Follicular thyroid neoplasms can be classified as low- and high-risk according to HBME-1 and Galectin-3 expression on liquid-based fine-needle cytology

Are we ready to bridge classification systems? A comprehensive review of different reporting systems in thyroid cytology

The evaluation of thyroid lesions is common in the daily practice of cytology. While the majority of thyroid nodules are benign, in recent decades, there has been increased detection of small and well-differentiated thyroid cancers. Combining ultrasound evaluation with fine-needle aspiration cytology (FNAC) is extremely useful in the management of thyroid nodules. Furthermore, the adoption of specific terminology, introduced by different thyroid reporting systems, has helped effectively communicate thyroid FNAC diagnoses in a clear and understandable way. In 1996, the Papanicolaou Society thyroid cytological classification was introduced. This was followed in 2005 by the first Japanese and then in 2007 by the Bethesda System for Reporting Thyroid Cytopathology, which subsequently underwent two revisions. Other international thyroid terminology classifications include the British, Italian, Australasian and other Japanese cytology systems. This review covers similarities and differences among these cytology classification systems and highlights key points that unify these varied approaches to reporting thyroid FNAC diagnoses.

Update regarding the role of PD-L1 in oncocytic thyroid lesions on cytological samples

AIMS

Several papers have shown that programmed death-ligand 1 (PD-L1) expression is a relevant predictive biomarker in anti-PD-L1 cancer immunotherapy. While its role in several human cancers is correlated with poor prognosis and resistance to anticancer therapies, in thyroid cancers the role of PD-L1 remains questionable. Few articles have studied PD-L1 in thyroid fine-needle aspiration cytology (FNAC), demonstrating a possible correlation with papillary thyroid carcinoma. However, its role in oncocytic thyroid lesions remains controversial. We accordingly examine the performance of PD-L1 immunostaining in liquid based cytology (LBC) from oncocytic lesions.

METHODS

From January 2019 to March 2021, 114 thyroid lesions diagnosed by FNAC from lesions with a predominant oncocytic component, were enrolled for evaluation by PD-L1 immunostaining on both LBC and corresponding histology samples.

RESULTS

The FNAC cohort included 51 benign (B, negative controls), 4 atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS), 57 follicular lesions (follicular neoplasm/suspicious for FN, FN/SFN) and 2 suspicious for malignancy (SFM) cases. Fifty-four cases (11B, 2 AUS/FLUS, 39 FN/SFN and 2 SFM) had histological follow-up including: 1B case resulted as a hyperplastic oxyphilic nodule in Hashimoto thyroiditis (HT), 10B as goitre, 2 AUS/FLUS cases as oncocytic adenomas (OAs); 39 FN/SFN included 27 OAs, 4 FA and 8 oncocytic follicular carcinoma (OFC). The two SFM cases were diagnosed on histopathology as OAs. Increased plasma membrane and cytoplasmic PD-L1 expression were found in 47 cases of the LBC cases (41.2%). Among the histological series, 67.3% of OAs and 75% of OFC had PD-L1 expression, while negative PD-L1 was found in hyperplastic oncocytic cells in HT. A positivity in more than 30% of the neoplastic cells was found in 72.9% of the cases including six OFC.

CONCLUSIONS

These data suggest that PD-L1 expression is expressed in oncocytic thyroid lesions. While weak PD-L1 expression failed to discriminate benign from malignant lesions, OFC demonstrated more intense cytoplasmic and membranous expression.

Systematic Review and Meta-Analysis to Identify the Immunocytochemical Markers Effective in Delineating Benign from Malignant Thyroid Lesions in FNAC Samples

