Diagnostic utility of intracytoplasmic lumen and transgressing vessels in evaluation of Hürthle cell lesions by fine-needle aspiration

Unraveling the Enigma: A Five-Year Comprehensive Analysis of Hurthle Cell Tumors in South India's Tertiary Care Center

BACKGROUND

Hurthle cell tumors of the thyroid gland constitute a rare and enigmatic group of neoplasms, characterized by the presence of Hurthle cells exhibiting abundant eosinophilic cytoplasm and numerous mitochondria. Despite their low incidence, they pose diagnostic challenges and display diverse clinical outcomes. This study aims to provide a comprehensive analysis of the clinicopathological profile of Hurthle cell tumors within a tertiary care center in South India.

METHODS

Through a retrospective approach, we analyzed cases of Hurthle cell tumors diagnosed and treated at a tertiary care center over a five-year period. Clinical, radiological, and histopathological data were meticulously collected and scrutinized. The study focused on examining demographic details, presenting symptoms, imaging features, cytological findings, surgical management, and postoperative outcomes of the patients.

RESULTS

A total of 32 cases of Hurthle cell tumors were identified during the study period. The majority of patients were female (84%), with a mean age of 49.6 years for Hurthle cell carcinoma. Thyroid enlargement and neck mass were the most common presenting complaints. Fine-needle aspiration cytology showed characteristic features suggestive of Hurthle cell tumors in 33% of cases. Total thyroidectomy remains the mainstay surgical approach. Histopathological evaluation confirmed 62.5% of cases as benign adenomas and 37.5% as malignant carcinomas. Among malignant cases, 67% showed capsular invasion and 33% demonstrated vascular invasion. Of the patients, 33.3% received adjuvant radiotherapy. The overall survival rate was 100%. In our study, we found that thyroid nodules larger than 3 cm demonstrated a higher propensity for Hurthle cell carcinoma.

CONCLUSION

Our findings support the multidisciplinary approach in managing Hurthle cell tumors, with a focus on tailored treatment plans for each patient based on individual characteristics. By recognizing the female predominance, assessing nodule size, and employing a combination of thyroidectomy and ablative therapy, clinicians can optimize patient care and contribute to better long-term prognosis and quality of life for those affected by Hurthle cell tumors. Continued research and collaborative efforts are necessary to advance our understanding and refine treatment strategies, paving the way for improved outcomes and enhanced patient management in the future.

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.

Challenges in Cytology Specimens With Hürthle Cells

In fine-needle aspirations (FNA) of thyroid, Hürthle cells can be found in a broad spectrum of lesions, ranging from non-neoplastic conditions to aggressive malignant tumors. Recognize them morphologically, frequently represents a challenging for an adequately diagnosis and are associated with a significant interobserver variability. Although the limitations of the morphologic diagnosis still exist, the interpretation of the context where the cells appear and the recent advances in the molecular knowledge of Hürthle cells tumors are contributing for a more precise diagnosis. This review aims to describe the cytology aspects of all Hürthle cells neoplastic and non-neoplastic thyroid lesions, focusing on the differential diagnosis and reporting according to The Bethesda System for Reporting Thyroid Cytology (TBSRTC). New entities according to the latest World Health Organization (WHO) classification are included, as well as an update of the current molecular data.

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.

Hürthle-cell neoplasms of the thyroid: An algorithmic approach to pathologic diagnosis in light of molecular advances

Our understanding of neoplasia is evolving at a rapid pace in these exciting times, where recent molecular pathology advances are reinforcing and fine tuning morphological divisions and classification. Thyroid gland neoplasia in general, and Hürthle-cell neoplasms in particular, are no exception in the current era of histopathology-molecular biology paradigm. In this review paper, we discuss the rationale that led pathologists in the past to separate Hürthle-cell neoplasms into its own dedicated diagnostic category, and provide an algorithmic approach to the differential diagnosis of oncocytic lesions of the thyroid. This review will also shed light on the current WHO classification of Hürthle-cell neoplasms in light of molecular advances that justify histopathologic distinctions.

Hürthle cell metaplasia in chronic lymphocytic thyroiditis: Role of age factor and review of literature on its molecular pathogenesis

OBJECTIVES

Hürthle cell (HC) metaplasia is an important feature of chronic lymphocytic (Hashimoto) thyroiditis (HT). However, it is rarely observed in juvenile form HT. In a study based on fine needle aspiration cytology, the cytomorphological difference between pediatric HT and its adult form was studied, with special attention on HC metaplasia and its pathogenesis.

