. Therefore, the aim of this study was to assess the expression of some miRNAs for detecting the most appropriate miRNA as potential biomarker in the diagnosis of FTA and FTC patients. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was applied to determine the expression levels of miR-129-1, miR-146b,-183 and miR-197 in 48 cases (16 FTC, 16 FTA and 16 hyperplasia/multinodular goiter (MNG) cases). The significance of miRNA differential expression levels among groups were assessed using Multivariate test by Statistical Package for Science Software (SPSS v.20) and Graph Pad Prism v.8. Results indicated that all of the miRNAs had significant overexpression in FTC and FTA versus MNG cases, and also increased expression level in FTC in comparison with FTA, however it was not significant. The results of ROC curve analysis determined the significant overexpression and prognostic value of miR-129-1 in FTA cases and miR-146b in both FTA and FTC cases compared to MNG group. Although all of the earlier mentioned microRNAs were overexpressed in FTC and FTA cases, the ROC curve results demonstrated that miR-129-1 had agreeable AUC for FTA cases. Therefore, it seems that it's cut-off point could be helpful in distinguishing between FTA and multinodular goiter cases. On the other hand, although miR-146b has excellent diagnostic value in both FTA and FTC groups, it seems that this microRNA is unable to act as a specific biomarker to discriminate between FTA and FTC cases. This data need to be confirmed in a large cohort study and other biological samples such as plasma.

Prognostic factors in thyroid carcinomas: a 17-year outcome study

Objectives The aim of our study was to evaluate the survival rate of all thyroid carcinomas (TCs) diagnosed in the 1999-2015 period in the Republic of North Macedonia and to analyze the prognostic influence of several characteristics on development of distant metastases, as well as to analyze the prognostic effect of seven clinical and constitutional features on mortality. Material and methods A retrospective analysis of medical data from all TCs diagnosed in 1999-2015 was performed. The survival rate of all types of TCs was estimated using the Kaplan Meier method. Univariate and multivariate logistic regression analysis was applied for evaluation of the predictive role of seven clinical and constitutional characteristics for development of distant metastases, and the univariate Cox-proportional model was applied for evaluation of the predictors for mortality. Results A total of 422 TC cases were diagnosed in the 17-year period, with an average survival time of 212.99 months. Results of the univariate regression analysis showed that dimension at initial ultrasound and histopathological type of tumor were significantly predictive variables for distant metastases. Multifocal tumors vs. unifocal tumors < 15 mm significantly increased the probability of distant metastases by 7.401 (p = 0.005, 95% CI = 1.817-30.190) times. Age, initial lymph node involvement, number of radioiodine therapies, and histopathology of the tumor were selected as independent significant predictors for mortality. Conclusion Our results showed an excellent overall prognosis of thyroid tumors in the Macedonian population. The dimension of the tumor, multifocality, and histopathological type were the most relevant prognostic predictive features for development of distant metastases.

Minimally invasive parathyroid carcinoma-A missing entity between parathyroid adenoma and carcinoma: Scintigraphic and histological features

PURPOSE

Minimally invasive parathyroid carcinoma (MIPC) is clinically and biochemically comparable with parathyroid adenoma (PA) though histopathologically differ from PA. MIPC is an intermediate of PA and parathyroid carcinoma (PC). In literature, there is no definite criterion to diagnose MIPC. Our aim was to evaluate and characterize the imaging and biochemical parameters with histological characteristics of MIPC.

METHODOLOGY

Ten patients with MIPC were recruited from (single centre) Indian PHPT registry (www.indianphptregistry.com) from January 2014 to July 2018. Clinical, biochemical, imaging and histological features of MIPC patients were reviewed.

RESULTS

The mean age of MIPC patients (n = 10; 3 males) was 39.9 ± 11.3 years (range: 17-50). All patients had an elevated preoperative parathyroid hormone (iPTH) level ranging from 427 to 2138 pg/mL (median: 1328). MIBI scan showed intensely avid and enlarged parathyroid tumours in all patients; LIPT in 6, RIPT in 3 and ectopic mediastinal in 1 with mean size of the tumours was 2.8 ± 1.1 cm. The mean of maximum standardized uptake value (SUVmax) of MIPC in F-18 fluorocholine PET/CT was 6.7 ± 1.1 (range 6.0-8.3). The mean tumour weight was 12 ± 9.5 g (range: 1.09-28). All MIPC patients had identified capsular invasion in 80% and vascular invasion in 50% only but there was no local invasion, lymph nodal or distant metastasis. The mean Ki-67 labelling index was 3.2 ± 2.7 (range 1.1-10).