Conventional cytology-based diagnosis for thyroid cancer is limited with more than 30-45% of nodules categorized as indeterminate, necessitating surgery for confirming or refuting the diagnosis. This systematic review and meta-analysis were aimed at identifying immunocytochemical markers effective in delineating benign from malignant thyroid lesions in fine needle aspiration cytology (FNAC) samples, thereby improving the accuracy of cytology diagnosis. A systematic review of relevant articles (2000-2021) from online databases was carried out and the search protocol registered in PROSPERO database (CRD42021229121). The quality of studies was assessed using QUADAS-2. Review Manager 5.4.1 from Cochrane collaboration and MetaDisc Version 1.4 was used to conduct the meta-analysis. Bias in the studies were visually analyzed using funnel plots, and statistical significance was evaluated by Egger's test. Systematic review identified 64 original articles, while meta-analysis in eligible articles (n = 41) identified a panel of 5 markers, Galectin-3, HBME-1, CK-19, CD-56, and TPO. Assessment of the diagnostic performance revealed that Gal-3 (sensitivity: 0.81; CI: 0.79-0.83; specificity: 0.84; CI: 0.82-0.85) and HBME-1 (sensitivity: 0.83; Cl: 0.81-0.86; specificity: 0.85; CI: 0.83-0.86) showed high accuracy in delineating benign from malignant thyroid nodules. Efficacy analysis in indeterminate nodules showed Gal-3 and HBME-1 have high specificity of 0.86 (CI 0.84-0.89) and 0.82 (CI 0.78-0.86), respectively, and low sensitivity of 0.76 (CI 0.72-0.80) and 0.75 (CI 0.70-0.80), respectively. Diagnostic odds ratio (DOR) of Galectin-3 and HBME-1 were 39.18 (CI 23.38-65.65) and 24.44 (CI 11.16-53.54), respectively. Significant publication bias was observed for the markers Galectin-3 and CK-19 (p < 0.05). The panel of 5 markers identified from this meta-analysis are high-confidence candidates that need to be validated in thyroid cytology to establish their efficacy and enable clinical applicability.

Does Locally Advanced Thyroid Cancer Have Different Features? Results from a Single Academic Center

BACKGROUND

Despite the fact that the majority of thyroid cancers are indolent, 15% of patients with well-differentiated carcinoma including papillary thyroid carcinoma (PTC) present with locally advanced thyroid cancer (LATC) at diagnosis. The current study analyzes a cohort of patients with LATC focusing on their risk for local recurrence, distant metastases, and overall survival.

MATERIALS AND METHODS

From January 2010 to December 2020, 65 patients with LATC were retrieved, including 42 cases with preoperative cytological samples. BRAFV600E and TERT mutations were performed on both cytology and histopathology specimens in this cohort.

RESULTS

Among the 65 cases, 42 (65%) were women. The median age was 60.1 years. Histological diagnoses included 25 (38.4%) with classic PTC and 30 (46.1%) aggressive variants of PTC, mostly tall cell variant (17 cases, 26.1%). Multifocality was seen in 33 cases (50.8%). All patients had nodal metastases. The most common site of extrathyroidal extension was the recurrent laryngeal nerve (69.2%). Staging revealed 21 cases were stage I, none were stage II, 33 were stage III, and 7 were stage IVa and 4 stage IVb. No differences were found between well and poorly/undifferentiated thyroid cancers.

CONCLUSION

These data suggest that locally advanced thyroid cancers, including variants of PTC, exhibit a more aggressive biological course and should accordingly be more assertively managed.

Reporting Thyroid Cytology in a Globalized World

The Italian SIAPEC-AIT 2014 classification, the 2017 Bethesda System for Reporting Thyroid Cytology (TBSRTC), the 2016 UK Royal College of Pathologists (RCPath) thyroid reporting system, and the 2019 Japanese reporting system for thyroid aspiration cytology (JRSTAC2019) represent the most widely used reporting systems among clinicians and pathologists for the purpose of cytologically diagnosing, estimating the potential risk of malignancy (ROM), and defining the most appropriate treatment for a patient with a thyroid nodule. Although all the systems use overlapping diagnostic categories and morphologic criteria, they differ on the basis of the criteria for inclusion in the cytologic categories, which may, in turn, affect the ROM of a given category and the clinical management of the patient, particularly with regard to the “indeterminate” categories. The aim of this review is to analyze the main differences that emerge between the systems and to propose possible solutions for a comprehensive reporting system that integrates and harmonizes all the criteria of the Italian classification and the Bethesda system, also taking into account the impact that the new tumor entity NIFTP (non-invasive follicular tumor with papillary-like nuclear features) that has, in many instances, replaced the non-invasive form of the follicular variant of papillary carcinoma, has had on the modification of malignancy risks.

Follicular Epithelial Dysplasia as Hashimoto Thyroiditis-Related Atypia: a Series of 91 Specimens

Follicular epithelial dysplasia (FED) is described as Hashimoto thyroiditis-related atypia and is thought to be a possible precancerous lesion. Dysplasia as an interface between normal state and carcinoma is described in a wide range of diseases and carcinogenesis chains. On the other hand, inflammation-related atypia and cancerogenesis is also widely studied. In this study, we retrospectively analyzed 91 specimens of thyroid gland surgical resections with FED during a 10-year-period at the university hospital pathology department. The study population consisted of 68 females and 15 males aged between 22 and 86 years. The preoperative cytology diagnoses had mainly been in the indeterminate categories with prevailing AUS/FLUS results in the FED-only group (p = 0.005) and suspicious for malignancy and malignant in the group with FED plus adjacent malignancy. The decision for surgery was malignancy related in 48.2% of the cases. The lesions were sized 0.1-3.5 mm and multifocal in 45.1% of the cases. Immunohistochemically, the atypical cells were cyclin D1-positive in 67.5%, galectin-3 in 72.7%, CK19 in 85.7%, and HBME-1 in 87.0% of cases. In conclusion, FED is suggested to be a pathogenetic link between inflammation-related atypia and papillary carcinoma and thus a premalignant precursor of papillary carcinoma in HT as 36.1% of the specimens contained also papillary carcinoma in the present study. Both histopathological nuclear features and the immunoprofile of FED are widely shared with that of papillary carcinoma.

