The meaning and predictivity of Hürthle cells in fine needle aspiration cytology for thyroid nodular disease

Hürthle cell-predominant thyroid fine needle aspiration cytology: A four risk-factor model highly accurate in excluding malignancy and predicting neoplasm

Background

Interpretation of Hürthle cell‐predominant cytologies (HCP) is very challenging as a majority is diagnosed as indeterminate. Prior studies have reported various cytologic features to help distinguish non‐neoplastic (NN) from neoplastic and malignant lesions but had contradicting results. Our aim was to identify risk factors predictive of neoplasm and/or malignancy by correlating cytologic features with clinical and ultrasound findings.

Methods

Sixty‐nine HCP cases with surgical follow‐up were identified, including 35 NN, 20 adenomas, and 14 carcinomas. Ultrasound data were recorded utilizing Thyroid Imaging Reporting and Data System (TI‐RADS) and American Thyroid Association (ATA) scoring systems. Sixteen cytologic criteria were evaluated and semi‐quantitatively scored. Data were assessed by univariable, multivariable and stepwise logistic regression analysis; and statistical significance achieved at P‐value <0.05.

Results

On univariable analysis, significant predictors of neoplasm were high cellularity, isolated single cells, absent colloid, non‐uniform HC population (anisonucleosis), larger nodule size, and higher ATA score. Large‐cell dysplasia and transgressing blood vessels were not found to be significant factors. Multivariable analysis identified a combination of four risk factors (high cellularity, anisonucleosis, absent colloid, and size ≥2.9 cm) that was associated with neoplasm in 10/11 patients. None of 15 patients with zero or 1 out of 4 risk factors had malignancy or neoplasm on follow‐up. This model also significantly outperformed ATA and TI‐RADS scoring systems.

Conclusion

In the absence of four or three risk factors, the model excluded malignancy and neoplasm in all patients. The presence of all four factors predicted neoplasm and malignancy in 91% and 46% of cases, respectively.

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.

Hürthle cell lesions of the thyroid: Progress made and challenges remaining

Hürthle cell-predominant thyroid fine needle aspirations (FNA) are encountered frequently in routine practice, yet they are often challenging to diagnose accurately and are associated with significant interobserver variability. This is largely due to the ubiquity of Hürthle cells in thyroid pathology, ranging from nonneoplastic conditions to aggressive malignancies. Although limitations in cytomorphologic diagnoses likely will remain for the foreseeable future, our knowledge of the molecular pathogenesis of Hürthle cell neoplasia and application of molecular testing to cytologic material have increased dramatically within the past decade. This review provides context behind the challenges in diagnosis of Hürthle cell lesions and summarizes the more recent advances in diagnostic tools.

Malignancy risk for solitary and multiple nodules in Hürthle cell-predominant thyroid fine-needle aspirations: A multi-institutional study

BACKGROUND

Hürthle cell metaplasia is common in hyperplastic nodules, particularly within the setting of lymphocytic thyroiditis (LT). The Bethesda System for Reporting Thyroid Cytopathology indicates that it is acceptable to classify Hürthle cell-predominant fine-needle aspiration (HC FNA) specimens as atypia of undetermined significance (AUS) rather than suspicious for a Hürthle cell neoplasm (HUR) within the setting of multiple nodules or known LT. The goal of the current study was to address whether this approach is justified.

METHODS

HC FNA specimens were identified and correlated with ultrasound and surgical pathology reports if available. Multinodularity was determined based on findings on macroscopic examination if imaging results were unavailable.

RESULTS

A total of 698 HC FNA specimens were identified, including 576 resected nodules, 455 of which (79%) were benign. The overall risk of malignancy for HUR was 27%, whereas the risk of malignancy for AUS was 10%. The mean size of the benign nodules was 2.1 cm on surgical resection specimens, with multiple nodules noted in 293 cases (64%) and histologic LT noted in 116 cases (25%). The mean size of the malignant nodules was 2.8 cm, with multiple nodules and histologic LT noted in 74 cases (61%) and 22 cases (18%), respectively. The malignancy rate did not differ between solitary or multiple nodules (P = .52) or in the presence or absence of LT (P = .12). However, size did significantly differ between malignant and benign nodules (P < 0.01).

CONCLUSIONS

The malignancy rate did not differ significantly in the presence of multiple nodules or LT, although the latter demonstrated a statistical trend. A diagnosis of AUS over HUR based solely on the presence of multinodularity is not warranted.

