Do benign thyroid nodules have malignant potential? An evidence-based review

TERT promoter mutations and additional molecular alterations in thyroid fine-needle aspiration specimens: A multi-institutional study with histopathologic follow-up

OBJECTIVES

TERT promoter mutations are not infrequently encountered in thyroid carcinomas; however, it is unclear if additional molecular alterations may play a role in determining tumor behavior.

METHODS

Fine-needle aspiration (FNA) specimens from 32 patients with TERT promoter mutations detected by ThyroSeq v3 from 4 institutions were included in the study. FNA diagnoses, molecular results, and surgical follow-up were retrospectively reviewed and analyzed.

RESULTS

There were 5 benign and 27 malignant neoplasms, including 7 high-grade thyroid carcinomas (HGCs) on histopathologic follow-up. Of 4 cases with an isolated TERT mutation, 3 (75%) cases were malignant. Of 17 cases harboring a co-occurring TERT mutation with 1 additional molecular alteration, 13 (76%) displayed malignancy on histopathologic follow-up. All 11 cases with TERT mutations plus 2 or more additional molecular alterations were malignant on follow-up. Furthermore, HGC was not seen in cases with an isolated TERT mutation, while 80% of cases harboring TERT mutations plus 3 additional molecular alterations showed HGC.

CONCLUSIONS

TERT promoter mutations are commonly associated with malignancy, particularly HGCs, when multiple co-occurring molecular alterations are present. However, TERT promoter mutations may occasionally be detected in benign thyroid neoplasms when encountered in isolation or with fewer than 2 additional molecular alterations.

EIF1AX mutation in thyroid nodules: a histopathologic analysis of 56 cases in the context of institutional practices

EIF1AX mutation has been identified as a driver mutation for papillary thyroid carcinoma (PTC) by The Cancer Genome Atlas (TCGA) study. Subsequent studies confirmed this mutation in PTC and Anaplastic Thyroid Carcinoma (ATC) but also reported EIF1AX mutation in Follicular nodular disease (FND) and benign thyroid nodules. In this study, we review thyroid nodules with EIF1AX mutation from two institutions: a tertiary care hospital (YNHH, n = 22) and a major cancer referral center (MSKCC, n = 34) and report the varying histomorphology in the context of additional genetic abnormalities and institutional practices. Pathology diagnoses were reviewed according to the WHO 5th edition and correlated with the type of EIF1AX mutation and additional concurrent molecular alterations, if any. Most cases were splice site type mutations. Cases consisted of 9 FND, 7 follicular (FA) or oncocytic adenomas (OA), 2 non-invasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP) and 38 follicular-cell derived thyroid carcinomas. Of 8 cases with isolated EIF1AX mutation, 7 were FND, FA or OA (88%) and one was an oncocytic carcinoma (12%). Of 12 cases with EIF1AX and one additional molecular alteration, 9 (75%) were FND, FA or OA, 2 (17%) were NIFTPs and one (8%) was a poorly differentiated thyroid carcinoma. All 36 cases with EIF1AX mutation and ≥ 2 molecular alterations were malignant (100%) and included TP53 and TERT promoter mutations associated with ATC (n = 8) and high-grade follicular cell-derived non-anaplastic carcinoma (HGC, n = 2). Isolated EIF1AX mutation was noted only in thyroid nodules seen at YNHH and were predominantly encountered in benign thyroid nodules including FND. Accumulation of additional genetic abnormalities appears to be progressively associated with malignant tumors.

"Copy number alteration" as the sole molecular finding of a Thyroseq test is more commonly seen in Hurthle cell neoplasms

BACKGROUND

To better understand the molecular alterations associated with Hurthle cell lesions of the thyroid, we retrospectively reviewed the association of clonal DNA copy number alterations (CNAs) with fine needle aspiration (FNA) cytomorphology and surgical follow-up.

METHODS

Hurthle cell type (HCT) and non-Hurthle cell type (NHCT) thyroid FNAs that were classified according to the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) as atypia of undetermined significance (AUS) and suspicious for a follicular neoplasm (SFN) with corresponding molecular testing performed by ThyroSeq v3 genomic classifier were compared to surgical follow-up.

RESULTS

A total of 54 thyroid FNA cases were identified, distributed among the following categories: AUS-HCT (n = 15, 27.8%), SFN-HCT (n = 11, 20.4%), AUS-NHCT (n = 19, 35.2%), and SFN-NHCT (n = 9, 16.6%). The lesions classified as AUS-HCT and SFN-HCT showed a higher prevalence of CNAs (n = 10/26; 38.5%) compared to their NHCT counterparts (n = 3/28; 10.7%) (p < .03). Of the 42 patients (77.8%) with surgical follow-up, CNAs were more often seen in benign (n = 10/26, 38.5%) than malignant conditions (n = 1/16, 6.3%) (p < .03). CNAs were encountered in more lesions with Hurthle cell features on histologic examination (n = 8/14, 57.1%) than those without (n = 3/28, 10.7%) (p < .002). The presence of CNAs alone was seen only in benign adenomas and more commonly with Hurthle cell features (n = 5/7, 71.4%).

CONCLUSION

In this study, CNAs were associated with Hurthle cell morphology on thyroid FNA and benign adenomas upon surgical follow-up. Therefore, if the only finding of a positive ThyroSeq v3 GC result is a CNA, conservative management can be considered if clinically indicated.

A new paradigm for epidermal growth factor receptor expression exists in PTC and NIFTP regulated by microRNAs

Intoduction

Identification of molecular alterations associated with tumor behavior is necessary to guide clinical management. The 2022 WHO classification has organized the thyroid follicular cell-derived neoplasms into benign, low-risk and high-risk neoplasms, and emphasized the value of biomarkers that may provide differential diagnostic and prognostic information to avoid overtreatment of low risk neoplasms. This work aims to study the epidermal growth factor receptor (EGFR) expression, functional and spatial dynamics in relation to specific miRNAs alterations in papillary thyroid cancer (PTC) and in non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) considered as models of high-risk and low-risk thyroid tumors respectively.

Methods

Primary thyroid cultured cells were used for miRNA gain/loss of function and luciferase reporter assays. Paraffin embedded tissues were used for real time PCR, immuno-fluorescence stain and confocal microscopy experiments.

Results

Our results showed that in PTC, EGFR mRNA is reduced as an effect of miR-146b-5p upregulation. The EGF expression is low and the ERK pathway is inhibited. The EGFR protein high cytoplasmic expression and colocalization with the endosomal/exosomal markers, ALIX and CD63, suggest the occurrence of stress-induced EGFR internalization, accumulation in endosomal vesicles and secretion via exosomes. In NIFTP EGFR transcription is increased in association with downregulation of miR-7-5p and the EGFR/ERK pathway is active indicating dependence on the canonical EGFR pathway for growth.

Conclusion

Downregulation of transcript level along with cytoplasmic accumulation of undegraded protein is a new pattern of EGFR regulation associated with malignancy in thyroid. Further research is needed to elucidate the intracellular trafficking defects responsible for this specific EGFR dynamic in PTC.

Copy number variations identified in thyroid FNA specimens are associated with Hürthle cell cytomorphology

BACKGROUND

The fine-needle aspiration (FNA) diagnosis of thyroid Hürthle cell neoplasms (HCNs) remains challenging. This study explored a possible association of copy number variations (CNVs) with Hürthle cell lesions of the thyroid.

METHODS

Thyroid FNA cases that were diagnosed as follicular lesion of undetermined significance (FLUS) or follicular neoplasm (FN)/HCN for which the ThyroSeq version 3 genomic classifier test was performed were retrieved.