The Role of Cytology in the Diagnosis of Subcentimeter Thyroid Lesions

Thyroid nodules are common and typically detected by palpation and/or ultrasound (US). Guidelines have defined the management of large nodules, but controversy exists regarding nodules ≤ 1 cm. We evaluated a cohort of patients with subcentimeter nodules to determine their rate of malignancy (ROM). A total of 475 thyroid FNAs of lesions ≤ 1 cm with available follow-up were identified from January 2015–December 2019. For comparative analysis, we added a control series of 606 thyroid lesions larger than 1 cm from the same reference period. All aspirates were processed with liquid-based cytology and classified according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Subcentimeter nodules were stratified as 35 category I—non-diagnostic cases (ND; 7.3%), 144 category II—benign lesions (BL; 30.3%), 12 category III—atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS; 2.5%), 12 category IV—follicular neoplasm/suspicious for follicular neoplasm (FN/SFN; 2.5%), 124 category V—suspicious for malignancy (SM; 26.1%), and 148 category VI—positive for malignancy (PM; 31.1%). A total of 307 cases (64.6%) underwent subsequent surgery. Only one ND and three BLs had a malignant outcome. ROM for indeterminate lesions (III + IV) was 3.2%; with 1.6% for category III and 3.2% for category IV. ROM for the malignant categories (V + VI) was 88.2%. The control cohort of lesions demonstrated a higher number of benign histological diagnoses (67.3%). We documented that 57.2% of suspected subcentimeter lesions were malignant, with a minor proportion that belonged in indeterminate categories. There were very few ND samples, suggesting that aspirates of subcentimeter lesions yield satisfactory results. Suspected US features in subcentimeter lesions should be evaluated and followed by an interdisciplinary team for appropriate patient management.

Immunocytochemistry for diagnostic cytopathology-A practical guide

Cytological specimens, which are obtained by minimally invasive methods, are an excellent source of diagnostic material. Sometimes they are the only material available for diagnosis as well as for prognostic/predictive markers. When cytomorphology is not straightforward, ancillary tests may be required for a definitive diagnosis to guide clinical management. Immunocytochemistry (ICC) is the most common and practical ancillary tool used to reach a diagnosis when cytomorphology is equivocal, to differentiate entities with overlapping morphological features, and to determine the cell lineage and the site of origin of a metastatic neoplasm. Numerous immunomarkers are available, and some are expressed in multiple neoplasms. To rule out entities within a differential diagnosis, the use of more than one marker, sometimes panels, is necessary. ICC panels for diagnostic purposes should be customised based on the clinical context and cytomorphology, and the markers should be used judiciously to preserve material for additional tests for targeted therapies in the appropriate setting. This review offers a practical guide for the use of ICC for diagnostic cytopathology, covering the most commonly encountered non-hematolymphoid diagnostic scenarios in various body sites.

How limited molecular testing can also offer diagnostic and prognostic evaluation of thyroid nodules processed with liquid-based cytology: Role of TERT promoter and BRAF V600E mutation analysis

BACKGROUND

Mutational analysis contributes to the diagnosis and prognosis of thyroid nodules analyzed with fine-needle aspiration cytology (FNAC). Although several advanced molecular tests based on multiple molecular markers are available for clinical use and have increased their impact on clinical management of patients, they are not widely available. Among them is BRAF V600E, one of the most studied mutations. Other genetic alterations, such as TERT promoter mutations, may coexist in thyroid carcinomas. Previous studies have demonstrated that this duet might be involved in the aggressiveness of thyroid cancer, although its prognostic value related to mortality remains undefined. The detection of such genetic alterations in thyroid liquid-based cytology (LBC) thus may assist with patient management.

METHODS

From January 2013 to June 2014, 356 thyroid FNAC samples were processed by LBC, including 174 surgical follow-up samples. BRAF V600E and TERT mutation analyses were performed on both LBC and histopathology.