CONCLUSION

The study concluded that MIPC patients are less aggressive (on the basis of imaging and histopathological findings) and should be differentiated from parathyroid adenoma and carcinoma.

High-Resolution Raman Microscopic Detection of Follicular Thyroid Cancer Cells with Unsupervised Machine Learning

We use Raman microscopic images with high spatial and spectral resolution to investigate differences between human follicular thyroid (Nthy-ori 3-1) and follicular thyroid carcinoma (FTC-133) cells, a well-differentiated thyroid cancer. Through comparison to classification of single-cell Raman spectra, the importance of subcellular information in the Raman images is emphasized. Subcellular information is extracted through a coarse-graining of the spectra at high spatial resolution (∼1.7 μm²), producing a set of characteristic spectral groups representing locations having similar biochemical compositions. We develop a cell classifier based on the frequencies at which the characteristic spectra appear within each of the single cells. Using this classifier, we obtain a more accurate (89.8%) distinction of FTC-133 and Nthy-ori 3-1, in comparison to single-cell spectra (77.6%). We also infer which subcellular components are important to cellular distinction; we find that cancerous FTC-133 cells contain increased populations of lipid-containing components and decreased populations of cytochrome-containing components relative to Nthy-ori 3-1, and that the regions containing these contributions are largely outside the cell nuclei. In addition to increased classification accuracy, this approach provides rich subcellular information about biochemical differences and cellular locations associated with the distinction of the normal and cancerous follicular thyroid cells.

[Tumors of the thyroid gland. Proposal for the management and study of samples from patients with thyroid neoplasms]

The recent changes in the classification and staging of thyroid tumors have arisen from the need to provide an adequate response to the exponential increase of thyroid cancer, which, however, has not been accompanied by an increase in mortality. These changes pretend to reduce overdiagnoses of malignancy, unnecessary treatment, side effects as well as cost for the health system. To this end, this article reviews recommendations for the management of thyroid surgical pathology samples with emphasis on the new terminology of the WHO classification. The basic criteria for the diagnosis of malignancy in well-differentiated thyroid carcinomas are reviewed and the criteria for NIFTP (non-invasive follicular tumor with papillary-like nuclear features) diagnosis are updated. Recommendations for the elaboration of the pathological report are also included.

Microsatellite Instability Occurs in a Subset of Follicular Thyroid Cancers

BACKGROUND

Inactivation of DNA mismatch repair (MMR) and the resulting microsatellite instability (MSI) are frequently observed in endometrial, stomach, and colorectal cancers, as well as more rarely in other solid tumor types. The prevalence of MSI in thyroid cancer has not been explored in depth, although recent studies utilizing data from large cancer sequencing efforts such as The Cancer Genome Atlas indicate that MSI is absent or at least very rare in the most common and most well studied histologic subtype, papillary thyroid carcinoma. This study aimed to determine the prevalence of MSI in thyroid cancer by using a large series comprising all major histological subtypes.

METHODS

A total of 485 thyroid cancer patients were screened for MSI/MMR deficiency, including all major histologic subtypes (195 papillary thyroid carcinoma, 156 follicular thyroid carcinoma [FTC], 50 anaplastic thyroid carcinoma, 65 medullary thyroid carcinoma, and 17 poorly differentiated thyroid carcinomas) by using a combination of polymerase chain reaction-based detection, immunohistochemistry, and next-generation sequencing.

RESULTS

A total of four tumors were MSI-high and had loss of MMR protein expression, all of which were from FTC patients. Whole-exome sequencing was performed on two MSI-high FTCs and revealed a hemizygous loss of function mutation in MSH2 in one tumor.

CONCLUSIONS

Based on these data, it is estimated that the overall prevalence of MSI in FTC is 2.5%, and MSI is either entirely absent or rare in other histology subtypes of thyroid carcinoma. These findings highlight the importance of testing for MSI in FTC.