RESULTS

A total of 324 thyroid FNA cases (228 FLUS cases, 46 HCN cases, and 50 FN cases) were included in the study. FLUS cases were further classified as Hürthle cell type (follicular lesion of undetermined significance-Hürthle cell type [FLUS-HCT]; 20 cases) or non-Hürthle cell type (follicular lesion of undetermined significance-non-Hürthle cell type [FLUS-NHCT]; 208 cases). HCN and FLUS-HCT cases showed a higher prevalence of CNVs (23 of 66 [35%]) in comparison with those classified as FN or FLUS-NHCT (14 of 258 [5%]; P < .001). A total of 105 patients had histopathologic follow-up. Cases with CNVs were more likely to be neoplastic (18 of 26 [69%]) and associated with Hürthle cell changes (14 of 26 [54%]) in comparison with cases without any molecular alterations (neoplastic, 8 of 24 [33%]; Hürthle cell changes, 2 of 24 [8%]; P < .05). In HCN/FLUS-HCT cases with CNVs (n = 14), Hürthle cell changes (13 of 14 [93%]) and neoplasms (9 of 14 [64%]) were more likely to be seen on surgical follow-up in comparison with the 17 cases without CNVs (Hürthle cell changes, 6 of 17 [35%]; neoplastic, 3 of 17 [18%]; P < .05).

CONCLUSIONS

CNVs identified in thyroid FNA cases are associated with Hürthle cell morphology and are suggestive of a neoplasm with Hürthle cell features in thyroid FNAs classified as FLUS-HCT/HCN. This finding may be helpful in triaging patients who would benefit from surgical management.

Emerging Role of Oxidative Stress on EGFR and OGG1-BER Cross-Regulation: Implications in Thyroid Physiopathology

Thyroid diseases have a complex and multifactorial aetiology. Despite the numerous studies on the signals referable to the malignant transition, the molecular mechanisms concerning the role of oxidative stress remain elusive. Based on its strong oxidative power, H2O2 could be responsible for the high level of oxidative DNA damage observed in cancerous thyroid tissue and hyperactivation of mitogen-activated protein kinase (MAPK) and PI3K/Akt, which mediate ErbB signaling. Increased levels of 8-oxoG DNA adducts have been detected in the early stages of thyroid cancer. These DNA lesions are efficiently recognized and removed by the base excision repair (BER) pathway initiated by 8-oxoG glycosylase1 (OGG1). This study investigated the relationships between the EGFR and OGG1-BER pathways and their mutual regulation following oxidative stress stimulus by H2O2 in human thyrocytes. We clarified the modulation of ErbB receptors and their downstream pathways (PI3K/Akt and MAPK/ERK) under oxidative stress (from H2O2) at the level of gene and protein expression, according to the mechanism defined in a human non-pathological cell system, Nthy-ori 3-1. Later, on the basis of the results obtained by gene expression cluster analysis in normal cells, we assessed the dysregulation of the relationships in a model of papillary thyroid cancer with RET/PTC rearrangement (TPC-1). Our observations demonstrated that a H2O2 stress may induce a physiological cross-regulation between ErbB and OGG1-BER pathways in normal thyroid cells (while this is dysregulated in the TPC-1 cells). Gene expression data also delineated that MUTYH gene could play a physiological role in crosstalk between ErbB and BER pathways and this function is instead lost in cancer cells. Overall, our data on OGG1 protein expression suggest that it was physiologically regulated in response to oxidative modulation of ErbB, and that these might be dysregulated in the signaling pathway involving AKT in the progression of thyroid malignancies with RET/PTC rearrangements.

Radiofrequency ablation and thyroid nodules: updated systematic review

PURPOSE

In the thyroid gland, radiofrequency ablation (RFA) is being applied to both benign nodules and cancers internationally, while interest is also growing in the West. Benign thyroid nodules (BTNs) may be candidates for intervention when symptoms develop. For differentiated thyroid cancers (DTC), surgery is currently the first-line treatment. However, for candidates with high surgical risk or those who refuse to undergo repeated surgery, newer techniques such as RFA are an option. Surgery is associated with complications including hypothyroidism, voice change, hypocalcemia, and a scar. RFA has been used in Asian and European institutions as an alternative to surgery, but is relatively new in North America. Although RFA is not associated with significant complications, few randomized control trials have assessed its efficacy. The studies to date suggest a low rate of severe complications and a small need for thyroid hormone replacement following RFA. Further large-scale studies focusing on a Western population are needed. The aim of this review is to evaluate the evidence with respect to the current studies and data about the safety and efficacy of radiofrequency ablation for the management of BTNs and DTC.

METHODS

We systematically searched the PubMed/MEDLINE, EMBASE, Clinical Queries, and Web of Science databases, for articles published up to April 30th, 2020.

RESULTS

Total of 75 studies that met the inclusion criteria were included in the review. Thirty-five studies focused on RFA use for solid nodules, 12 studies on predominantly cystic nodules, 10 for autonomously functioning thyroid nodules, and 18 studied were published on differentiated thyroid cancer.

CONCLUSIONS

RFA seems to be an effective and safe alternative to surgery in high-risk surgical patients with thyroid cancers and for selected BTNs. Additional trials with longer follow-up in North American patients are needed to validate its full role in the armamentarium of thyroid ologists.

RFA and benign thyroid nodules: Review of the current literature

Benign thyroid nodules (BTNs) are commonly found in the general population. They are usually asymptomatic and their incidence has increased as a result of wide-spread use of ultrasound. Benign nodules are typically monitored clinically until they increase in size, resulting in compressive symptoms warranting surgery. However, although surgery is generally well-tolerated and of low-risk, it is associated with a small risk for several complications including hypothyroidism, nerve injury, hematoma, injury to other structures and wound infection. Recently, newer image-guided ablation techniques including radiofrequency ablation (RFA) have been introduced. RFA has a similar safety profile when compared to surgery and has shown promising results in challenging surgical candidates. Though several studies have been published in Asian and European countries on the efficacy of RFA, limited data is available on the North American population. The aim of the study is to review the current literature establishing the clinical outcomes and safety of RFA for benign nodules.

LEVEL OF EVIDENCE

V.

Efficacy of Microwave Ablation in the Treatment of Large (≥3 cm) Benign Thyroid Nodules

BACKGROUND

Large (≥3 cm) benign thyroid nodules usually cause clinical symptoms or cosmetic concerns and therefore require treatment. Microwave ablation (MWA) is a potential valid non-surgical treatment alternative, but there is a lack of evidence. Thus, this study is to evaluate the safety and efficacy of MWA in the treatment of large benign thyroid nodules.

METHODS

A retrospective study was conducted on 42 large benign thyroid nodules in 40 patients treated with MWA. We used the trans-isthmic approach and moving-shot technique to perform the procedure under ultrasound (US) guidance. Patients were followed by clinical and US examinations at 1, 3, 6, and 12 months after the MWA. Study outcomes were complications, volume reduction ratio (VRR), symptom and cosmetic scores, and the requirement of multiple MWA sessions.

RESULTS

There were 31 females and 9 males, with a median age of 46 years. The medians of largest diameter and volume of the nodules were 40 mm and 22 ml. Four (10%) minor complications were observed. The mean VRR was 75.1, 85.2, and 96.4% after 3, 6, and 12 months. The mean symptom and cosmetic scores dropped from 8.0 and 3.8 (before treatment) to 2.8 and 2.3 (at 12 months), respectively. Thirteen nodules (31%) required two MWA sessions.

CONCLUSIONS

MWA is safe, effective, and can be a good option to treat large benign thyroid nodules. More studies with large dataset and long follow-up are required to improve its safety and efficacy.

Adrenal metastasis as the initial diagnosis of synchronous papillary and follicular thyroid cancer

Background

Differentiated thyroid cancer uncommonly presents with distant metastases. Adrenal metastasis from differentiated thyroid cancer presenting as the initial finding is even less common.