MATERIALS AND METHODS

The frequency of following 12 cytomorphological features in 16 pediatric and 104 adult HT cases were compared: follicular cells, lymphoid cells, HCs, plasma cells, lympho-histiocytic aggregates, epithelioid histiocytes, multinucleated giant cells, fire-flare appearance, colloid, intracytoplasmic lumen (ICL) with or without colloid inclusion, paravacuolar granules, and cyst cells. The age decade distribution of HC metaplasia was analyzed.

RESULTS

Significant difference was observed between pediatric HT and its adult form in respect of HC metaplasia and ICL with colloid inclusion in HC. HC were present in 7 (43.8%) of pediatric and 94 (90.4%) of adult HT cases (P = 0.00006). 1 (6.3%) pediatric and 35 (33.7%) adult HT cases had ICL with colloid inclusion in HC (P = 0.03698). As compared to first two decades of life, significantly higher number of cases revealed HC metaplasia in every decade from third decade onwards (P = 0.01290-0.00009); however, the difference in respect of ICL with colloid inclusions attained significance during sixth decade only (P = 0.00235).

CONCLUSIONS

Hürthlization, which appears to be survival response, is rare in pediatric HT and becomes more pronounced starting from third decade onwards; significant increase in ICL with colloid inclusion is a much more delayed phenomenon.

Functional State of Cells During their Life and on their Journey Toward Inactivity and Death: Search for Morphological Evidence in Thyroid Fine Needle Aspiration Smears

Synthesis and storage of thyroglobulin as well as synthesis of thyroid hormones and their release into the circulation are important functions of thyroid, which were studied in fine needle aspiration (FNA) smears from thyroid lesions. Evidence of thyroglobulin synthesis was demonstrated in neoplastic and nonneoplastic follicular cells, especially in Hürthle cells, in the form of colloid inclusions. Whereas the pinocytic vesicles containing colloid at the luminal end of in nonneoplastic and neoplastic follicular cells indicated engulfment of colloid for synthesis of thyroid hormones (T₃ and T₄), the marginal vacuoles (MVs) (fire-flare appearance) at the basal aspects of follicular cells suggested their release on way to the interfollicular capillaries. The morphological evidence of secretary activity could also be demonstrated in medullary thyroid carcinoma (MTC) in the form of azurophilic granules, marginal vacuoles, and intracytoplasmic lumina (ICL) with secretions; the secretory material, likely to be amyloid, present in MTC cells, and their release to the extracellular space was confirmed by positive immunocytochemical staining for calcitonin. It was found that nuclear grooves and related intranuclear cytoplasmic inclusions (INCIs) in papillary thyroid carcinoma (PTC) possibly represent an initial step of a degenerative process leading to formation of inactive cerebriform nuclei. Based on observation regarding formation and release of precursor substances for psammoma bodies (PBs), it was also suggested that PBs may not represent a process of dystrophic calcification over infarcted/dead papillae but suggest an active biological process, which leads to inhibition of growth of neoplastic cells and acts as a barrier against spread of PTC.

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.

Oncocytic lesions of the neuroendocrine system

This paper reviews the pathologic features of lesions which are oncocytic and involve classic endocrine organs. The history of the oncocytic cell, its morphologic and ultrastructural features, and important immunohistochemical findings are reviewed. Oncocytic proliferations including non-neoplastic and neoplastic of the thyroid, parathyroid, adrenal (both cortex and medulla), and pituitary are described. Their clinical relevance, functional capacity and capability, and where appropriate, prognostic implications are discussed. Important and relevant molecular biological information is included where appropriate.

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.

Oncocytic follicular nodules of the thyroid with or without chronic lymphocytic thyroiditis: An institutional experience

BACKGROUND

Oncocytic follicular (OF) cells can be a prominent component of fine needle aspiration (FNA) specimens from neoplasms (adenomas and carcinomas) and nodules arising in multinodular goiter and chronic lymphocytic thyroiditis (CLT). Because OF cells can be present in non-neoplastic and neoplastic thyroid lesions it can be challenging to differentiate between these two in FNA specimens. The aims of this study were to determine the risk of malignancy in cases diagnosed as either oncocytic follicular neoplasm (OFN) or hyperplastic/adenomatoid nodule with OF on FNA and to identify clinicopathologic features that may help in predicting malignancy in such cases, especially the presence or absence of CLT.