Association between DNA methylation profile and malignancy in follicular-patterned thyroid neoplasms

Molecular differentiation between benign (follicular thyroid adenoma, FTA) and malignant (follicular thyroid carcinoma, FTC) thyroid neoplasms is challenging. Here, we explored the genome-wide DNA methylation profile of FTA (n.10) and FTC (n.11) compared to normal thyroid (NT) (n.7) tissues. FTC featured 3,564 differentially-methylated CpGs (DMCpG), most (84%) of them hypermethylated, with respect to normal controls. At the principal component analysis (PCA), the methylation profile of FTA occupied an intermediate position between FTC and normal tissue. A large fraction (n. 2,385) of FTC-associated DMCpG were related (intragenic or within 1500 bp from the transcription start site) to annotated genes (n. 1,786). FTC-hypermethylated genes were enriched for targets of the Polycomb transcriptional repressor complex and the specific histone H3 marks (H3K4me2/me3-H3K27me3) found in chromatin domains known as "bivalent". Transcriptome profiling by RNAseq showed that 7.9% of the DMCpGs-associated genes were differentially expressed in FTC compared to NT, suggesting that altered DNA methylation may contribute to their altered expression. Overall, this study suggests that perturbed DNA methylation, in particular hypermethylation, is a component of the molecular mechanisms leading to the formation of FTC and that DNA methylation profiling may help differentiating FTCs from their benign counterpart.

In Silico Integration Approach Reveals Key MicroRNAs and Their Target Genes in Follicular Thyroid Carcinoma

To better understand the molecular mechanism for the pathogenesis of follicular thyroid carcinoma (FTC), this study aimed at identifying key miRNAs and their target genes associated with FTC, as well as analyzing their interactions. Based on the gene microarray data GSE82208 and microRNA dataset GSE62054, the differentially expressed genes (DEGs) and microRNAs (DEMs) were obtained using R and SAM software. The common DEMs from R and SAM were fed to three different bioinformatic tools, TargetScan, miRDB, and miRTarBase, respectively, to predict their biological targets. With DEGs intersected with target genes of DEMs, the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed through the DAVID database. Then a protein-protein interaction (PPI) network was constructed by STRING. Finally, the module analysis for PPI network was performed by MCODE and BiNGO. A total of nine DEMs were identified, and their function might work through regulating hub genes in the PPI network especially KIT and EGFR. KEGG analysis showed that intersection genes were enriched in the PI3K-Akt signaling pathway and microRNAs in cancer. In conclusion, the study of miRNA-mRNA network would offer molecular support for differential diagnosis between malignant FTC and benign FTA, providing new insights into the potential targets for follicular thyroid carcinoma diagnosis and treatment.

European Perspective on 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: Proceedings of an Interactive International Symposium

BACKGROUND

The American Thyroid Association (ATA) management guidelines for patients with thyroid nodules and differentiated thyroid cancer (DTC) are highly influential practice recommendations. The latest revision appeared in 2015 ("ATA 2015"). These guidelines were developed predominantly by North American experts. European experts frequently have different perspectives, given epidemiological, technological/methodological, practice organization, and medicolegal differences between the respective regions.

SUMMARY

Divergent viewpoints were the focus of an invited symposium organized by the European Association of Nuclear Medicine involving 17 European thyroidologists, four ATA Guidelines Taskforce members, and an audience of 200 international experts. The group discussed the preoperative assessment of thyroid nodules, surgery and the role of pathology, radioiodine (RAI) therapy (RAIT), the assessment of initial therapy and dynamic risk stratification, and the treatment of persistent disease, recurrences, and advanced thyroid cancer. The dialogue resulted in this position paper contrasting European and ATA 2015 perspectives on key issues. One difference pertains to the permissiveness of ATA 2015 regarding lobectomy for primary tumors ≤4 cm. European panelists cited preclusion of RAIT, potential need for completion thyroidectomy, frequent inability to avoid chronic thyroid hormone replacement, and limitations of supportive evidence as arguments against widely applying lobectomy. Significant divergence involved ATA 2015's guidance regarding RAIT. European panelists favored wider use of postoperative RAIT than does ATA 2015. Rationales included the modality's association with favorable patient outcomes and generally limited toxicity, and lack of high-quality evidence supporting withholding RAIT. Additionally, European panelists favored recombinant human thyrotropin (rhTSH) in more settings than does ATA 2015, citing avoidance of hypothyroid morbidity and quality-of-life impairment, without apparent sacrifice in oncologic outcomes. Based on clinical evidence plus theoretical advantages, European experts advocated dosimetric versus fixed-activity RAIT approaches for advanced DTC. European panelists noted that the ATA 2015 risk-stratification system requires information sometimes unavailable in everyday practice. ATA 2015 recommendations regarding RAI-refractory DTC should consider potential palliative benefits of RAIT in patients who also have RAI-susceptible lesions.