Case Presentation

A 71-year-old male was incidentally found on chest CT to have bilateral thyroid nodules, which were confirmed on ultrasound. Fine needle aspiration of the dominant right 3.3 cm nodule contained histologic features most consistent with Bethesda classification III, and repeat fine needle aspiration revealed pathology consistent with Bethesda classification II. Follow-up thyroid ultrasound showed 1% increase and 14% increase in nodule volume at one and two years, respectively, compared to baseline. Prior to the second annual thyroid ultrasound, the patient was incidentally found to have a 4.1 cm heterogeneously enhancing mass in the right adrenal gland on CT of the abdomen and pelvis. Biochemical evaluation was unremarkable with the exception of morning cortisol of 3.2 µg/dL after dexamethasone suppression. The patient then underwent laparoscopic right adrenal gland excision, which revealed metastatic follicular thyroid carcinoma. Total thyroidectomy was then performed, with pathology showing a 4.8 cm well-differentiated follicular thyroid carcinoma of the right lobe, a 0.5 cm noninvasive follicular thyroid neoplasm with papillary-like nuclear features of the left lobe, and a 0.1 cm papillary microcarcinoma of the left lobe. Thyrotropin-stimulated whole body scan showed normal physiologic uptake of the remnant thyroid tissue without evidence of other iodine avid disease. The patient then received radioactive iodine. At follow-up 14 months after total thyroidectomy, he remains free of recurrent disease.

Conclusion

Despite following the recommended protocol for evaluation and surveillance of thyroid nodules, thyroid cancer can be challenging to diagnose, and may not be diagnosed until distant metastases are identified.

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

Background

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

Materials and methods

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

Results

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

Conclusion

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

Epidemiologic, Clinical, Ultrasonographic, and Cytological Features of Thyroid Nodules in Predicting Malignancy Risk: A Retrospective Study of 442 French Afro-Caribbean Patients

OBJECTIVE

To evaluate epidemiologic, clinical, cytological, and ultrasonographic features of thyroid nodules in a sample French Afro-Caribbean population to determine if the standard criteria for predicting malignancy risk are applicable to this specific ethnic population. Methods and Design. This retrospectively designed study consisted of 442 patients who had consulted with the Endocrinology Department in Martinique (French overseas department) between 2007 and 2011. Of the 442 patients, 641 ultrasound-guided fine-needle aspirations (US-FNA) were performed by two experienced endocrinologists, and 212 patients underwent surgery. The geographical situation, age, gender of the patient, clinical and ultrasonographic features, TSH level, and US-FNA results were considered and cross-referenced with their pathology results.

RESULTS

The overall malignancy rate on final histopathology was 9% (women only), 80% of which were papillary cancer, and 20% were follicular cancer. Occult micropapillary carcinoma represented 35% of the papillary cancer. There was no significant difference in age, nodule localization, number of nodules, or thyroid function test between benign and malignant nodules. Contrary to the literature, we found only 12% incidentaloma in our series, while more than half of the nodules were discovered on palpation or as a clinical symptom. Hypoechogenicity in solid pattern nodules and nodules between 2 and 3 cm in size revealed a high diagnostic value in detecting malignancy. The corresponding rate of malignancy on Bethesda system histopathologic examination was as follows: 0% in undiagnosed (I), 0% benign (II) (micropapillary), 5% (FLUS)/atypia (III), 9% follicular neoplasm (IV), 33% suspected malignancy (V), and no malignant cytology (VI). These results show a different Bethesda system predictive value for this French Afro-Caribbean population.

CONCLUSION

Studies evaluating ethnic cancer disparities among patients with thyroid cancer are limited and do not specifically focus on the French Afro-Caribbean population. Despite rare thyroid incidentaloma, 35% of the papillary cancer cases were micropapillary carcinoma, and the incidence and standardized mortality rate in Martinique are lower than in metropolitan France. The malignant risk distribution of thyroid FNA Bethesda classification in this sample population differs from the standard risk, and it is necessary to take that into account in the decision to operate by associating it with echographic malignancy criteria.

Incidence of and Risk Factors for Histologically Confirmed Solid Benign Tumors Among Long-term Survivors of Childhood Cancer

Importance

Survivors of childhood cancer (CCSs) face risk of developing subsequent tumors. Solid benign tumors may be cancer precursors; benign tumors and cancers may share etiologic factors. However, comprehensive data on the risk for solid benign tumors are lacking.

Objective

To quantify the incidence of and treatment-related risk factors for histologically confirmed solid nonskin benign tumors among CCSs.

Design, Setting, and Participants

This record linkage study involves the Dutch Childhood Oncology Group-Long-Term Effects After Childhood Cancer (DCOG-LATER) cohort of 6165 individuals diagnosed with childhood cancer at younger than 18 years from January 1, 1963, through December 31, 2001, in 7 Dutch pediatric centers and who survived at least 5 years after the diagnosis. Study groups eligible for record linkage from 1990 onward included 5843 CCSs (94.8%) and 883 siblings. Benign tumors were identified from the population-based Dutch histopathology and cytopathology registry (PALGA). Follow-up was completed on May 1, 2015. Data were analyzed from January 1, 1990, through May 1, 2015.

Main Outcomes and Measures

Cumulative incidence of any subsequent benign tumor for cohort strata and multivariable Cox proportional hazards regression models (hazard ratios [HRs]) were used to evaluate potential risk factors for 8 major benign tumor subtypes.

Results

Of the 5843 eligible CCSs (55.9% male), 542 (9.3%) developed a histologically confirmed subsequent benign tumor after a median follow-up of 22.7 years (range, 5.0-52.2 years). Among women, abdominopelvic radiotherapy inferred dose-dependent increased risks for uterine leiomyoma (n = 43) for doses of less than 20 Gy (HR, 1.9; 95% CI, 0.5-7.0), 20 to less than 30 Gy (HR, 3.4; 95% CI, 1.1-10.4), and at least 30 Gy (HR, 5.4; 95% CI, 2.4-12.4) compared with no abdominopelvic radiotherapy (P = .002 for trend). High-dose radiotherapy to the trunk was not associated with breast fibroadenoma (n = 45). Of 23 osseous and/or chondromatous neoplasms, 16 occurred among leukemia survivors, including 11 after total body irradiation (HR, 37.4; 95% CI, 14.8-94.7). Nerve sheath tumors (n = 55) were associated with radiotherapy (HR at 31 years of age, 2.9; 95% CI, 1.5-5.5) and a crude indicator of neurofibromatosis type 1 or 2 status (HR, 5.6; 95% CI, 2.3-13.7). Subsequent risk for benign tumors was higher than the risks for subsequent nonskin solid malignant neoplasms and for benign tumors among siblings.

Conclusions and Relevance

This record linkage study uses a unique resource for valid and complete outcome assessment and shows that CCSs have an approximately 2-fold risk of developing subsequent benign tumors compared with siblings. Site-specific new findings, including for uterine leiomyoma, osteochondroma, and nervous system tumors, are important to enable early diagnosis; this information will be the first step for future surveillance guidelines that include some benign tumors in CCSs and will provide leads for in-depth etiologic studies.

Radiofrequency Ablation for Benign Thyroid Nodules: 1-Year Follow-Up in 184 Patients

BACKGROUND

Benign thyroid nodules are common, and must be treated when symptomatic. Non-surgical minimally invasive modalities, including radiofrequency ablation (RFA), have been widely used with good results. The factors related to the efficacy of RFA are still debated. This study was to evaluate the safety, efficacy and related factors of RFA in the treatment of benign thyroid nodules.

METHODS

A retrospective single-center study was conducted on 251 benign thyroid nodules in 184 patients treated with RFA. The procedure was performed under ultrasound (US) guidance using the trans-isthmic approach and the moving-shot technique. Clinical and US examinations were performed at 1, 3, 6, 12 months, and then at 6 month intervals. Study outcomes were volume reduction ratio (VRR) and complications.

RESULTS

There were 153 women and 31 men included in the study. The mean age was 43.9 years. The median initial largest diameter and volume of nodules were 30 mm and 6.18 ml. The median length of follow-up was 12 months. Two minor complications were found. The mean VRR was 66.8; 74.3; and 81% after 3, 6, and 12 months, respectively. Initial solidity was a factor related to the efficacy: cystic nodules had higher VRR compared to solid ones.

CONCLUSIONS

RFA is safe, effective and can be used as a routine treatment for benign thyroid nodules. More prospective multicenter studies with long-term follow-up are required to improve the safety and efficacy of RFA.