RESULTS

The study included 119 samples categorized as atypia of undetermined significance, 42 categorized as follicular neoplasms, 61 categorized as suspicious for malignancy, and 34 categorized as positive for malignancy. BRAF V600E mutation was detected in 10.4% of all cases, whereas TERT promoter mutations were identified in 1.1%. TERT-mutated cases belonged to the positive for malignancy category, with a histologic diagnosis of tall cell variant of papillary thyroid carcinoma. These genetic alterations correlated with lymph node metastases (P = .0349) and higher disease stage.

CONCLUSIONS

BRAF V600E and TERT analysis can be performed on LBC. TERT mutations are rarely identified in well differentiated thyroid carcinoma but are associated with higher stage. Although a larger molecular panel may offer more information, analyzing these few point mutations is still likely to be useful for managing potentially more aggressive thyroid carcinomas.

The Role of Cell Blocks and Immunohistochemistry in Thyroid Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance Bethesda Category

INTRODUCTION

Thyroid cytology is a widely accepted tool in the clinical triaging of nodular lesions. Cell blocks (CBs) can help in the diagnosis of atypical lesions, namely, thyroid Bethesda category of Atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS).

METHODS

In a series of 224 AUS/FLUS thyroid samples with CB, we studied CB cellularity and feasibility of 3 immunohistochemical markers (cytokeratin 19 [CK19], HBME-1, and galectin-3) apart and in combination.

RESULTS

The CBs were non-diagnostic in 34 cases. Twenty-four CBs contained <10 cells, 45 CBs 10-50 cells, and 121 CBs >50 cells. Notably, more cellularity was found in CBs performed by plasma-thrombin and in-house techniques (p < 0.001). The diagnostic accuracy to detect malignancy was 65.1% for CK19, 72.1% for HBME-1, and 70.3% for galectin-3.

CONCLUSION

In conclusion, CB cellularity is essential for successful immunohistochemistry application and further diagnostic workup of AUS/FLUS cases.

Risk of malignancy in the various categories of the UK Royal College of Pathologists Thy terminology for thyroid FNA cytology: A systematic review and meta-analysis

BACKGROUND

The UK Royal College of Pathologists Thy terminology for reporting thyroid fine-needle aspiration cytology (FNAC), first published in 2009 is used throughout the United Kingdom and Ireland, in some parts of Italy and Switzerland and elsewhere. There is no review of the literature or meta-analysis of the risk of malignancy (ROM) in the various categories of the UK Thy terminology. The goal of this study was to establish the published ROM for each Thy category and compare the results with other existing terminology systems for which similar meta-analyses are available.

METHODS

A comprehensive literature search of online databases was conducted in May 2019 to examine the ROMs for histologically proven nodules with preoperative FNAC classified according to the UK Thy terminology.

RESULTS

Twenty-five articles were identified that showed results of both cytology and histology. Twelve of these articles were excluded to prevent a selection bias because they showed data in just 1 Thy category. In the remaining 13 articles, the pooled ROMs were as follows: Thy1, 12% (95% confidence interval [CI], 5%-22%); Thy2, 5% (95% CI, 3%-9%); Thy3, 22% (95% CI, 18%-26%); Thy3a, 25% (95% CI, 20%-31%); Thy3f, 31% (95% CI, 24%-39%); Thy4, 79% (95% CI, 70%-87%); and Thy5, 98% (95% CI, 97%-99%).

CONCLUSIONS

This meta-analysis shows results comparable to those of meta-analyses of other internationally recognized reporting terminologies for the pooled ROMs for surgically excised nodules in the various Thy reporting categories. There is comparatively little difference (only 6%) between the pooled ROMs of Thy3a and Thy3f surgically excised nodules.

The surgical dilemma of primary surgery for follicular thyroid neoplasms

Follicular thyroid carcinoma is the second most prevalent form of differentiated thyroid carcinoma, following papillary thyroid carcinoma. Preoperative diagnosis is hampered by the fact that fine-needle aspiration cytology as well as supplemental molecular analysis cannot unambiguously distinguish between follicular thyroid carcinoma and benign follicular thyroid adenoma. The 2017 WHO classification defines three histological subtypes of follicular thyroid carcinoma: minimally invasive (excellent prognosis), encapsulated angioinvasive, and widely invasive type (higher risk of recurrence and metastatic spread). The fact that definite characterization of follicular neoplasms is predominantly a postoperative histological diagnosis (core criteria: capsular, vascular and adjacent tissue invasion) translates into the challenge for the thyroid surgeon to plan preoperatively for presence of malignancy and, if required, to adapt the surgical strategy according to intraoperative (frozen section) or postoperative histological findings. Until improved tools for pre-/intraoperative diagnosis are available, the malignant potential of a follicular thyroid lesion can be assessed by stratifying the patient according to clinical risk factors (presence of metastases, advanced patient age, tumor size). A stepwise, escalating surgical approach with restricted primary resection (hemithyroidectomy) and completion surgery based on the definite histopathology is another option to solve this dilemma. The currently recommended surgical treatment strategies for FTCs as published by ATA, BTA, CAEK and ESES are discussed. There is consensus that prophylactic lymphadenectomy is not required for FTCs and that hemithyroidectomy is sufficient in low-risk FTCs (capsular invasion only) whereas thyroidectomy with postoperative radioiodine therapy is indicated in high-risk FTCs (angioinvasion; widely invasive FTC).

