The Presence of Hürthle Cells Does Not Increase the Risk of Malignancy in Most Bethesda Categories in Thyroid Fine-Needle Aspirates

The Incidence of Thyroid Cancer in Bethesda III Thyroid Nodules: A Retrospective Analysis at a Single Endocrine Surgery Center

BACKGROUND

Fine-needle aspiration cytology (FNAC) is widely used to diagnose and monitor thyroid nodules. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is the standard for interpreting FNAC specimens. The risk of malignancy in Bethesda III nodules, also known as Atypia of Undetermined Significance (AUS), varies significantly throughout several studies published worldwide. This retrospective study examines the risk of cancer in thyroid FNAC categorized as Bethesda III as identified in the final histopathology of thyroidectomy specimens at a single endocrine surgery center.

METHODS

This retrospective cohort analysis included 1038 consecutive patients who underwent elective thyroid surgery with complete follow-up data between January 2020 and March 2024. Preoperative data on clinical and pathological characteristics have been collected. The final histopathology report from the thyroidectomy specimen was compared to the results of the preoperative FNAC on nodules that were judged to be Bethesda category III. Statistical methods were performed using SPSS version 29.

RESULTS

A total of 670 ultrasound-guided FNACs (64.5%) performed during the study period were included in the final analysis. The study population was predominantly female, represented by 79.6% of patients with a mean age of 42.5 (SD 12.1), while 20.4% were male and significantly older with mean age of 45.13 years (p = 0.02). The FNAC inadequacy rate was 5.1%, which was associated with a high risk of malignancy (6 out of 34; 17.6%). Out of the total sample size of 170 patients classified as group III, 57 were found to have malignancies in final surgical histopathology, representing 33.5% of the cases within this category. The secondary gender-related outcome analysis showed that female patients classified under the Bethesda II category had a significantly higher risk of malignancy, with a rate of 21.2%, compared to males who had a malignancy rate of 3.4% in the same Bethesda category (p = 0.001, chi-square test). However, the female patients exhibited prognostically superior non-invasive tumors compared to male individuals (p = 0.02, chi-square test).

CONCLUSION

This study's results indicate that Bethesda categories II and III are associated with a higher risk of malignancy in comparison to the reports of the first and third editions of the TBSRTC, particularly for female patients classified under category II.

Diagnostic Performance Comparison of Liquid-Based Preparation Methods in Thyroid FNAs

Introduction

Fine needle aspiration (FNA) is recognized worldwide as the primary diagnostic method for evaluating thyroid nodules. Samples collected by FNA can be spread directly onto slides, prepared for cell blocks, or processed as liquid-based cytology. Advocates of the traditional smear technique emphasize that background material such as colloid, cell sequencing characteristics in cell clusters, and cellularity is important in cytological diagnosis. They state that these properties are not observed in liquid-based liquids. Liquid-based cytology techniques aim to provide standardized slides of homogeneous cellular smears with well-preserved cell morphology, producing more precise visualization, shorter interpretation time, and more reproducible results. This study aimed to investigate and compare the diagnostic performance of liquid-based thyroid FNA samples prepared with SurePath and Cytospin over the last 6 years.

Methods

Patients who underwent ultrasound-guided FNA between January 2015 and December 2021 were included in the study. Cytology reports, pathology reports, and demographic information of the patients were collected from the Hospital Information Management System. The programs "SPSS for Windows 21" and "MedCalc Diagnostic Test Evaluation Calculator" were used for data analysis. Chi-square tests were used in crosstab analysis. The Kolmogorov-Smirnov two-sample test, two proportions test, and the confidence interval tests were used to analyze the variables of the methods. P < .05 was considered statistically significant.

Results

The study population comprised 4,855 patients, 83.8% female and 16.2% male. There were no statistical differences in age and gender distribution in the population of both methods. Nondiagnostic outcome rates were 11.2% for SurePath and 12.8% for Cytospin. Sensitivity, specificity, and accuracy values for SurePath and Cytospin methods were determined as 58.57%, 98.28%, and 91.12% and 79.07%, 96.88%, and 94.03%, respectively.

Conclusion

In our study, although the qualitative analytical results were slightly in favor of the cytospin method, we think both ways can be used safely, especially in hospitals where the clinics performing sampling activities are variable and many, as well as in pathology laboratories where the workload is intense.