Cytologic Diagnosis of Oncocytic Neoplasms of the Thyroid Gland: The Importance of the Clinical Scenario

It is a diagnostic challenge to differentiate benign and malignant thyroid neoplasms made up of Hürthle (or oncocytic) cells on cytologic material. They are large, polygonal cells with marked eosinophilic, granular cytoplasm reflective of overly abundant mitochondria. These cells commonly occur in nodular goiters and dominant adenomatous or hyperplastic nodules though they may also be the predominant component of neoplastic lesions. There are significant controversies concerning the optimal management of patients with oncocytic cell carcinoma. This review provides an overview of the most significant studies addressing the distinction between benign and malignant Hürthle cell lesions on cytology and histology.

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

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

Hurthle Cell Lesion: Controversies, Challenges, and Debates

Hurthle cell lesion is one of the most questionable clinico-pathological entities in most of its aspects. Literature has used the terms oncocytic, oxyphilic, Hurthle, and Ashkanazy interchangeably; what does each term denote? Who first described these cells? What is the cell of origin? How much Hurthle cells should be present to define the lesion as Hurthle cell one? Is it possible to differentiate hyperplastic from neoplastic and benign from malignant Hurthle cell lesion on a non-histopathologic ground? Does it belong to follicular or to papillary neoplasms or should it be classified separately? Can we anticipate its clinical behavior or predict its outcome? How can we manage? We will try to answer these questions in light of the ongoing relevant arguments with the aim of resolving some uncertainties and suggesting how to solve others.

Thyroid FNAC containing hürthle cells and hürthle-like cells: A study of 128 cases

Aim:

It is a diagnostic challenge to differentiate benign and malignant cytology in the presence of Hürthle cells. In our previous study, it was determined that in fine needle aspirations (FNA), the malignancy outcome of the Hürthle cells containing group tend to be papillary thyroid carcinoma (PTC) in a higher percentage. The most common misinterpretation is caused by PTC cells with large cytoplasm-like Hürthle cells. The aim of this study is to predict histologic outcome of the nodules, which have Hürthle cells in FNA according to cytological, clinical features, and BRAF^V600E mutation status.

Materials and Methods:

Detailed cytological features of 128 cases were compared with histopathological diagnosis. The analysis of BRAF^V600E mutation of the PTC cases were performed by real-time polymerase chain reaction.

Results:

The neoplastic outcome was increased statistically significantly with younger age (P = 0.020), increase in cellular dyshesion (P = 0.016), presence of nuclear budding (P = 0.046), and granular chromatin (P = 0.003). Nuclear budding (P = 0.014), granular chromatin (P = 0.012), and hypoechoic nodules in ultrasonography (P = 0.011) were significant independent factors for the increase in the malignancy risk. Increased lymphocytes (P= 0.015) and colloid were related to non-neoplastic outcome. According to the surgical outcome, more than half of the malign cases were PTC (74%). BRAF^V600E mutation was detected in 27.8% of the PTC cases.

Conclusion:

PTC cases containing Hürthle cell-like cells may lead to diagnostic errors. Nuclear budding and granular chromatin of Hürthle cells are significant, remarkable findings to predict the outcome of neoplasm and malignancy.

Fine-needle aspiration cytology of thyroid nodules with Hürthle cells: cytomorphologic predictors for neoplasms, improving diagnostic accuracy and overcoming pitfalls

OBJECTIVES

Hürthle cells (HCs) are follicular-derived oncocytic cells seen in a variety of neoplastic and nonneoplastic pathologic entities of the thyroid gland. This study was to report our experience of the surgical outcome on the finding of HCs on fine-needle aspiration biopsies (FNABs) of thyroid nodules, to identify cytologic predictors of HC neoplasms and an attempt to overcome diagnostic pitfalls.

STUDY DESIGN

This was a retrospective study of all FNAB of thyroid nodules with findings of HCs with subsequent surgical resection. The FNAB slides of 70 thyroid nodules were blindly reviewed for specific cytomorphologic characteristics. The cytologic findings were correlated with the corresponding final surgical pathology diagnosis.

RESULTS

The patients ranged in age from 25 to 78 years with a male:female ratio of 1:2. There were 19 false-negative and 4 false-positive cases. Overall high cellularity, scant colloid and >90% HCs on FNAB are consistently seen in a neoplastic HC process. All cases of Hashimoto's thyroiditis were associated with prominent nucleoli and 92% of cases demonstrating transgressing vessels were neoplastic.

CONCLUSION

Diagnostic accuracy can be improved by following the current Bethesda classification system. A constellation of cytomorphologic features in conjunction with clinical findings can be considered a strong predictor of a neoplastic process.