Does Radiofrequency Ablation Induce Neoplastic Changes in Benign Thyroid Nodules: A Preliminary Study

BACKGROUND

To evaluate the clinical feasibility of radiofrequency ablation (RFA) of benign thyroid nodules along with cytomorphological alteration, and any malignant transformation through biopsy.

METHODS

The data were retrospectively collected between April 2008 and June 2013 and core needle biopsy (CNB) was performed on 16 benign thyroid nodules previously treated using RFA. The parameters of the patients were compared, between the time of enrollment and the last follow-up examination, using linear mixed model statistical analysis.

RESULTS

No atypical cells or neoplastic transformation were detected in the undertreated peripheral portion of treated benign nodules on the CNB specimen. RFA altered neither the thyroid capsule nor the thyroid tissue adjacent to the treated area. On histopathological examinations, we observed 81.2% acellular hyalinization, which was the most common finding. After a mean follow-up period of over 5 years, the mean volume of thyroid nodule had decreased to 6.4±4.2 mL, with a reduction rate of 81.3%±5.8% (P<0.0001).

CONCLUSION

RFA is a technically feasible treatment method for benign thyroid nodules, with no carcinogenic effect or tissue damage of the normal thyroid tissue adjacent to the RFA-treated zone.

To Obtain More With Less: Cytologic Samples With Ancillary Molecular Techniques-The Useful Role of Liquid-Based Cytology

CONTEXT

- Fine-needle aspiration cytology has been increasingly used as the first tool in the evaluation of several diseases. Although cytology has a relevant role in the discrimination between benign and malignant lesions, conventional slides cannot lead to 100% conclusive results. It was hoped that the introduction of liquid-based cytology (LBC) would improve the efficacy of cytology through standardization, quality improvement, and the possibility of carrying out ancillary techniques on the residual stored material. In recent decades, the application of genomic alterations has been studied on cytologic samples with feasible and reliable results. The molecular analysis offers a powerful aid to define the best clinical or surgical approaches and follow-up for patients. In recent years, the application of different ancillary techniques has been carried out on conventional slides even though LBC represents a useful additional and alternative method for molecular testing.

OBJECTIVE

- To demonstrate the relevance of LBC as a valid aid to overcoming the difficulties encountered in the application of ancillary techniques on conventional slides.

DATA SOURCES

- We examined and reviewed our experience with the application of ancillary techniques on LBC performed on different body sites.

CONCLUSIONS

- We emphasize that LBC achieves significant and accurate results. It represents a valid method for cytologic evaluation and it provides highly reproducible and informative molecular yields.

Role of Immunohistochemistry in Fine Needle Aspiration and Core Needle Biopsy of Thyroid Nodules

Objectives

Immunohistochemistry (IHC) has been used for the diagnosis of indeterminate results in fine needle aspiration (FNA) of thyroid nodules. However, the role of IHC in core needle biopsy (CNB) is not clear and the efficacy of testing for molecular markers following CNB has not been evaluated. The aim of this study is to compare the role of IHC staining in CNB with that in FNA when examining thyroid nodules and to compare the sensitivity and usefulness of different molecular markers.

Methods

Consecutive cases of thyroid FNA and CNB accompanied by IHC from 2004 to 2014 were included in this study with retrospective review of medical record. The rate of remaining nondiagnostic result (unsatisfactory, atypia of undetermined significance or follicular lesion of undetermined significance [AUS/FLUS]) and rate of strong expression of each molecular marker according to the diagnosis were evaluated.

Results

IHC was more frequently performed in CNB with multiple molecular markers compared to FNA (38.1% vs. 2.8%, 3 or 4 markers [Gal-3, HBME-1, CK19, and CD56] vs. 1 marker [Gal-3]). In the CNB group, 11.3% remained as AUS/FLUS after IHC, and the rate remaining nondiagnostic was significantly less than in the FNA group (42.9%). Gal-3 and CK19 showed higher specificity and expressed mainly in conventional type of papillary carcinoma and HBME-1 showed higher sensitivity for the diagnosis of carcinoma with expression in both conventional type and follicular variant papillary thyroid carcinoma.