Preoperative evaluation of thyroid nodules - Diagnosis and management strategies

Thyroid cancer is the most common endocrine malignancy, with increasing incidence over the past few decades. Fine needle aspiration (FNA) biopsy is the gold standard for preoperative diagnosis of thyroid malignancies. Nevertheless, this method renders indeterminate results in up to 30% of the cases. Therefore, these patients are often referred to unnecessary surgery to establish the diagnosis. To improve the accuracy of preoperative diagnosis, several other ways, such as ultrasonography, elastography, immunohistochemical analysis, genetic testing, and core needle biopsy, have been developed and can be used either in association with or as an alternative to FNA. This review aims to evaluate all these diagnostic tools to determine the most appropriate way of managing thyroid nodules and subsequently improve the selection of cases referred to surgery.

Malignancy risk in indeterminate thyroid nodules with Hürthle cells: role of autoimmune thyroiditis

INTRODUCTION

Hürthle cells are modified follicular thyroid cells, whose development and proliferation have been related to different stimuli inducing cellular stress. Most thyroid aspirates containing Hürthle cells are classified as indeterminate, although the specific risk of malignancy for this subtype of atypia remains unclear. The aim of our study was to assess if the presence of Hürthle cells in indeterminate thyroid nodules correlates with the risk of malignancy. We further evaluated if this risk can be modified by the presence of an underlying Hashimoto's thyroiditis.

MATERIALS AND METHODS

We retrospectively analyzed all indeterminate thyroid nodules that were surgically treated at our institution between January 2010 and March 2019. For each nodule, we inferred the presence of Hürthle cells in the cytological report. Cytological findings were then correlated with histological reports.

RESULTS

354 indeterminate thyroid nodules were included in the study. The rate of malignancy resulted significantly lower in nodules exhibiting Hürthle cells compared to those negative for this cellular pattern (11.4% vs 22.5%, p = 0.01). Although there was no difference in the rate of malignancy in the whole population according to the presence or absence of Hashimoto's thyroiditis (21.5 vs 18.5%, p = 0.63), the significantly lower prevalence of malignant lesions in nodules with Hürthle cells was confirmed only in the presence of a histologically documented Hashimoto's thyroiditis (6.2% vs 32%, p = 0.005).

CONCLUSIONS

The finding of Hürthle cells in indeterminate thyroid nodules is associated with a low risk of malignancy in patients with an underlying Hashimoto's thyroiditis. The clinical management of these lesions may therefore be more conservative.

Efficacy and safety of ultrasound-guided microwave ablation versus surgical resection for Bethesda category IV thyroid nodules: A retrospective comparative study

OBJECTIVE

The objective of this study was to assess the efficacy and safety of ultrasound-guided microwave ablation (MWA) for Bethesda IV thyroid nodules and to compare the outcomes, complications, and costs of MWA and thyroidectomy.

METHODS

A total of 130 patients with Bethesda IV nodules were retrospectively reviewed, involving 46 in the MWA group and 84 in the surgery group. The local institutional review board approved this study. Patients in the MWA group were followed up at 1, 3, 6, and 12 months after the intervention. Postoperative complications, treatment time, and cost in the two groups were compared.

RESULTS

Among 84 patients with 85 Bethesda IV nodules in the surgery group, postoperative pathology was benign lesions, borderline tumors, papillary thyroid carcinoma, follicular variant papillary thyroid carcinoma, follicular thyroid carcinoma, and medullary carcinoma in 44, 4, 27, 6, 3, and 1 cases, respectively. Malignant thyroid nodules were more prone to solid echostructure (86.11% vs. 72.72%), hypoechogenicity (55.56% vs. 13.63%), and irregular margin (47.22% vs. 13.63%) than benign lesions. The nodule volume reduction rate of patients at 12 months after MWA was 85.01% ± 10.86%. Recurrence and lymphatic and distant metastases were not reported during the follow-up period. The incidence of complications, treatment time, hospitalization time, incision length, and cost were significantly lower in the MWA group than in the surgery group (all p < 0.001).

CONCLUSIONS

MWA significantly reduces the volume of Bethesda IV nodules with high safety and is recommended for those with surgical contraindications or those who refuse surgical resection. Patients with suspicious ultrasound features for malignancy should be actively treated with surgery.

Hürthle Cell Carcinoma of the Thyroid Gland: Systematic Review and Meta-analysis

INTRODUCTION

Hürthle cell carcinoma (HCC) comprises about 5% of thyroid carcinoma cases. Partly because of its rarity there is much we still need to know about HCC as compared to other histological cancer subtypes.

METHODS

We conducted a systematic literature review following PRISMA guidelines and meta-analysis, from 2000 to 2020, to investigate the main characteristics of HCC and clarify information concerning tumor behavior and treatment.