DESIGN

We retrospectively searched the computerized laboratory information system at our institution between 1998 and 2009 for thyroid US guided FNA specimens in which the term "oncocytic/oncocytes" was mentioned in the final cytopathologic diagnosis. A total of 340 cases were selected for this study. The following data points were collected: Patient demographics, site of thyroid biopsy, size of lesion, FNA diagnosis, histopathologic follow-up and presence of CLT. Surgical pathology follow-up (SPFU) was available in 269 (79%) cases.

RESULTS

Two hundred and sixty patients were females and 80 males (average age 53 years). The lesion size was <3.0 cm in 241 (71%) and ≥ 3.0 cm in 99 (29%) cases. Cytologic diagnoses included: Follicular neoplasm with oncocytic features (FNOF) 321 and suggestive of FNOF 19 cases; a secondary cytologic diagnosis of CLT was made in 20 cases. SPFU was available in 269 (79%) cases; it was benign in 213 (213/267 = 79%) and malignant in 56 (56/269 = 21%) cases. The background thyroid showed CLT in 67 (25%) cases; 24% (48/196) neoplasms occurred with versus 76% (147/196) without CLT. The rate of malignancy was lower in nodules measuring less than 3.0 cm as compared to those equal or greater than 3.0 cm in size (17% vs. 28% respectively). The presence of CLT did not significantly alter the rate of malignancy in both FNA and surgical pathology specimens.

CONCLUSIONS

Based on this study, nodule size and not CLT appears to be an important clinicopathologic features in the management of thyroid FNA specimens diagnosed as OFN.

Can abundant colloid exclude oncocytic (Hürthle cell) carcinoma in thyroid fine needle aspiration? Cytohistological correlation of 127 oncocytic (Hürthle cell) lesions

OBJECTIVE

The objective of the present study was to find out whether the presence or absence of certain cytological features can exclude oncocytic (Hürthle cell) carcinoma in thyroid fine needle aspiration (FNA) to minimize unnecessary surgery.

METHODS

Over a 17-year period, 127 hypercellular, oncocyte-exclusive, lymphocyte-absent aspirates obtained via ultrasound-guided FNA with on-site assessment had histology slides for review. The presence or absence of six cytological features (microfollicular arrangement, discohesive single cells, small cell dysplasia, large cell dysplasia, transgressing blood vessels and colloid) and one histological feature (macrofollicular component) were determined for each case independently by two cytopathologists.

RESULTS

Histology showed 12 (9.4%) cases of Hashimoto thyroiditis, 23 (18.1%) oncocytic adenomatoid nodules in nodular goitre, 66 (52.0%) oncocytic adenomas and 26 (20.5%) oncocytic carcinomas (13 minimally invasive without angioinvasion, six minimally invasive with angioinvasion, seven widely invasive). Histologically, a macrofollicular component was present in seven of 26 (26.9%) oncocytic carcinomas, including one case with abundant thin colloid. A microfollicular arrangement, discohesive single cells, small cell dysplasia, large cell dysplasia and transgressing vessels were present in oncocytic carcinoma, oncocytic adenoma and oncocytic adenomatoid nodules in nodular goitre.

CONCLUSIONS

A macrofollicular component is frequently present in oncocytic carcinoma, oncocytic adenoma and oncocytic adenomatoid nodules in nodular goitre. None of the cytological features studied, including abundant colloid, can exclude oncocytic carcinoma. Oncocytic carcinoma can only be excluded by thorough histological examination of thyroidectomy specimens. A molecular marker is needed to triage oncocytic lesions in thyroid FNA.

Predictors of Malignancy in Patients with a Thyroid Nodule That Contains Hürthle Cells

Objective. Fine needle aspiration cytology of a thyroid nodule with Hürthle cells can be present in both benign and malignant diseases of the thyroid. The aim of this study was to identify the factors that predict malignancy in patients who underwent thyroidectomy with a preoperative fine needle aspiration cytology that contains a predominance of Hürthle cells.

Study Design. Retrospective data collection.

Setting. Tertiary referral center.

Subjects and Methods. Medical records of 70 consecutive patients were reviewed between March 2005 and August 2010. Predictive factors, as well as age, gender, preoperative serum thyroid-stimulating hormone level, the microscopic findings of fine needle aspiration, ultrasonographic appearance, and size and number of nodules in the pathology report, were correlated with final histopathologic diagnosis of benign or malignant disease.