Conclusion

With these data, we could conclude that IHC was more effective following CNB than following FNA.

The Usefulness of Immunocytochemistry of CD56 in Determining Malignancy from Indeterminate Thyroid Fine-Needle Aspiration Cytology

BACKGROUND

Fine-needle aspiration cytology serves as a safe, economical tool in evaluating thyroid nodules. However, about 30% of the samples are categorized as indeterminate. Hence, many immunocytochemistry markers have been studied, but there has not been a single outstanding marker. We studied the efficacy of CD56 with human bone marrow endothelial cell marker-1 (HBME-1) in diagnosis in the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) category III.

METHODS

We reviewed ThinPrep liquid-based cytology (LBC) samples with Papanicolaou stain from July 1 to December 31, 2016 (2,195 cases) and selected TBSRTC category III cases (n = 363). Twenty-six cases were histologically confirmed as benign (six cases, 23%) or malignant (20 cases, 77%); we stained 26 LBC slides with HBME-1 and CD56 through the cell transfer method. For evaluation of reactivity of immunocytochemistry, we chose atypical follicular cell clusters.

RESULTS

CD56 was not reactive in 18 of 20 cases (90%) of malignant nodules and showed cytoplasmic positivity in five of six cases (83%) of benign nodules. CD56 showed high sensitivity (90.0%) and relatively low specificity (83.3%) in detecting malignancy (p = .004). HBME-1 was reactive in 17 of 20 cases (85%) of malignant nodules and was not reactive in five of six cases (83%) of benign nodules. HBME-1 showed slightly lower sensitivity (85.0%) than CD56. The specificity in detecting malignancy by HBME-1 was similar to that of CD56 (83.3%, p = .008). CD56 and HBME-1 tests combined showed lower sensitivity (75.0% vs 90%) and higher specificity (93.8% vs 83.3%) in detecting malignancy compared to using CD56 alone.

CONCLUSIONS

Using CD56 alone showed relatively low specificity despite high sensitivity for detecting malignancy. Combining CD56 with HBME-1 could increase the specificity. Thus, we suggest that CD56 could be a useful preoperative marker for differential diagnosis of TBSRTC category III samples.

Morphology combined with ancillary techniques: An algorithm approach for thyroid nodules

INTRODUCTION

Several authors have underlined the limits of morphological analysis mostly in the diagnosis of follicular neoplasms (FN). The application of ancillary techniques, including immunocytochemistry (ICC) and molecular testing, contributes to a better definition of the risk of malignancy (ROM) and management of FN. According to literature, the application of models, including the evaluation of ICC, somatic mutations (ie, BRAF^V600E ), micro RNA analysis is proposed for FNs. This study discusses the validation of a diagnostic algorithm in FN with a special focus on the role of morphology then followed by ancillary techniques.

METHODS

From June 2014 to January 2016, we enrolled 37 FNs with histological follow-up. In the same reference period, 20 benign nodules and 20 positive for malignancy were selected as control. ICC, BRAF^V600E mutation and miR-375 were carried out on LBC.

RESULTS

The 37 FNs included 14 atypia of undetermined significance/follicular lesion of undetermined significance and 23 FN. Specifically, atypia of undetermined significance/follicular lesion of undetermined significance resulted in three goitres, 10 follicular adenomas and one NIFTP whereas FN/suspicious for FN by seven follicular adenomas and 16 malignancies (nine non-invasive follicular thyroid neoplasms with papillary-like nuclear features, two invasive follicular variant of papillary thyroid carcinoma [PTC] and five PTC). The 20 positive for malignancy samples included two invasive follicular variant of PTC, 16 PTCs and two medullary carcinomas. The morphological features of BRAF^V600E mutation (nuclear features of PTC and moderate/abundant eosinophilic cytoplasms) were associated with 100% ROM. In the wild type cases, ROM was 83.3% in presence of a concordant positive ICC panel whilst significantly lower (10.5%) in a negative concordant ICC. High expression values of MirR-375 provided 100% ROM.

CONCLUSIONS

The adoption of an algorithm might represent the best choice for the correct diagnosis of FNs. The morphological detection of BRAF^V600E represents the first step for the identification of malignant FNs. A significant reduction of unnecessary thyroidectomies is the goal of this application.