RESULTS

Our review included data from 9638 patients reported in 27 articles over the past 20 years. This tumor occurred more frequently in women (67.5%). The mean age was 57.6 years, and the mean size of the neoplasm at diagnosis was 30 mm. Extrathyroidal extension was common (24%) but lymph node metastasis was not (9%). Total thyroidectomy was the most common surgical approach, with neck dissection usually performed in cases with clinically apparent positive neck nodes. Radioiodine therapy was frequently applied (54%), although there is no consensus about its benefits. The mean 5- and 10-year overall survival was 91% and 76%, respectively.

CONCLUSION

This review serves to further elucidate the main characteristics of this malignancy. HCC of the thyroid is rare and most often presents with a relatively large nodule, whereas lymph node metastases are rare. Given the rarity of HCC, a consensus on their treatment is needed, as doubts remain concerning the role of specific tumor findings and their influence on management.

The dilemma of 18F-FDG PET/CT thyroid incidentaloma: what we should expect from FNA. A systematic review and meta-analysis

PURPOSE

¹⁸F-FDG thyroid incidentaloma (TI) occurs in ~2% of PET/CT examinations with a cancer prevalence of up to 35-40%. Guidelines recommend fine-needle aspiration cytology (FNA) if a focal ¹⁸F-FDG TI corresponds to a sonographic nodule >1 cm. The aim of this systematic review and meta-analysis was to provide evidence-based data on the diagnostic distribution of ¹⁸F-FDG TIs in the six Bethesda systems for reporting thyroid cytopathology (BETHESDA) subcategories.

METHODS

Original studies reporting ¹⁸F-FDG TIs and cytologically classified according to BETHESDA were included. Six separate meta-analyses were performed to obtain the pooled prevalence (95% confidence interval, 95% CI) of ¹⁸F-FDG TIs in the six BETHESDA subcategories.

RESULTS

Fifteen studies were finally included. Nine studies were from Asian/Eastern and six from Western countries. FNA data according to BETHESDA was available in 2304 cases. The pooled prevalence of ¹⁸F-FDG TIs according to BETHESDA was BETHESDA I 10% (6-14), BETHESDA II 45% (37-53), BETHESDA III 8% (3-13), BETHESDA IV 8% (5-12), BETHESDA V 6% (4-9), BETHESDA VI 19% (13-25). A significantly different prevalence was found in the BETHESDA IV between Asian/Eastern (2%) and Western (19%) studies.

CONCLUSION

Two-thirds of focal ¹⁸F-FDG TIs undergoing FNA have either malignant (BETHESDA VI) or benign (BETHESDA II) cytology while a minority will have indeterminate (BETHESDA III or IV) FNA results. Significant differences between Asian/Eastern and Western studies are also present in the prevalence of indeterminate FNA results.

Atypia of undetermined significance in thyroid cytology: Nuclear atypia and architectural atypia are associated with different molecular alterations and risks of malignancy

BACKGROUND

The Bethesda System for Reporting Thyroid Cytopathology contains an atypia of undetermined significance (AUS) category with heterogeneous and distinct inclusion criteria. The purpose of this study was to investigate differences in malignancy rates and molecular alterations based on the presence of different criteria.

METHODS

A laboratory information search was conducted to identify thyroid fine-needle aspiration specimens signed out as AUS. The cases were reclassified as architectural atypia (3A), cytologic atypia (3C), both architectural and cytologic atypia (3B), or Hürthle cell aspirate (3H). Surgical follow-up and concurrent molecular test results, if available, were collected.

RESULTS

Five hundred ten specimens, including 258 reclassified as 3A, 40 reclassified as 3B, 119 reclassified as 3C, and 86 reclassified as 3H, were identified. The risks of malignancy for the subcategories were 13.4%, 26.3%, 44.1%, and 13.8%, respectively. Additionally, BRAF V600E mutations were more prevalent in specimens with cytologic atypia (3B/3C), whereas low-risk alterations, including KRAS, PTEN, and PAX8-PPARy2, were more prevalent in those with architectural atypia (3A).

CONCLUSIONS

Subdividing AUS specimens on the basis of the type of atypia can yield categories associated with distinct molecular alterations and risks of malignancy.

Thyroid Hürthle Cell Carcinoma: Clinical, Pathological, and Molecular Features

Simple Summary

Hürthle cell carcinoma (HCC) represents 3–4% of thyroid carcinoma cases. It is characterized by its large, granular and eosinophilic cytoplasm, due to an excessive number of mitochondria. Hürthle cells can be identified only after fine needle aspiration cytology biopsy or by histological diagnosis after the surgical operation. Published studies on HCC indicate its putative high aggressiveness. In this article, current knowledge of HCC focusing on clinical features, cytopathological features, genetic changes, as well as pitfalls in diagnosis are reviewed in order to improve clinical management.