CONCLUSIONS

European panelists suggested modifications to approximately one-third of ATA 2015 recommendations. Varying European and ATA 2015 perspectives can stimulate analysis and discussion of the literature and performance of primary research to resolve discrepant recommendations and potentially improve patient outcomes.

Proteome profiles of different types of thyroid cancers

Proteomics profiling of tissue specimens representative for major types of thyroid cancers: papillary (classical and follicular variant), follicular, anaplastic and medullary, as well as benign follicular adenoma, was performed using shotgun LC-MS/MS approaches. A combination of Orbitrap and MALDI-TOF approach allowed to identify protein products of 3700 unique genes and revealed large differences between medullary, anaplastic and epithelium-derived differentiated cancers (papillary and follicular). Proteins characteristic for medullary and anaplastic cancers included factors associated with neuroendocrine functions and factors typically associated with advanced malignancies, respectively. Proteomes of different types of epithelium-derived differentiated cancers and follicular adenoma were compared using multi-enzyme LC-MS/MS approach, which revealed products of 4800 unique genes. A comparable overall similarity of follicular cancers to both variants of papillary cancers was found. Moreover, follicular adenoma showed higher overall similarity to follicular cancer than to either variant of papillary cancer. Proteins discriminating differentiated thyroid neoplasms included factors associated with lipid and hormone metabolism, regulation of gene expression and maintenance of DNA structure. Importantly, proteome data matched several features of transcriptome and metabolome profiles of thyroid cancers contributing to systems biology of this malignancy.

Clinicopathological Risk Factors for Distant Metastasis in Differentiated Thyroid Carcinoma: A Meta-analysis

INTRODUCTION

Distant metastasis (DM) is not a frequent event in differentiated thyroid carcinoma (DTC) but has an adverse impact on mortality of patients with DTC. In the current study, we aimed to conduct a comprehensive systematic review and meta-analysis to investigate the risk factors for DM in DTCs and for each histological subtype.

METHODS

Five electronic databases were searched from inception to December 2016 for relevant articles. Pooled odd ratios and 95% confidence interval were calculated using random-effect model.

RESULTS

Thirty-four articles with 73,219 patients were included for meta-analyses. In DTCs, male gender, age ≥45 years, tumor size ≥4 cm, multifocality, vascular invasion (VI), extrathyroidal extension (ETE), lymph node metastasis (LNM), and lateral LNM were demonstrated to be associated with significant risks for DM. In addition, several clinicopathological factors such as age ≥45 years, VI, ETE, and LNM were shown to be significant risk factors for DM in both PTC and FTC subgroups.

CONCLUSION

Our study demonstrated the promising value of several clinicopathological factors such as male gender, older age, VI, ETE, and LNM in predicting DM in PTCs and FTCs. Our study affirms the value of the selected clinicopathological factors for tumor risk stratification and assessment of patients' prognosis.

Pituitary Metastasis of Thyroid Carcinoma: A Case Report

BACKGROUND Pituitary metastasis of thyroid carcinoma is a rare entity. Differential diagnosis with other lesions in the sellar/parasellar region, through clinical, histopathological, immunohistochemical, and imaging is challenging but essential for adequate treatment. CASE REPORT This case report describes a 58-year-old patient with the previous diagnosis of follicular thyroid carcinoma, with metastasis to cervical lymph nodes, bone, and lung, initially evolving to left palpebral ptosis. In the investigation, laboratory tests showed hypopituitarism, and magnetic resonance imaging of the skull showed a suprasellar formation measuring 2.2×3.5×2.5 cm, which increased in size in a few months. The patient underwent transcranial neurosurgery and subsequent immunohistochemical analysis, which confirmed pituitary metastasis of follicular thyroid carcinoma. The patient underwent chemotherapy and radiotherapy but died 26 months after the onset of symptoms. CONCLUSIONS The differential diagnosis of pituitary metastasis from a benign lesion is difficult. Therefore, a careful analysis of the history and clinical evolution, use of complementary imaging tests, and, where possible, the histopathological and immunohistochemical analysis of the lesion for diagnostic elucidation are necessary.