DNA methylation in thyroid cancer

In recent years, cancer genomics has provided new insights into genetic alterations and signaling pathways involved in thyroid cancer. However, the picture of the molecular landscape is not yet complete. DNA methylation, the most widely studied epigenetic mechanism, is altered in thyroid cancer. Recent technological advances have allowed the identification of novel differentially methylated regions, methylation signatures and potential biomarkers. However, despite recent progress in cataloging methylation alterations in thyroid cancer, many questions remain unanswered. The aim of this review is to comprehensively examine the current knowledge on DNA methylation in thyroid cancer and discuss its potential clinical applications. After providing a general overview of DNA methylation and its dysregulation in cancer, we carefully describe the aberrant methylation changes in thyroid cancer and relate them to methylation patterns, global hypomethylation and gene-specific alterations. We hope this review helps to accelerate the use of the diagnostic, prognostic and therapeutic potential of DNA methylation for the benefit of thyroid cancer patients.

Association of benign thyroid diseases with thyroid cancer risk: a meta-analysis of prospective observational studies

PURPOSE

Evidence showed that benign thyroid disease was one of the risk factors for thyroid cancer. However, the results of some studies were inconsistent and were previously meta-analyses of case-control studies. Therefore, we performed a meta-analysis of prospective studies to investigate the relationship between benign thyroid diseases and thyroid cancer risk.

METHODS

All eligible studies were identified via systematic searches of multiple literature databases. The combined RR (relative risk)/HR (hazard ratio) or SIR (standardized incidence ratio) with 95% confidence interval was calculated. Heterogeneity was assessed with the I² test. Publication bias and subgroup analyses were also performed.

RESULTS

Twelve studies were eligible for inclusion in the meta-analysis. The pooled RR/HR of thyroid carcinoma in benign thyroid diseases was 4.39 (95% CI 3.22-5.55). The pooled SIR of thyroid carcinoma in benign thyroid diseases was 5.98 (95% CI 4.09-7.86). Subgroup analysis was performed using the type of benign thyroid diseases. Effect value was RR/HR: hyperthyroidism (RR/HR = 3.89, 95% CI = 1.69-6.08), hypothyroidism (RR/HR = 2.72, 95% CI = 1.04-4.41), and goiter (RR/HR = 22.18, 95% CI = 12.09-32.28). Effect value was SIR: hyperthyroidism (RR/HR = 5.96, 95% CI = 1.88-10.03), goiter (RR/HR = 7.65, 95% CI = 6.94-8.37), and thyroiditis (RR/HR = 3.25, 95% CI = 1.62-4.89).

CONCLUSIONS

Our study has shown that benign thyroid diseases might be associated with increased risk of thyroid cancer, especially in hyperthyroidism, hypothyroidism, and goiter. However, further investigation is needed to better understand the underlying biological mechanisms.

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.

Large Cytologically Benign Thyroid Nodules Do Not Have High Rates of Malignancy or False-Negative Rates and Clinical Observation Should be Considered: A Meta-Analysis

Background: Management of large thyroid nodules is controversial, as data are conflicting regarding overall rates of malignancy (ROM) in all nodules and frequency of false-negative fine-needle aspiration results (FNR) in cytologically benign nodules. This meta-analysis aimed to evaluate and compare ROM and FNR in small versus large nodules published in the literature. Methods: Articles indexed in PubMed, written in English, published electronically or in print on or prior to December 8 2017 were searched for "false negative thyroid size or cm" and "malignancy rates benign thyroid nodules." Three hundred fifty-two unique citations were identified. Multiple reviewers selected a final set of 35 articles that contained nodules stratified by size (3, 4, or 5 cm), with benign or all cytologic diagnoses, and with postsurgical histologic diagnoses. Multiple observers extracted data, including numbers of total, cytologically benign, and histologically malignant nodules. Size cutoffs of 3, 4, and/or 5 cm were analyzed in 14, 24, and 1 article, respectively. Results: ROM in all nodules ≥3 cm (13.1%) and ≥4 cm (20.9%) was lower than those <3 cm (19.6%) and <4 cm (19.9%; odds ratio [OR] = 0.72 [confidence interval (CI) 0.64-0.81] and OR = 0.85 [CI 0.77-0.95]). FNR in nodules ≥3 cm (7.2%) was not different from smaller nodules (5.7%; OR = 1.47 [CI 0.80-2.69]). FNR in nodules ≥4 cm (6.7%) was slightly higher than those <4 cm (4.5%; OR = 1.38 [CI 1.06-1.80]). The most frequently reported false-negative diagnosis was papillary thyroid carcinoma. Conclusions: Rates of malignancy and false-negative FNA results vary but, in most studies, are not higher in larger nodules. Patients with large, cytologically benign thyroid nodules need not undergo immediate surgical resection, as false-negative FNA rates are low and are expected to decrease in light of nomenclature revision of a subset of follicular variants of papillary thyroid carcinoma.

Association of obesity and diabetes with thyroid nodules

AIM

There are conflicting data concerning the possibility that obesity and diabetes raise the risk of thyroid nodules. The incidence of thyroid nodules is increasing, as is that of obesity and diabetes; therefore, understanding whether these metabolic and nutritional disorders influence nodular thyroid disease is important for organizing prevention strategies. This study investigated the association between thyroid nodules, obesity, diabetes, and dietary habits.

MATERIALS AND METHODS

A cohort of randomly selected adults (455 males, 746 females; age: 18-90 years) living in Palermo (Italy), a mild iodine deficiency area, was cross-sectionally investigated. Participants underwent high-resolution ultrasonographic evaluation of the thyroid, and answered a food frequency questionnaire. Laboratory blood measurements were obtained in 587 participants.

RESULTS AND DISCUSSION

Thyroid nodules were detected in 475 (39.5%) participants. The number of thyroid nodules was correlated with age (r = 0.19; P < 0.001), gender (r = 0.08; P = 0.005), and body mass index (r = 0.07; P = 0.02). No significant correlation was observed between the number of nodules and glycated hemoglobin, serum insulin concentrations, and homeostasis model assessment of insulin resistance. Age-adjusted and gender-adjusted prevalence of both overweight/obesity and type 2 diabetes of each group of participants divided according to the number of nodules significantly increased with the number of nodules (P < 0.05 in both cases). The group of participants with nodules exhibited a significantly lower age-adjusted and gender-adjusted habitual intake of milk (P = 0.02). Multivariate regression analysis showed that age, gender, body mass index, diabetes, and habitual consumption of milk were independently correlated with presence of thyroid nodules.

CONCLUSION

This study seems to indicate that an association exists between obesity, diabetes, and thyroid nodules.

Noninvasive Follicular Thyroid Neoplasms With Papillary-like Nuclear Features Are Genetically and Biologically Similar to Adenomatous Nodules and Distinct From Papillary Thyroid Carcinomas With Extensive Follicular Growth

CONTEXT

- Proposed noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTPs), formerly noninvasive encapsulated papillary carcinoma, follicular variant (PTC-FV), is an indolent tumor with follicular growth and frequent RAS mutations.

OBJECTIVE

- To detect histologic and molecular differences separating NIFTP from follicular adenomas (FAs) and invasive carcinomas, particularly papillary carcinomas with extensive follicular growth (PTC-EFGs) and invasive encapsulated PTC-FV (IE-PTC-FV).

DESIGN

- Sixty-one tumors were reviewed histologically and reclassified into 32 NIFTPs (52%), 4 IE-PTC-FVs (7%), 14 PTC-EFGs (23%), and 11 FAs (18%). Next-generation sequencing for mutations in 50 genes was performed. Clinical outcomes were recorded.