Hürthle cells in fine-needle aspirates of the thyroid: a review of their diagnostic criteria and significance

Although the cytological assessment of Hürthle cell lesions is challenging, the literature offers good, albeit imperfect, guidance to aid in the crucial distinction between nonneoplastic and neoplastic lesions. The significance of a cytologic diagnosis of follicular neoplasm, Hürthle cell type, lies in the rate of malignancy on follow-up surgical excision, ranging in the literature from 10% to 45%. A cytodiagnosis of atypia of undetermined significance (AUS), Hürthle cell type, appears to be associated with a lower risk of malignancy on follow-up than other subtypes of AUS; however, this area warrants further investigation.

Large needle aspiration biopsy histology for preoperative selection of Hürthle cell thyroid nodules

AIMS

To assess whether the large needle aspiration biopsy (LNAB) histological distinction between pure microfollicular nodules and mixed micro-macrofollicular nodules can assist preoperative selection of a Hürthle cell nodule (HCN) discovered by fine needle aspiration cytology (FNAC).

METHODS AND RESULTS

In 24 HCN identified by preoperative FNAC, preoperative LNAB histology was compared with postoperative pathology. FNAC demonstrated seven benign HCN (negative), eight HCN with atypia (positive); seven suspected cancers with HC (positive); and two cancers with Hürthle cells (positive). LNAB showed mixed micro-macrofollicular hyperplastic features in 12 nodules (negative) and a microfollicular structure in 12 nodules (positive), two of which included findings of papillary cancer. Postoperative findings were benign (negative) in 16 patients and malignant (positive) in eight patients. The sensitivity and specificity for FNAC were 87.5% [seven of eight, 95% confidence interval (CI): 47.3-99.7%) and 37.5% (six of 16, 95% CI: 15.2-64.6%], respectively, and for LNAB were 87.5% (seven of eight, 95% CI: 47.3-99.7%) and 68.8% (11 of 16, 95% CI: 41.3-89.0%), respectively. FNAC results were significantly different from postoperative results (McNemar's test, exact two-sided P=0.012), while LNAB results were not (McNemar's test, exact two-sided P=0.219).

CONCLUSIONS

These data suggest that LNAB histology is more accurate than FNAC cytology for the preoperative selection of HCN.

The significance of hurthle cells in thyroid disease

Hürthle cells (HCs) and HC change, along with the frequently employed synonyms "oncocytes/oncocytic change" or "oxyphils/oxyphilic change," are not infrequently described on fine-needle aspiration biopsy (FNAB) reports of thyroid lesions. The description of HCs on FNAB reports may cause significant concern to the clinician; however, placing the finding in the appropriate clinical context may alleviate some anxiety. Not all oxyphilic cells are true HCs and not every aspirate containing HCs is or should be considered equivalent to an HC neoplasm (HCN). There are many benign thyroid lesions associated with HCs or HC change. For clinicians, it may be difficult to discern the significance of these findings and to determine an appropriate course of action. A skilled and experienced cytopathologist is invaluable in discriminating the subtle features that distinguish these lesions from those warranting a more aggressive approach. The diagnosis of HC carcinoma relies on histopathologic scrutiny and evidence of capsular and/or vascular invasion or metastasis to lymph nodes or distant organs. Many investigators have sought clinical, radiographic, cytological, genetic, and other factors to attempt to discriminate preoperatively between benign and malignant HCNs. To date, none have been definitively proven to be reliable. For now, because of the inability to determine the benign or malignant nature of such neoplasms based on cytology alone, a surgical approach is warranted.

The Thyroid Hürthle (Oncocytic) Cell and Its Associated Pathologic Conditions: A Surgical Pathology and Cytopathology Review

Context.—Hürthle cells are eosinophilic, follicular-derived cells that are associated with a variety of nonneoplastic and neoplastic thyroid lesions. The differential diagnosis of Hürthle cell lesions is quite broad.

Objective.—To review the pathologic conditions associated with Hürthle cells in the thyroid and to discuss pathology of thyroid lesions associated with oncocytic cytology.

Data Sources.—A variety of thyroid nonneoplastic (autoimmune thyroiditis, multinodular goiter) and neoplastic conditions (Hürthle cell adenoma, Hürthle cell carcinoma) are associated with Hürthle cell cytology. In addition, there are several thyroid neoplasms that should be considered when one observes a Hürthle cell neoplasm in the thyroid (oncocytic variant of medullary carcinoma, several variants of papillary thyroid carcinoma).

Conclusions.—Oncocytic cytology is seen in a variety of thyroid conditions that are associated with a broad differential diagnosis and care must be used for accurate diagnosis. Newer molecular-based techniques may be useful for further classification of thyroid neoplasms with oncocytic pathology.