Follicular thyroid cancer and Hürthle cell carcinoma: challenges in diagnosis, treatment, and clinical management

Follicular thyroid cancer is the second most common differentiated thyroid cancer histological type and has been overshadowed by its more common counterpart-papillary thyroid cancer-despite its unique biological behaviour and less favourable outcomes. In this Review, we comprehensively review the literature on follicular thyroid cancer to provide an evidence-based guide to the management of these tumours, to highlight the lack of evidence behind guideline recommendations, and to identify changes and challenges over the past decades in diagnosis, prognosis, and treatment. We highlight that correct identification of cancer in indeterminate cytological samples is challenging and ultrasonographic features can be misleading. Despite certain unique aspects of follicular thyroid cancer presentation and prognosis, no specific recommendations exist for follicular thyroid cancer and Hürthle cell carcinoma in evidence-based guidelines. Efforts should be made to stimulate additional research in this field.

Tumour growth rate of follicular thyroid carcinoma is not different from that of follicular adenoma

OBJECTIVE

Distinguishing malignancy from benign thyroid nodule has always been challenging, especially in follicular lesions. Thyroid nodules with small size and indeterminate cytology do not lead to immediate surgery. We tried to evaluate whether tumour size and tumour growth rate can distinguish follicular thyroid carcinoma (FTC) from follicular adenoma (FA).

DESIGN AND PATIENTS

This retrospective study included patients with pathologically proven FTCs (n = 50) and FAs (n = 110) who underwent preoperative serial neck ultrasonography (US) at least 3 times: it comprises 30% of all follicular tumours (32% FAs and 25% FTCs). The growth rates of follicular tumours on serial US were measured using at least 3 consecutive examinations during a median follow-up of 4.1 years (range, 0.7-13.3 years) by experienced radiologists.

RESULTS

The FA and FTC groups showed no significant difference in clinicopathological characteristics, including age, proportion of large nodules (>4 cm) and preoperative cytology. The maximum diameter of thyroid nodule was gradually increased in both groups with statistical significance (P < .001 and P < .001, respectively). No significant differences in change of maximum diameter of thyroid nodule (P = .132) and tumour volume (P = .208) were found between the FA and FTC groups during the follow-up. The median time to a significant tumour growth from baseline was not different between the FA and FTC groups (1.4 years and 1.7 years, respectively, P = .556). When we divided the patients into four groups (rapid, moderate, slow and no growth) according to the growth velocity of the thyroid tumours, no significant difference in growth velocity was found among the groups.

CONCLUSIONS

The tumour size and growth rate of the thyroid nodule itself could not predict malignancy. Diagnostic approaches that use molecular markers would be more important than clinical features for the decision of diagnostic surgery for patients with follicular tumours.

Encapsulated Follicular Variant of Thyroid Papillary Carcinoma - Case Report and Differential Diagnosis Discussion

Papillary carcinoma is the most common type of epithelial thyroid cancer in women, especially in the reproductive period, accounting for about 75-80% of well-differentiated cancers at this level. One of its variants, follicular encapsulated thyroid carcinoma, is a well-differentiated malignant tumor with good prognosis which, despite the presence of vascular and capsular invasion, rarely causes metastasis, if fully resected. We present the case of a young patient who presented with dysphagia and a painless cystic nodular lesion of the thyroid, and underwent thyroidectomy. The histopathological diagnosis of the lesion was a challenge, being based on the correlation of clear criteria, given the existence of numerous lesions with follicular pattern in the thyroid.

Importance of Number of Foci of Capsular Invasion in Follicular Thyroid Carcinoma

The importance of capsular invasion in follicular thyroid carcinoma (FTC) has not been extensively studied. The aim of the present study was to correlate the clinical features and outcome of FTC with histology features particularly emphasizing on the importance of the number of foci of capsular invasion. This was a retrospective study. Histology of 123 FTC patients was reviewed. Patients were divided in three groups based on the number of foci of vascular and capsular invasion noted in primary tumor: group 1-capsular invasion at <6 and vascular invasion at <4 foci, group 2-either capsular invasion ≥6 or vascular invasion at ≥4 foci, and group 3-capsular invasion ≥6 and vascular invasion at ≥4 foci. Different prognostic factors and overall survival (OS) were compared among the groups. The incidences of distant metastases (p = 0.008) and OS (p = <0.001) were significantly different among the groups. On univariate analysis, age (p = 0.001), tumor size (p = <0.0001), distant metastases (p = <0.0001), vascular invasion (p = 0.018), and capsular invasion (p = 0.003) were significantly associated with OS. On multivariate analysis, age (p = 0.020), distant metastases (p = 0.045), and foci of capsular invasion (p = 0.005) were significant. The number of foci of capsular invasion seems to have significant prognostic value in widely invasive FTC.