RESULTS

- The NIFTPs and FAs were well circumscribed and unencapsulated. The FAs had bland nuclei, whereas the NIFTPs showed at least 2 of 3 (67%; sufficient) nuclear features (enlargement, irregular contours, chromatin clearing). The IE-PTC-FVs had follicular growth, sufficient nuclear features, and extensive capsular invasion. The PTC-EFGs had a median of 5% papillae with intrathyroidal invasion (broad-based, sclerotic, or small follicle growth patterns); intranuclear pseudoinclusions were present only in PTC-EFGs (9 of 14; 64%). Mutations included RAS in 20 of the 32 NIFTPs (62%), 4 of the 11 FAs (36%), and 3 of the 4 IE-PTC-FVs (75%); BRAF K601E in 1 NIFTP (3%); BRAF V600E in 5 PTC-EFGs (36%). No NIFTPs or FAs recurred or metastasized. All 4 IE-PTC-FVs (100%) had hematogenous metastasis. Two PTC-EFGs (14%) had lymphatic metastasis.

CONCLUSIONS

- The morphologic similarity and RAS mutations in FAs, NIFTPs, and IE-PTC-FVs supports the genetic similarity of those follicular neoplasms in contrast to the unique presence of BRAF V600E mutations in PTC-EFGs. Using strict diagnostic criteria supported by molecular testing, tumors with extensive follicular growth can be classified into follicular type or RAS-like (FA, NIFTP, IE-PTC-FV) versus papillary type or BRAF V600E-like (PTC-EFG).

Encapsulated follicular thyroid tumors of uncertain malignant potential in the new international histological classification

В 2017 г. Международное агентство по изучению рака (МАИР) выпустило в свет новое 4-е издание классификации ВОЗ опухолей эндокринных органов. Как и в предыдущем издании 2004 г., в новой классификации значительное место уделено опухолям щитовидной железы (ЩЖ). Экспертами ВОЗ пересмотрены критерии злокачественности инкапсулированных фолликулярных опухолей с ядрами папиллярного типа. Ранее такие опухоли относили к злокачественным новообразованиям (фолликулярному варианту папиллярного рака), а в новой классификации они получили статус пограничных, или опухолей неопределенного злокачественного потенциала (НЗП). Известно, что оценка злокачественного потенциала фолликулярных новообразований невозможна на этапе дооперационной цитологической диагностики в связи с отсутствием надежных соответствующих признаков. Она затруднена и в 10% случаев фолликулярных опухолей ЩЖ на этапе послеоперационной гистологической диагностики в связи с отсутствием очевидных морфологических проявлений инвазии в собственную капсулу и/или сомнительными для папиллярного рака изменениями ядер опухолевых клеток. В настоящей статье представлены критерии диагностики неинвазивной фолликулярной опухоли ЩЖ с ядрами папиллярного типа, а также еще двух классификационных категорий фолликулярных опухолей НЗП, к которым в соответствии с новой классификацией относятся фолликулярные и высокодифференцированные опухоли ЩЖ НЗП. Особое внимание уделено диагностической значимости инвазивного роста опухоли как основному морфологическому проявлению злокачественности фолликулярных опухолей. В связи с изменившимися критериями морфологической диагностики в статье вынесены на обсуждение вопросы качества гистологической диагностики, которое должно быть неизменно высоким, и влияния изменившейся классификации на лечебную тактику в случаях инкапсулированных фолликулярных опухолей.

[Fine-needle aspiration (FNA) of the thyroid gland : Analysis of discrepancies between cytological and histological diagnoses]

BACKGROUND

Diagnostic problems of thyroid cytology are frequently discussed, but relevance and causes of discrepant cytological and histological diagnoses are rarely studied in detail.

OBJECTIVES

Investigation of causes and relevance of discrepant diagnoses.

MATERIALS AND METHOD

The analysis includes 297 patients who had thyroid resection after prior fine needle aspiration (FNA) and is based on the cytological and histological reports. In special cases, cytological and histological specimens were re-examined.

RESULTS

Malignant tumors were found in 45 patients (15.1 %). In 5 patients the cytological diagnosis was "false negative". Three of these 5 tumors were papillary carcinomas (PTC) of ≤10 mm, one an obviously nonmalignant papillary proliferation of the thyroidal epithelium and one a malignant lymphoma complicating autoimmune thyreoiditis (AIT). In 11 of the 35 patients with a FNA diagnosis "suspicious of malignancy" or "malignant," 1 AIT, 4 goiter nodules, and 6 adenomas were diagnosed histologically. However, since distinct nuclear atypia was found in three of five false positive diagnoses, there still remains doubt in their benignity.

CONCLUSIONS

Carcinomas of ≤10 mm incidentally detected in the resected thyroid tissue may not be relevant to the patient and do not reduce the high negative predictive value of FNA. The final diagnosis on the resected tissue should include the cytological findings. Discrepant findings should be commented in the report to the clinician.

Percutaneous laser ablation for benign thyroid nodules: a meta-analysis

Purpose

To evaluate percutaneous laser ablation in treating benign thyroid nodules, we conducted a meta-analysis based on summarizing existing researches.

Materials and Methods

A literature search for clinical trial was performed in PubMed, Cochrane Library and Excerpt Medica Database. The qualities of included studies were evaluated. We calculated the indexes with mean difference. Heterogeneity and publication bias were tested and explored. We performed subgroup analyses and sensitivity analysis further.

Results

A total of 19 researches and 2137 patients were included in this meta-analysis. The pooled estimates of nodule volume were statistically significant after percutaneous laser ablation for 1 month, 3 month, 6month, 12month, 24month and 36month(P < 0.05). The pooled estimate of thyroid-stimulating hormone was statistically significant after percutaneous laser ablation for 1 and 12 month (P = 0.008 and P = 0.03). The pooled estimate of free triiodothyronine was no statistically significant after percutaneous laser ablation for all follow-up intervals. The pooled estimate of free tetraiodothyronin was statistically significant after percutaneous laser ablation1 month (P = 0.004). The pooled estimate of thyroglobulin was statistically significant after percutaneous laser ablation 24 month (P = 0.04). The heterogeneity was found and the source of heterogeneity was explored in nodule volume for 6 and 12 month. No publication bias was found.

Conclusions

This meta-analysis demonstrated that percutaneous laser ablation was safe and useful in shrinking benign thyroid nodules volume, improving thyroid function, relieving symptoms of pressure and esthetic, especial for hyper-vascular benign thyroid nodules. Larger number of high-quality prospective studies still needs to be performed.

Increased Chromosomal and Oxidative DNA Damage in Patients with Multinodular Goiter and Their Association with Cancer

Thyroid nodules are a common clinical problem worldwide. Although thyroid cancer accounts for a small percentage of thyroid nodules, the majority are benign. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) levels are a marker of oxidative stress and play a key role in the initiation and development of a range of diseases and cancer types. This study evaluates cytokinesis-block micronucleus cytome (CBMN-cyt) assay parameters and plasma 8-OHdG levels and their association with thyroid nodule size and thyroid hormones in patients with multinodular goiter. The study included 32 patients with multinodular goiter and 18 age- and sex-matched healthy controls. CBMN-cyt assay parameters in peripheral blood lymphocytes of patients with multinodular goiter and controls were evaluated, and plasma 8-OHdG levels were measured. The micronucleus (MN) frequency (chromosomal DNA damage), apoptotic and necrotic cells (cytotoxicity), and plasma 8-OHdG levels (oxidative DNA damage) were significantly higher among patients with multinodular goiter. Our study is the first report of increased chromosomal and oxidative DNA damage in patients with multinodular goiter, which may predict an increased risk of thyroid cancer in these patients. MN frequency and plasma 8-OHdG levels may be markers of the carcinogenic potential of multinodular goiters and could be used for early detection of different cancer types, including thyroid cancer.