Results. Patients’ final pathology showed that 21 patients (30%) had malignant disease, of whom 15 patients (71.4%) had papillary carcinoma and 6 patients (28.6%) had Hürthle cell carcinoma. Forty-nine (70%) patients had benign disease (hyperplastic/adenomatoid nodule in 24 patients, Hashimoto thyroiditis in 18 patients, Hürthle cell adenoma in 5 patients, and follicular adenoma in 2 patients). The rate of malignancy was higher in male patients (42.9% vs 28.6%), with nodules measuring ≥2 cm (36.7% vs 25.0%), the presence of a solitary nodule (34.3% vs 27.7%), and the presence of metaplasia in fine needle aspiration (36.4% vs 27.1%), although none was found to be significant ( P > .05).

Conclusion. Thyroid nodules that are reported in cytology as Hürthle cell lesions require surgery to differentiate benign from malignant disease.

Cytomorphological features of Hürthle cell carcinoma: A report of two cases with review of literature

The use of the term “Hürthle cell neoplasm” as the gold standard should be discouraged as it makes evaluating these lesions more confusing. Recently, a number of studies have been conducted to define criteria that are more specific for Hürthle cell carcinoma (HCC). We herein report two cases of HCC of thyroid which were accurately diagnosed preoperatively using various cytological features described in the recent studies. A review of the literature is also presented.

Divide and rule: cytodiagnosis of thyroid lesions using pattern analysis: a study of 233 cases

Fine needle aspiration cytology (FNAC) of the thyroid is a simple, accurate, fast, economical and safe method for the diagnosis of thyroid lesions on FNA. The objective of this study was application of pattern analysis in the interpretation of thyroid lesions. Two hundred and thirty three cases of thyroid lesion were reviewed, which had histopathological correlation. Smears were classified based on primary (predominant) and secondary (next dominant) pattern and categorized. The variation between combined and final cytological diagnosis was correlated with the histopathological diagnosis. The sensitivity, specificity and diagnostic accuracy for the diagnosis of malignancy were 90.47, 100 and 99.14%. Our study demonstrates the feasibility and applicability of pattern analysis in diagnosing thyroid lesions, which could be easily reproducible.

Diagnostic terminology and morphologic criteria for cytologic diagnosis of thyroid lesions: a synopsis of the National Cancer Institute Thyroid Fine-Needle Aspiration State of the Science Conference

The National Cancer Institute (NCI) sponsored the NCI Thyroid Fine-needle Aspiration (FNA) State of the Science Conference on October 22-23, 2007 in Bethesda, MD. The two-day meeting was accompanied by a permanent informational website and several on-line discussion periods between May 1 and December 15, 2007 (http://thyroidfna.cancer.gov). This document summarizes matters regarding diagnostic terminology/classification scheme for thyroid FNA interpretation and cytomorphologic criteria for the diagnosis of various benign and malignant thyroid lesions. (http://thyroidfna.cancer.gov/pages/info/agenda/).

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.

Secretory activity in medullary thyroid carcinoma: A cytomorphological and immunocytochemical study

Medullary thyroid carcinoma (MTC) is a relatively rare thyroid malignancy of C-cell origin that secretes calcitonin. Although its varied cytomorphologic features are well described in literature, very little is mentioned about the morphologic manifestation of its secretory activity. This study, based on nine fine needle aspiration (FNA) samples from eight MTC patients, is an attempt to present the varied cytomorphologic features suggesting secretory activity in MTC as observed in Papanicolaou and MGG stained FNA smears and correlate them with the immunocytochemical (ICC) staining for calcitonin performed on FNA smears and the serum calcitonin values. The average number of cells in these nine samples was as follows: oval/triangular/plasmacytoid (56.7%), small round (23.6%), spindle-shaped (12.7%), and miscellaneous (7.1%). The cytomorphological features suggesting secretory activity, viz., fine cytoplasmic vacuoles, azurophillic granules, marginal vacuoles, and intracytoplasmic lumina (ICL) with secretions were present in eight, eight, five, and six samples, respectively. Material likely to be amyloid, based on morphological features, was present extracellularly in three samples and both intracellularly and extracellularly in six samples. Immunocytochemically, all the nine samples stained for calcitonin and all the three stained for chromogranin showed positive cytoplasmic reaction in the neoplstic cells. The background amyloid (in six samples), the coarse cytoplasmic granules (in two samples), and the contents of ICL (in one sample) were found to be positively stained for calcitonin. The intracytoplasmic secretory material appeared to be diffusing out of some cells both in the routine MGG stained smears and in the smears stained for calcitonin. Histopathology reports of seven samples in six patients confirmed the cytodiagnosis of MTC in all. Baseline serum calcitonin values in three cases and postoperative serum calcitonin levels during follow-up in three others were high. Thus, our study highlighted the morphological manifestations of secretory activity in MTC and the nature of secretory material as calcitonin, supported by immunocytochemical staining and serum calcitonin level.