Thyroid follicular adenomas and carcinomas: molecular profiling provides evidence for a continuous evolution

Non-autonomous thyroid nodules are common in the general population with a proportion found to be cancerous. A current challenge in the field is to be able to distinguish benign adenoma (FA) from preoperatively malignant thyroid follicular carcinoma (FTC), which are very similar both histologically and genetically. One controversial issue, which is currently not understood, is whether both tumor types represent different molecular entities or rather a biological continuum. To gain a better insight into FA and FTC tumorigenesis, we defined their molecular profiles by mRNA and miRNA microarray. Expression data were analyzed, validated by qRT-PCR and compared with previously published data sets. The majority of deregulated mRNAs were common between FA and FTC and were downregulated, however FTC showed additional deregulated mRNA. Both types of tumors share deregulated pathways, molecular functions and biological processes. The additional deregulations in FTC include the lipid transport process that may be involved in tumor progression. The strongest candidate genes which may be able to discriminate follicular adenomas and carcinomas, CRABP1, FABP4 and HMGA2, were validated in independent samples by qRT-PCR and immunohistochemistry. However, they were not able to adequately classify FA or FTC, supporting the notion of continuous evolving tumors, whereby FA and FTC appear to show quantitative rather than qualitative changes. Conversely, miRNA expression profiles showed few dysregulations in FTC, and even fewer in FA, suggesting that miRNA play a minor, if any, role in tumor progression.

CRABP1, C1QL1 and LCN2 are biomarkers of differentiated thyroid carcinoma, and predict extrathyroidal extension

Background

The prognostic variability of thyroid carcinomas has led to the search for accurate biomarkers at the molecular level. Follicular thyroid carcinoma (FTC) is a typical example of differentiated thyroid carcinomas (DTC) in which challenges are faced in the differential diagnosis.

Methods

We used high-throughput paired-end RNA sequencing technology to study four cases of FTC with different degree of capsular invasion: two minimally invasive (mFTC) and two widely invasive FTC (wFTC). We searched by genes differentially expressed between mFTC and wFTC, in an attempt to find biomarkers of thyroid cancer diagnosis and/or progression. Selected biomarkers were validated by real-time quantitative PCR in 137 frozen thyroid samples and in an independent dataset (TCGA), evaluating the diagnostic and the prognostic performance of the candidate biomarkers.

Results

We identified 17 genes significantly differentially expressed between mFTC and wFTC. C1QL1, LCN2, CRABP1 and CILP were differentially expressed in DTC in comparison with normal thyroid tissues. LCN2 and CRABP1 were also differentially expressed in DTC when compared with follicular thyroid adenoma. Additionally, overexpression of LCN2 and C1QL1 were found to be independent predictors of extrathyroidal extension in DTC.

Conclusions

We conclude that the underexpression of CRABP1 and the overexpression of LCN2 may be useful diagnostic biomarkers in thyroid tumours with questionable malignity, and the overexpression of LCN2 and C1QL1 may be useful for prognostic purposes.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3948-3) contains supplementary material, which is available to authorized users.

Differentiation of the Follicular Neoplasm on the Gray-Scale US by Image Selection Subsampling along with the Marginal Outline Using Convolutional Neural Network

We conducted differentiations between thyroid follicular adenoma and carcinoma for 8-bit bitmap ultrasonography (US) images utilizing a deep-learning approach. For the data sets, we gathered small-boxed selected images adjacent to the marginal outline of nodules and applied a convolutional neural network (CNN) to have differentiation, based on a statistical aggregation, that is, a decision by majority. From the implementation of the method, introducing a newly devised, scalable, parameterized normalization treatment, we observed meaningful aspects in various experiments, collecting evidence regarding the existence of features retained on the margin of thyroid nodules, such as 89.51% of the overall differentiation accuracy for the test data, with 93.19% of accuracy for benign adenoma and 71.05% for carcinoma, from 230 benign adenoma and 77 carcinoma US images, where we used only 39 benign adenomas and 39 carcinomas to train the CNN model, and, with these extremely small training data sets and their model, we tested 191 benign adenomas and 38 carcinomas. We present numerical results including area under receiver operating characteristic (AUROC).