Association between the KRAS Gene Polymorphisms and Papillary Thyroid Carcinoma in a Chinese Han Population

Several studies have reported the association between MAPK signaling pathway gene polymorphisms and papillary thyroid carcinoma (PTC). KRAS gene, an oncogene from the mammalian RAS gene family plays an important role in the MAPK pathway. This study aimed to identify the potential association of KRAS gene polymorphisms with susceptibility to PTC in a Han Chinese population. A total of 861 patients with PTC, 562 disease controls with nodular goiter and 897 healthy controls were recruited. Four tagSNP polymorphisms (rs12427141, rs712, rs7315339 and rs7960917) of KRAS gene were genotyped by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Statistical analyses and haplotype estimations were conducted using Haploview and Unphased softwares. Only significant differences were observed in genotypic frequencies of the rs7315339 polymorphism (χ² =7.234, df=2, p=0.027) between PTC and disease controls. Statistically significant differences in both allelic and genotypic genotypes frequencies for rs712 (Genotype, χ²=8.258, p=0.016) and rs12427141 (Allele, χ²=3.992, p=0.046; Genotype, χ²=8.140, p=0.017) were observed between PTC patients and controls. Haplotype analyses revealed higher frequencies of GA and TA haplotypes (p=0.039 and p=0.003, respectively) from rs712- rs12427141 (two-SNP) or TGA and TTG haplotype containing the alleles from rs7960917, rs712 and rs12427141, as well as the GAT haplotype containing the alleles from rs712, rs12427141 and rs7315339 in PTC patients than in healthy controls (p=0.042, p=0.037, p=0.027, respectively). Inversely, the haplotype TTA from rs7960917, rs712 and rs12427141 or the haplotype TAC from rs712, rs12427141 and rs7315339 was significantly less frequent in the PTC patients than in normal control (p=0.003, p=0.003, respectively). These findings suggest the role of these KRAS gene variants in susceptibility to PTC. Moreover, significant differences of the KRAS gene polymorphisms may occur between nodular goiter and PTC.

Radiofrequency ablation for treatment of benign thyroid nodules: A PRISMA-compliant systematic review and meta-analysis of outcomes

BACKGROUND

Thyroid nodules (TNs) usually appearing in the general population have the potential possibility of malignant transformation and common problems of jugular oppression such as dyspnea and hoarseness. We performed this meta-analysis to evaluate the efficiency of radiofrequency ablation (RFA) for the treatment of benign TNs in accord with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statements.

METHODS

Published literatures were retrieved from PubMed, Embase, Web of Science, and Scopus up to January 27, 2016. Pooled standard mean difference with 95% confidence interval was estimated by fixed- or random-effects model depending on heterogeneity, which was calculated using the Cochran Q, τ, and I statistics. The quality of the articles was evaluated by the Newcastle-Ottawa scale.

RESULTS

Meta-analysis of data from 1090 patients with 1406 benign TNs in 20 articles showed that with the subgroup stratified by nodule volume, they were significantly decreased at 1, 3, 6, 12, and the last follow-up months, when comparing post-RFA with the initial nodule volume. In addition, the volume also notably declined by cold and hot nodules. By subgrouping into the largest diameter, symptom score, cosmetic score, thyrotropin, triiodothyronine, free thyroxine level, and vascularity, the pooled data indicated that there was a decrease in largest diameter, symptom score, cosmetic score, triiodothyronine level, and vascular scale, an unchanged free thyroxine, and an increased thyrotropin level after RFA. The publication bias for this particular study is presented in the following groups: nodule volume reduction at 6 months and last follow-up month after RFA and symptom score.

CONCLUSION

In summary, by pooling of these studies we recommended that RFA indeed has the advantages in improving outcomes and providing better prognosis for patients with benign TNs.

PREDICTIVE VALUE OF SOMATIC MUTATIONS FOR THE DEVELOPMENT OF MALIGNANCY IN THYROID NODULES BY CYTOPATHOLOGY

OBJECTIVE

The purpose of our prospective longitudinal study was to evaluate the predictive efficacy of genetic testing for malignancies in fine-needle aspiration biopsy samples that are cytologically benign at the time of biopsy.

METHODS

A total of 779 aspirated cytological samples collected from thyroid nodules of 626 patients were included in a 3-year follow-up study. Consecutive patients with cytologically benign thyroid nodules by the Bethesda System for Reporting Thyroid Cytopathology were enrolled in the study. At enrollment, somatic 1-point nucleotide polymorphisms of BRAF and RAS family genes were tested by melting-point analysis, while RET/PTC and PAX8/PPAR-gamma rearrangements were examined by real-time polymerase chain reaction. The genetic test was considered to be positive if a somatic mutation was found. Malignant cytopathologic diagnoses were confirmed by histopathology.

RESULTS

In samples collected from 779 thyroid nodules, there were 39 BRAF, 33 RAS mutations, and 1 RET/PTC rearrangements found at the beginning of the study. No PAX8/PPAR-gamma rearrangement was identified. There were 52 malignant thyroid tumors removed during follow-up, out of which 24 contained a somatic mutation. The specificity of the presence of somatic mutations for malignancies was as high as 93.3%, and sensitivity was 46.2%. The negative predictive value of genetic testing reached 96.0%.

CONCLUSION

Our results show that our set of genetic tests can predict the appearance of malignancy in benign thyroid nodules (at the beginning of follow-up) with high specificity and strong negative predictive value.

ABBREVIATIONS

BRAF = v-raf murine sarcoma viral oncogene homolog B1 FLUS = follicular lesion of undetermined significance FNAB = fine-needle aspiration biopsy FTC = follicular thyroid carcinoma HRAS = homologous to the oncogene from the Harvey rat sarcoma virus KRAS = homologous to the oncogene from the Kirsten rat sarcoma virus NRAS = first isolated from a human neuroblastoma/neuroblastoma RAS = viral oncogene homolog PAX8 = paired box 8 PCR = polymerase chain reaction PPAR-gamma = peroxisome proliferator-activated receptor gamma PTC = papillary thyroid carcinoma RAS = rat sarcoma RET = rearranged during transfection tyrosine-kinase proto-oncogene SM = somatic mutation SNP = single-nucleotide polymorphism.

A focal marked hypoechogenicity within an isoechoic thyroid nodule: is it a focal malignancy or not?

BACKGROUND

A marked hypoechogenicity is a reliable criterion for a malignant nodule, whereas isoechogenicity is considered to be a benign ultrasonographic (US) finding. However, there have been no reports to demonstrate whether a focal marked hypoechogenicity within an isoechoic nodule is a focal malignancy.

PURPOSE

To evaluate whether a focal marked hypoechogenicity within an isoechoic nodule on US examination is a focal malignancy and to correlate US histologic findings using surgical or core needle biopsy (CNB) specimens.

MATERIAL AND METHODS

From January 2010 to August 2011, 28 consecutive patients (25 women, 3 men; mean age, 52.2 years) with 29 thyroid nodules, which showed a focal marked hypoechogenicity within an isoechoic nodule on US, underwent US-guided CNB for a suspicion of a focal malignancy. All nodules were confirmed by surgery (n = 6) or more than two consecutive US-guided biopsies (n = 23). We evaluated the risk of malignancy, and analyzed histological components which correlated with a focal marked hypoechogenic area within an isoechoic nodule on US. Statistical analysis was performed using the Mann-Whitney U test and Fisher's exact test.

RESULTS

Of the 29 nodules, 25 were benign (86.2%) and four were malignant (13.8%). The peripheral location of focal marked hypoechogenicity within an isoechoic nodule was the only significant US finding that suggested malignancy (P = 0.03). All benign focal marked hypoechogenicities were histologically composed of severe fibrosis with a few follicular cells with varying frequencies of hemosiderin, calcification, infarction, and granulation tissue.

CONCLUSION

Although a focal marked hypoechogenicity within an isoechoic nodule is usually benign, the peripheral location of a focal marked hypoechogenicity may be a malignancy. The histologic information obtained by CNB specimen may reduce the needs for repetitive fine needle aspirations or diagnostic surgery.