Diagnostic Utility of Molecular and Imaging Biomarkers in Cytological Indeterminate Thyroid Nodules

Indeterminate thyroid cytology (Bethesda III and IV) corresponds to follicular-patterned benign and malignant lesions, which are particularly difficult to differentiate on cytology alone. As ~25% of these nodules harbor malignancy, diagnostic hemithyroidectomy is still custom. However, advanced preoperative diagnostics are rapidly evolving.This review provides an overview of additional molecular and imaging diagnostics for indeterminate thyroid nodules in a preoperative clinical setting, including considerations regarding cost-effectiveness, availability, and feasibility of combining techniques. Addressed diagnostics include gene mutation analysis, microRNA, immunocytochemistry, ultrasonography, elastosonography, computed tomography, sestamibi scintigraphy, [18F]-2-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET), and diffusion-weighted magnetic resonance imaging.The best rule-out tests for malignancy were the Afirma® gene expression classifier and FDG-PET. The most accurate rule-in test was sole BRAF mutation analysis. No diagnostic had both near-perfect sensitivity and specificity, and estimated cost-effectiveness. Molecular techniques are rapidly advancing. However, given the currently available techniques, a multimodality stepwise approach likely offers the most accurate diagnosis, sequentially applying one sensitive rule-out test and one specific rule-in test. Geographical variations in cytology (e.g., Hürthle cell neoplasms) and tumor genetics strongly influence local test performance and clinical utility. Multidisciplinary collaboration and implementation studies can aid the local decision for one or more eligible diagnostics.

Predictive Value of Malignancy of Thyroid Nodule Ultrasound Classification Systems: A Prospective Study

CONTEXT

British Thyroid Association (BTA), American Thyroid Association (ATA), and American Association of Clinical Endocrinologists (AACE/ACE/AME) recommend for thyroid nodules an ultrasound (US)-based stratification of risk of malignancy. Aim of our study was to assess the diagnostic accuracy of US classification systems and their reliability for indication to fine-needle aspiration (FNA).

DESIGN

Prospective study on 987 thyroid nodules consecutively referred for FNA. US images were independently reviewed by four experts for assignment of malignancy risk. Cytologically benign nodules had confirmation with a second FNA, whereas Bethesda class IV, V, and VI nodules were operated upon. Class III nodules had surgery or follow-up on the basis of clinical, immunocytochemical, and US features.

RESULTS

BTA: Malignancy rate was 2.8% in benign, 10.0% in indeterminate, 51.3% in suspicion, and 80.9% in malignant US class. Sensitivity was 0.74, specificity was 0.92, and accuracy was 0.89. ATA: Malignancy rate was 0.0% in benign, 2.2% in very low suspicion, 3.0% in low suspicion, 5.8% in intermediate, and 55.0% in high suspicion US class. Sensitivity was 0.81, specificity was 0.87, and accuracy was 0.86. AACE/ACE/AME: Malignancy rate was 1.1% in low-risk, 4.4% in intermediate-risk, and 54.9% in high-risk US class. Sensitivity was 0.82, specificity was 0.87, and accuracy was 0.86. K correlation coefficient was 78.9%, 76.9%, and 82.0% for BTA, ATA, and AACE/ACE/AME classifications.

CONCLUSIONS

Classification systems had elevated predictive value of malignancy in high-risk classes. ATA and AACE/ACE/AME systems were effective for ruling out indication to FNA in low-US-risk nodules. A similar diagnostic accuracy and a substantial interobserver agreement was provided by the three- and the five-category classifications.

Galectin-3 and HBME-1 Expression on Agarose Cell Blocks from Fine-needle aspirates of Follicular Cell-derived Thyroid Tumors

Aim:

To test the expression of galectin-3 (gal-3) and Hector Battifora mesothelial antigen-1 (HBME-1) on agarose cell blocks (CBs) of fine-needle aspirates aiming to determine their diagnostic value in thyroid follicle cell-derived tumors.

Materials and Methods:

Forty patients with thyroid nodule were enrolled. Fine-needle aspiration biopsy was done and processed to produce smears and CBs. Immune staining was done on CBs using antibodies to gal-3 and HBME-1. Diagnostic value of tests was determined in comparison to pathology.

Results:

Current study included 17 papillary thyroid carcinoma (PTC), 15 follicular adenoma, and 8 follicular thyroid carcinoma (FTC). In PTC diagnosis, co-expression of gal-3/HBME-1 had a sensitivity of 94.1%, specificity of 73.3%, positive predictive value (PPV) of 80%, negative predictive value (NPV) 91.7%, and accuracy of 84.4%. In FTC diagnosis, combined gal-3/HBME-1 expression had a sensitivity of 75%, specificity of 78.6%, PPV of 50%, NPV of 91.7%, and accuracy of 77.8%. Co-expression of gal-3/HBME-1 raised the sensitivity of detection of differentiated thyroid carcinomas from 40% with cytomorphology to 92% and accuracy from 62.5% to 85%.