Fine-needle aspiration biopsy of Hurthle cell lesions of the thyroid gland: A cytomorphologic study of 139 cases with statistical analysis

BACKGROUND

Lesions of the thyroid gland composed of Hurthle cells encompass pathologic entities ranging from hyperplastic nodules with Hurthle cell metaplasia to Hurthle cell carcinomas. The cytologic distinction between these entities can be diagnostically challenging. Many cytologic features of Hurthle cell lesions that distinguish neoplastic Hurthle cell lesions requiring surgery from those that are benign and nonneoplastic have been described, but with variable usefulness. This is due, in part, to the small numbers of cases examined in previous studies and the limited application of statistical analysis. A morphologic study was made of 139 Hurthle cell lesions of the thyroid gland and statistical analysis applied to identify a set of cytomorphologic features that distinguish benign Hurthle cell lesions (BHCL) from Hurthle cell neoplasms (HCN).

METHODS

Fine-needle aspiration biopsies (FNABs) of thyroid nodules with a predominant Hurthle cell component and corresponding histologic followup were included in the study. Cases were divided into BHCL and HCN groups on the basis of the histologic diagnosis. All cases were reviewed to assess the following 14 cytologic features: overall cellularity, cytoarchitecture, percentage of Hurthle cells, percentage of single cells, percentage of follicular cells observed as naked Hurthle cell nuclei, background colloid, chronic inflammation, cystic change, transgressing blood vessels (TBV), intracytoplasmic lumina, presence of multinucleated Hurthle cells, nuclear to cytoplasmic ratio, nuclear pleomorphism/atypia, and nucleolar prominence. The results were evaluated by using univariate and stepwise logistic regression (SLR) analysis; statistical significance was achieved at P-values < 0.05.

RESULTS

One hundred thirty-nine FNAB specimens, corresponding to 56 HCN and 83 BHCL, fulfilled the study criteria. Six of the 14 cytologic features evaluated were shown by univariate analysis to be statistically significant in predicting HCN: nonmacrofollicular architecture (P < 0.001), absence of background colloid (P < 0.001), absence of chronic inflammation (P < 0.001), presence of TBV (P < 0.001), > 90% Hurthle cells (P < 0.001), and >10% single Hurthle cells (P = 0.014). The first four of these features were also shown to be statistically significant in the SLR analysis (P = 0.005, 0.010, 0.016, and 0.045, respectively), and when all four of these features were present HCN was correctly identified 86% of the time.

CONCLUSIONS

In the current study of 139 FNAB specimens of thyroid Hurthle cell nodules, 14 cytologic features were examined and 6 were found to be statistically significant in identifying HCN. The following four features, when found in combination, were found to be highly predictive of HCN: nonmacrofollicular architecture, absence of colloid, absence of inflammation, and presence of TBV.

Cytoplasmic colloid inclusions in thyroid lesions: a cytomorphological study based on fine needle aspiration

INTRODUCTION

Intracytoplasmic lumens (ICL) with or without magenta material and transgressing vessels are features of Hürthle cell neoplasms (HCN). After detection of intracytoplasmic colloid inclusions (CIs) including targetoid (magenta) body-like structures in the Hürthle cells (HC) in a case of Hashimoto's thyroiditis (HT), we reviewed cases of HT, thyroid neoplasms, hyperplastic nodules (HN) and colloid goitres to determine the frequency of these structures. Further, an attempt was made to find out the significance of CIs.

METHODS

FNA smears of 120 HT, 101 colloid goitres, 11 HN, and 76 neoplastic goitres were examined. The presence of CIs and empty ICL were noted in epithelial cells in these lesions. An attempt was made to find out the difference between HT with and without CIs in respect of various cytomorphologic features. The groups were compared using the Fisher's exact test of probability.