Abstract

Hürthle cell carcinoma (HCC) represents 3–4% of thyroid carcinoma cases. It is considered to be more aggressive than non-oncocytic thyroid carcinomas. However, due to its rarity, the pathological characteristics and biological behavior of HCC remain to be elucidated. The Hürthle cell is characterized cytologically as a large cell with abundant eosinophilic, granular cytoplasm, and a large hyperchromatic nucleus with a prominent nucleolus. Cytoplasmic granularity is due to the presence of numerous mitochondria. These mitochondria display packed stacking cristae and are arranged in the center. HCC is more often observed in females in their 50–60s. Preoperative diagnosis is challenging, but indicators of malignancy are male, older age, tumor size > 4 cm, a solid nodule with an irregular border, or the presence of psammoma calcifications according to ultrasound. Thyroid lobectomy alone is sufficient treatment for small, unifocal, intrathyroidal carcinomas, or clinically detectable cervical nodal metastases, but total thyroidectomy is recommended for tumors larger than 4 cm. The effectiveness of radioactive iodine is still debated. Molecular changes involve cellular signaling pathways and mitochondria-related DNA. Current knowledge of Hürthle cell carcinoma, including clinical, pathological, and molecular features, with the aim of improving clinical management, is reviewed.

Molecular alterations in Hürthle cell neoplasms of thyroid: A fine needle aspiration cytology study with cytology-histology correlation

BACKGROUND

Hürthle cell features are frequently observed on the fine-needle aspiration (FNA) cytology of thyroid nodules and often pose a diagnostic challenge because of a significant overlap between cytomorphologic features seen in benign and malignant lesions. Molecular alterations (MAs) associated with these lesions are not well described. The objective of the current study was to evaluate the molecular profile of Hürthle cell lesions classified as Hürthle cell neoplasm (HCN) on cytologic evaluation.

METHODS

The authors retrospectively reviewed their electronic database for cytologic diagnoses of HCN from January 1, 2017 to March 31, 2020.

RESULTS

In total, 279 cases from 275 patients who had a diagnosis of HCN were included in the study. Molecular testing results were available in 85 cases (51 with MAs and 34 without MAs) and, of those, 42 had histologic follow-up available. Eight of 10 malignant cases had MAs, whereas the remaining 2 cases were negative for MAs. The most frequently encountered predominant genetic alterations or classifier findings were chromosome copy number alterations (n = 15), followed by NRAS (n = 8), KRAS (n = 7), suspicious (n = 6), EIF1AX (n = 4), TSHR (n = 3), gene overexpression (n = 3), positive microRNA classifier (n = 2), and 1 each of BRAF K601E, TERT, and HRAS mutations. One hundred thirty-seven cases had histologic follow-up available; of those, 28 were classified as malignant, and 109 were classified as benign (neoplastic and nonneoplastic). The overall risk of malignancy associated with HCN was 20%, and the risk of HCN with MAs was 25%.

CONCLUSIONS

The cytologic diagnosis of HCN includes various MAs without any obvious trend, and most malignant cases (80%) have some type of MA.

Cutaneous thyroid carcinoma sixteen years after benign total thyroidectomy: a unique case

BACKGROUND

Cutaneous metastasis of papillary thyroid carcinoma is rare and is a hallmark of a locally aggressive tumor.

CASE REPORT

We present a unique case of cutaneous thyroid carcinoma sixteen years after total thyroidectomy for multi-nodular goiter. The tumor originated from the upper anterior thoracic wall's skin and was found to invade the rostral half of the sternum's external periosteum and the caudal part of the right sternocleidomastoid muscle. Wide local excision of the neoplasm was performed with macroscopically free margins and right selective neck dissection (lymph node levels IV and V). The skin deficit was reconstructed with a right pectoralis major island flap. The histopathologic findings displayed a papillary thyroid carcinoma with Hürthle cell predominance and microscopically positive margins at the excised portion of the sternocleidomastoid muscle. The patient was placed on close follow-up, and nine months postop, there are no clinical signs of recurrence.

CONCLUSION

To our knowledge, this is the first case of cutaneous thyroid carcinoma following benign thyroidectomy. A possible mechanism for this incidence is the malignant transformation of benign thyroid cells inoculated into the skin. Dissecting along the fascial planes during thyroidectomy and preserving the thyroid capsule establishes a clean surgical field and minimizes the chance of inoculation of thyroid cells into the adjacent structures. Close follow-up and a high level of suspicion for skin lesions in patients with thyroid disease are warranted in all cases. HIPPOKRATIA 2020, 24(2): 88-90.