MicroRNA deep-sequencing reveals master regulators of follicular and papillary thyroid tumors

MicroRNA deregulation could be a crucial event in thyroid carcinogenesis. However, current knowledge is based on studies that have used inherently biased methods. Thus, we aimed to define in an unbiased way a list of deregulated microRNAs in well-differentiated thyroid cancer in order to identify diagnostic and prognostic markers. We performed a microRNA deep-sequencing study using the largest well-differentiated thyroid tumor collection reported to date, comprising 127 molecularly characterized tumors with follicular or papillary patterns of growth and available clinical follow-up data, and 17 normal tissue samples. Furthermore, we integrated microRNA and gene expression data for the same tumors to propose targets for the novel molecules identified. Two main microRNA expression profiles were identified: one common for follicular-pattern tumors, and a second for papillary tumors. Follicular tumors showed a notable overexpression of several members of miR-515 family, and downregulation of the novel microRNA miR-1247. Among papillary tumors, top upregulated microRNAs were miR-146b and the miR-221~222 cluster, while miR-1179 was downregulated. BRAF-positive samples displayed extreme downregulation of miR-7 and -204. The identification of the predicted targets for the novel molecules gave insights into the proliferative potential of the transformed follicular cell. Finally, by integrating clinical follow-up information with microRNA expression, we propose a prediction model for disease relapse based on expression of two miRNAs (miR-192 and let-7a) and several other clinicopathological features. This comprehensive study complements the existing knowledge about deregulated microRNAs in the development of well-differentiated thyroid cancer and identifies novel markers associated with recurrence-free survival.

Next-generation sequencing improves the diagnosis of thyroid FNA specimens with indeterminate cytology

AIMS

The assessment of thyroid nodules is a common clinical challenge. Fine-needle aspiration (FNA) is the standard pre-operative tool for thyroid nodule diagnosis. However, up to 30% of the samples are classified as indeterminate. This often leads to unnecessary surgery. In this study, we evaluated the added value of next-generation sequencing (NGS) for helping in the diagnosis of FNA samples.

METHODS AND RESULTS

We analysed retrospectively 34 indeterminate FNA samples for which surgical resection was performed. DNA was obtained from cell blocks or from stained smears and subjected to NGS to analyse mutations in 50 genes. Mutations in BRAF, NRAS, KRAS and PTEN, that are known to be involved in thyroid cancer biology, were detected in seven FNA samples. The presence of a mutation in these genes was a strong indicator of cancer because five (71%) of the mutation-positive FNA samples had a malignant diagnosis after surgery. Moreover, there was only an 8% cancer risk in nodules with an indeterminate cytological diagnosis but with a negative molecular test.

CONCLUSION

This study demonstrates that thyroid FNA can be analysed successfully by NGS. The detection of mutations known to be involved in thyroid cancer improves the sensitivity of thyroid FNA diagnosis.

Needle track tumor seeding after radiofrequency ablation of a thyroid tumor

A 19-year-old female underwent two radiofrequency ablation procedures for a thyroid tumor that was proven to be nodular hyperplasia versus a follicular neoplasm by fine-needle aspiration. Two years after the last follow-up, the thyroid mass had grown and a newly developed mass was detected in the platysma muscle. After surgery, the thyroid mass was revealed to be a solid papillary thyroid carcinoma, and the subplatysmal mass was tumor seeding.

Proteomics, and metabolomics: magnetic resonance spectroscopy for the presurgical screening of thyroid nodules

We review the progress and state-of-the-art applications of studies in Magnetic Resonance Spectroscopy (MRS) and Imaging as an aid for diagnosis of thyroid lesions of different nature, especially focusing our attention to those lesions that are cytologically undetermined. It appears that the high-resolution of High-Resolution Magic-Angle-Spinning (HRMAS) MRS improves the overall accuracy of the analysis of thyroid lesions to a point that a significant improvement in the diagnosis of cytologically undetermined lesions can be expected. This analysis, in the meantime, allows a more precise comprehension of the alterations in the metabolic pathways induced by the development of the different tumors. Although these results are promising, at the moment, a clinical application of the method to the common workup of thyroid nodules cannot be used, due to both the limitation in the availability of this technology and the wide range of techniques, that are not uniformly used. The coming future will certainly see a wider application of these methods to the clinical practice in patients affected with thyroid nodules and various other neoplastic diseases.

TERT promoter mutation as an early genetic event activating telomerase in follicular thyroid adenoma (FTA) and atypical FTA

BACKGROUND

The telomerase reverse transcriptase (TERT) promoter mutations C228T and C250T have been found in many malignancies, including in thyroid carcinomas. However, it is unclear how early these mutations occur in thyroid tumorigenesis.

METHODS

The study included primary tumors from 58 patients initially diagnosed with follicular thyroid adenoma (FTA), a benign entity, 18 with atypical FTA (AFTA) having an uncertain malignant potential, and 52 with follicular thyroid carcinoma (FTC). Sanger sequencing was used to investigate the mutational status of the TERT promoter. Telomere length and TERT messenger RNA (mRNA) expression were determined using quantitative polymerase chain reaction (PCR). Telomerase activity was assessed using a Telomerase PCR enzyme-linked immunosorbent assay kit.

RESULTS

The C228T mutation was identified in 1 of 58 FTA (2%) and 3 of 18 AFTA (17%) samples. These 4 tumors all expressed TERT mRNA and telomerase activity, whereas the majority of C228T-negative adenomas lacked TERT expression (C228T versus wild-type, P = .008). The C228T mutation was associated with NRAS gene mutations (P = .016). The patient with C228T-mutated FTA later developed a scar recurrence and died of FTC, whereas none of the remaining 57 patients with FTA had recurrence. No recurrence occurred in 3 patients with AFTA who carried C228T during the follow-up period (36-285 months). Nine of the 52 FTCs (17%) exhibited the TERT mutation (8 of 9 C228T and 1 of 9 C250T), and the presence of the mutation was associated with shorter patient survival.

CONCLUSIONS

TERT promoter mutations may occur as an early genetic event in thyroid follicular tumors that have not developed malignant features on routine histopathological workup.

DNA methylation profiling of well-differentiated thyroid cancer uncovers markers of recurrence free survival

Thyroid cancer is a heterogeneous disease with several subtypes characterized by cytological, histological and genetic alterations, but the involvement of epigenetics is not well understood. Here, we investigated the role of aberrant DNA methylation in the development of well-differentiated thyroid tumors. We performed genome-wide DNA methylation profiling in the largest well-differentiated thyroid tumor series reported to date, comprising 83 primary tumors as well as 8 samples of adjacent normal tissue. The epigenetic profiles were closely related to not only tumor histology but also the underlying driver mutation; we found that follicular tumors had higher levels of methylation, which seemed to accumulate in a progressive manner along the tumorigenic process from adenomas to carcinomas. Furthermore, tumors harboring a BRAF or RAS mutation had a larger number of hypo- or hypermethylation events, respectively. The aberrant methylation of several candidate genes potentially related to thyroid carcinogenesis was validated in an independent series of 52 samples. Furthermore, through the integration of methylation and transcriptional expression data, we identified genes whose expression is associated with the methylation status of their promoters. Finally, by integrating clinical follow-up information with methylation levels we propose etoposide-induced 2.4 and Wilms tumor 1 as novel prognostic markers related to recurrence-free survival. This comprehensive study provides insights into the role of DNA methylation in well-differentiated thyroid cancer development and identifies novel markers associated with recurrence-free survival.

Radiofrequency ablation compared to surgery for the treatment of benign thyroid nodules

Objective. Benign thyroid nodules are a common occurrence whose only remedy, in case of symptoms, has always been surgery until the advent of new techniques, such as radiofrequency ablation (RFA). This study aimed at evaluating RFA efficacy, tolerability, and costs and comparing them to hemithyroidectomy for the treatment of benign thyroid nodules. Design and Methods. 37 patients who underwent RFA were retrospectively compared to 74 patients surgically treated, either in a standard inpatient or in a short-stay surgical regimen. Efficacy, tolerability, and costs were compared. The contribution of final pathology was also taken into account. Results. RFA reduced nodular volume by 70% after 12 months and it was an effective method for treating nodule-related clinical problems, but it was not as effective as surgery for the treatment of hot nodules. RFA and surgery were both safe, although RFA had less complications and pain was rare. RFA costed €1,661.50, surgery costed €4,556.30, and short-stay surgery costed €4,139.40 per patient. RFA, however, did not allow for any pathologic analysis of the nodules, which, in 6 patients who had undergone surgery (8%), revealed that the nodules harboured malignant cells. Conclusions. RFA might transform our approach to benign thyroid nodules.