RESULTS

The CIs were present in 36 (30.0%) of HT, 26 (34.2%) of neoplastic goitres, 3 (27.3%) of HN, and 4 (4.0%) colloid goitres. As compared to colloid goitres, CIs were present in a significant higher number of cases in HN (P = 0.0202), neoplastic goitres (P < 0.0001), and HT (P < 0.0001). Among neoplasms the frequency of CIs in HCN (75.0%) was significantly higher than that of papillary thyroid carcinoma (PTC) (33.3%, P = 0.0466), and follicular neoplasm (14.3%, P = 0.0083). The CIs were more frequent in HC in HT and HCN but in follicular cells (FC) in other lesions. The HT cases with CIs differed significantly from those without CIs in respect of HC and their cellularity, cellularity of reactive lymphoid cells, extracellular colloid and empty ICL.

CONCLUSION

Care should be taken not to diagnose HT cases with an excessive Hürthle cell component and CIs, and PTC cases with Hürthlization and CIs, as HCN in FNA smears. Based on review of the literature and our findings, it is suggested that the Hürthle cell metaplasia in HT is a survival response of FC and the presence of CIs in Hürthle cell may represent their limited ability to synthesize colloid.

Does the fine-needle aspiration diagnosis of ?H�rthle-cell neoplasm/follicular neoplasm with oncocytic features? denote increased risk of malignancy?

The thyroid fine-needle aspiration (FNA) diagnosis of Hürthle-cell neoplasm (HCN)/follicular neoplasm with oncocytic features (FNOF) does not differentiate between Hürthle-cell adenoma and carcinoma. A majority of cases diagnosed as HCN undergo surgical excision for definite characterization. The aim of this study was to determine the risk of malignancy in cases diagnosed as HCN and identify clinical features that may help in predicting malignancy in patients with FNA diagnosis of HCN. We reviewed a cohort of 206 cases of thyroid FNA diagnosed as HCN; histological follow-up was available in 169 (82%) cases. The cases were evaluated for patient's age, sex, and size of the nodule and histological diagnosis. One hundred and sixty-six were female patients and 40 were male patients (age range, 12-83 yr). The histological diagnoses were benign in 93 (93/169, 55%) cases and malignant in 76 (76/169, 45%) cases. The malignant histological diagnoses were Hürthle-cell carcinoma (HCC), 53 cases; papillary thyroid carcinoma, 19 cases; follicular carcinoma, 3 cases; and medullary carcinoma, 1 case. The risk of malignancy was greater in nodules measuring > or =2 cm (55% vs. 45%; P value < 0.0001) in patients who were > or =40 yr old (82% vs. 18%, P value < 0.0001) than in patients <40 yr. The risk of malignancy was found greater in male patients than in female patients (61% vs. 43%); however, the difference was not statistically significant. The diagnosis HCN/FNOF carries a higher risk of malignancy as compared with a diagnosis of follicular lesion/neoplasm (20% malignancy rate from previously published studies). Clinical features including size of the nodule, age, and possibly sex of the patient can be a part of the decision analysis in selecting a patient for surgery.

Hürthle cell carcinoma is a better gold standard than Hürthle cell neoplasm for fine-needle aspiration of the thyroid: defining more consistent and specific cytologic criteria

BACKGROUND

The majority of fine-needle aspirates of the thyroid that demonstrate a predominance of Hürthle cells are diagnosed as suspicious for Hürthle cell neoplasm. Only a minority of these patients are found to have carcinoma at the time of resection. In the current study, an attempt was made to define criteria that were more specific for Hürthle cell carcinoma without a loss in sensitivity.

METHODS

The literature was reviewed and 33 aspiration samples diagnosed as suspicious for a Hürthle cell neoplasm (4 nonneoplastic cases, 19 adenoma cases, and 10 carcinomas) were reexamined and reclassified based on criteria derived from the literature.

RESULTS

All Hürthle cell carcinomas could be identified using a total of five criteria: predominantly Hürthle cells and scant colloid and at least one of either small cell dysplasia (cytoplasmic diameter less than twice the nuclear diameter, with often quite bland cells), large cell dysplasia (greater than twice the variation in nuclear diameter; large cells typically demonstrate prominent nucleoli and irregular nuclear outlines), crowding (nuclei touching), and dyshesion (single cells). Three of 4 nonneoplastic aspiration samples (75%) and 7 of 19 Hürthle cell adenomas (37%) did not meet these criteria and could reliably be diagnosed as benign.

CONCLUSIONS

By focusing on criteria for Hürthle cell carcinoma rather than all Hürthle cell neoplasms, criteria can be developed that improve the specificity without a loss of sensitivity.