Follicular adenomas exhibit a unique metabolic profile. ¹H NMR studies of thyroid lesions

Thyroid cancer is the most common endocrine malignancy. However, more than 90% of thyroid nodules are benign. It remains unclear whether thyroid carcinoma arises from preexisting benign nodules. Metabolomics can provide valuable and comprehensive information about low molecular weight compounds present in living systems and further our understanding of the biology regulating pathological processes. Herein, we applied ¹H NMR-based metabolic profiling to identify the metabolites present in aqueous tissue extracts of healthy thyroid tissue (H), non-neoplastic nodules (NN), follicular adenomas (FA) and malignant thyroid cancer (TC) as an alternative way of investigating cancer lesions. Multivariate statistical methods provided clear discrimination not only between healthy thyroid tissue and pathological thyroid tissue but also between different types of thyroid lesions. Potential biomarkers common to all thyroid lesions were identified, namely, alanine, methionine, acetone, glutamate, glycine, lactate, tyrosine, phenylalanine and hypoxanthine. Metabolic changes in thyroid cancer were mainly related to osmotic regulators (taurine and scyllo- and myo-inositol), citrate, and amino acids supplying the TCA cycle. Thyroid follicular adenomas were found to display metabolic features of benign non-neoplastic nodules and simultaneously displayed a partial metabolic profile associated with malignancy. This finding allows the discrimination of follicular adenomas from benign non-neoplastic nodules and thyroid cancer with similar accuracy. Moreover, the presented data indicate that follicular adenoma could be an individual stage of thyroid cancer development.

Assessing RET/PTC in thyroid nodule fine-needle aspirates: the FISH point of view

RET/PTC rearrangement and BRAF(V600E) mutation are the two prevalent molecular alterations associated with papillary thyroid carcinoma (PTC), and their identification is increasingly being used as an adjunct to cytology in diagnosing PTC. However, there are caveats associated with the use of the molecular approach in fine-needle aspiration (FNA), particularly for RET/PTC, that should be taken into consideration. It has been claimed that a clonal or sporadic presence of this abnormality in follicular cells can distinguish between malignant and benign nodules. Nevertheless, the most commonly used PCR-based techniques lack the capacity to quantify the number of abnormal cells. Because fluorescence in situ hybridization (FISH) is the most sensitive method for detecting gene rearrangement in a single cell, we compared results from FISH and conventional RT-PCR obtained in FNA of a large cohort of consecutive patients with suspicious nodules and investigated the feasibility of setting a FISH-FNA threshold capable of distinguishing non-clonal from clonal molecular events. For this purpose, a home brew break-apart probe, able to recognize the physical breakage of RET, was designed. While a ≥3% FISH signal for broken RET was sufficient to distinguish nodules with abnormal follicular cells, only samples with a ≥6.8% break-apart FISH signal also exhibited positive RT-PCR results. On histological analysis, all nodules meeting the ≥6.8% threshold proved to be malignant. These data corroborate the power of FISH when compared with RT-PCR in quantifying the presence of RET/PTC in FNA and validate the RT-PCR efficiency in detecting clonal RET/PTC alterations.

Identification of a KEAP1 germline mutation in a family with multinodular goitre

BACKGROUND

The familial clustering of multinodular goitres (MNGs) with a dominant mode of inheritance has been repeatedly reported. Linkage studies have revealed several genetic loci responsible for familial MNG; however, most of the causative variants remain unknown.

METHODS AND RESULTS

Through linkage analysis using single-nucleotide polymorphism markers, we identified a new MNG locus on 19p13.2-q12 in a five-generation Japanese MNG family. Subsequent mutation searches focusing on the candidate 25-Mb region of chromosome 19 identified a heterozygous mutation, c.879_880delinsA, p.Asp294Thr, fs*23, in exon 3 of the KEAP1, which plays a central role in the cytoprotection pathway against oxidative stress. Reverse transcriptase-PCR analysis showed low expression of wild type KEAP1 accompanied by no transcription product of mutant allele in the normal and goitre region of thyroid tissues obtained from the proband. In agreement with previous studies showing that KEAP1 negatively regulates NFE2L2, the NFE2L2 target genes GSTA4 and GCLC were up-regulated in the thyroid tissues of the patient.

CONCLUSIONS

This study identified the first KEAP1 mutation in MNG. The results provide insights into the pathogenesis of goitre which develops in the organ continuously exposed to oxidative stress during hormone synthesis.

Association between the rs2910164 polymorphism in pre-Mir-146a sequence and thyroid carcinogenesis

BACKGROUND

Rs2910164, a Single nucleotide polymorphism (SNP) located in the precursor microRNA sequence of miR-146a, is the only MicroRNA sequence SNP studied in papillary thyroid cancer (PTC). Association studies had been performed in US and UK-Northern European populations, but results were inconsistence. This study evaluated the association between rs2910164 and the risk of PTC as well as benign thyroid tumor (BN), and examined the clinicopathological characteristics of PTC and BN for different genotypes.

METHODS

This case-control study genotyped rs2910164 in 753 PTCs, 484 BNs and 760 controls in a Chinese Han population. Clinicopathological and genetic data were collected and compared. Multivariate logistic regression was performed to calculate adjusted odds ratios (ORs).

RESULTS

There were no differences in rs2910164 genotype distributions between the three groups. PTC cases with three genotypes (CC, CG, GG) had similar clinicopathological characteristics except the existence of "para-cancer" BN (PTC/BN, P = 0.006). PTC/BN patients were older (P = 0.009), and had smaller cancer lesions (P<0.001), lower serum thyrotropin levels (1.82±1.42 vs. 2.21±1.74, P = 0.04), and lower rates of level VI lymph node metastasis (20.8% vs. 52.7%, P<0.001) and lateral neck lymph node metastasis (11.5% vs. 23.0%, P = 0.011) compared with PTC only. Then we supposed a possible progression from BN to PTC which may involve rs2910164 in and performed a multivariate logistic regression analysis of PTC/BN and BN cases to determine risk factors of this progression. Results showed that the rs2910164 GG homozygote (OR = 2.25, 95% CI 1.22-4.14, P = 0.01) was the only risk factor in this study.

CONCLUSION

Rs2910164 was not associated with increased risk of PTC and BN in Chinese patients, but may play a latent role in the transformation from BN to PTC.

The clinical features of papillary thyroid cancer in Hashimoto's thyroiditis patients from an area with a high prevalence of Hashimoto's disease

Background

The goal of this study was to identify the clinicopathological factors of co-existing papillary thyroid cancer (PTC) in patients with Hashimoto’s thyroiditis (HT) and provide information to aid in the diagnosis of such patients.

Methods

This study included 6109 patients treated in a university-based tertiary care cancer hospital over a 3-year period. All of the patients were categorised based on their final diagnosis. Several clinicopathological factors, such as age, gender, nodular size, invasive status, central compartment lymph node metastasis (CLNM) and serum thyroid-stimulating hormone (TSH) level, were compared between the various groups of patients.

Results

There were 653 patients with a final diagnosis of HT. More PTC was found in those with HT (58.3%; 381 of 653) than those without HT (2416 of 5456; 44.3%; p < 0.05). The HT patients with co-occurring PTC were more likely to be younger, be female, have smaller nodules and have higher TSH levels than those without PTC. A multivariate analysis indicated that the presence of HT and higher TSH levels were risk factors for a diagnosis of PTC. In the PTC patients, the presence of HT or another benign nodule was a protective factor for CLNM, whereas no significant association was found for TSH levels.

Conclusion

PTC and HT have a close relationship in this region of highly prevalent HT disease. Based on the results of our study, we hypothesise that long-term HT leads to elevated serum TSH, which is the real risk factor for thyroid cancer.