Conclusion:

The combined immunocytochemical expression of gal-3 and HBME-1 utilizing fine-needle aspirates can improve the sensitivity of detection and diagnostic accuracy of differentiated follicular cell-derived thyroid carcinomas.

The role of fine-needle aspiration in the thyroid nodules of elderly patients

We assess the role of thyroid fine needle aspiration cytology(FNAC) in our series of elderly patients. The growing subset of people aged older than 70 years has shown an increased incidence of thyroid diseases which need to be studied in order to reduce the percentage of surgical treatments in patients with higher likelihood of co-morbidities and associated life risk. We compared Follicular/Indeterminate Neoplasms(FN) and suspicious of malignancy(SM) with pediatric and adult cohorts. We discussed the role of immunocytochemistry-ICC to refine diagnoses. Four hundred and eighty out of 3539FNACs(13.5%) in elderly patients, were surgical followed-up. They included: 35Inadequate, 188benign(BL), 164FN/AUS, 49SM and 44positive for malignancy (PM). All PM and 95.7%BL were histological confirmed. The malignant rate was 24.3% mostly diagnosed as papillary thyroid carcinomas. An ICC panel (HBME-1 and Galectin-3) was carried out on liquid based cytology (LBC) and performed on FN/AUS, SM and PM. We found concordant positive ICC in 69.3%malignancies and concordant negative ICC in 97.6%benign follicular adenomas. Among FNs, 42.9%malignant histologic cases had concordant positivity whilst 97.4%benign histology had negative panel. Thyroid FNAC shows high feasibility in elderly patients. ICC helps in reducing the number of useless thyroidectomies and providing a more adequate clinical and/or surgical selection in elderly patients.

Comparative analysis of diagnostic performance, feasibility and cost of different test-methods for thyroid nodules with indeterminate cytology

Since it is impossible to recognize malignancy at fine needle aspiration (FNA) cytology in indeterminate thyroid nodules, surgery is recommended for all of them. However, cancer rate at final histology is <30%. Many different test-methods have been proposed to increase diagnostic accuracy in such lesions, including Galectin-3-ICC (GAL-3-ICC), BRAF mutation analysis (BRAF), Gene Expression Classifier (GEC) alone and GEC+BRAF, mutation/fusion (M/F) panel, alone, M/F panel+miRNA GEC, and M/F panel by next generation sequencing (NGS), FDG-PET/CT, MIBI-Scan and TSHR mRNA blood assay.We performed systematic reviews and meta-analyses to compare their features, feasibility, diagnostic performance and cost. GEC, GEC+BRAF, M/F panel+miRNA GEC and M/F panel by NGS were the best in ruling-out malignancy (sensitivity = 90%, 89%, 89% and 90% respectively). BRAF and M/F panel alone and by NGS were the best in ruling-in malignancy (specificity = 100%, 93% and 93%). The M/F by NGS showed the highest accuracy (92%) and BRAF the highest diagnostic odds ratio (DOR) (247). GAL-3-ICC performed well as rule-out (sensitivity = 83%) and rule-in test (specificity = 85%), with good accuracy (84%) and high DOR (27) and is one of the cheapest (113 USD) and easiest one to be performed in different clinical settings.In conclusion, the more accurate molecular-based test-methods are still expensive and restricted to few, highly specialized and centralized laboratories. GAL-3-ICC, although limited by some false negatives, represents the most suitable screening test-method to be applied on a large-scale basis in the diagnostic algorithm of indeterminate thyroid lesions.

The role of miRNAs in the evaluation of follicular thyroid neoplasms: an overview of literature

MicroRNA (miRNA) deregulation has been frequently associated with different human cancers. Not only have miRNAs been involved in almost every cellular function but they have also been linked with a significant number of cancers including thyroid carcinomas. Specifically, thyroid tumors encompass several different miRNA profiles based on the histotypes. Furthermore, thyroid lesions with their broad spectrum of neoplasms (from benign to malignant entities) offer the possibility of studying and recognizing specific subsets of different up-and downregulated miRNAs in each different entity. To date, the majority of authors completed their evaluation mostly by including histologic samples of thyroid tumors. Nonetheless, in the last years, a few studies are focusing on the role of miRNA expression in thyroid fine-needle aspiration cytology (FNAC) regardless of the cytologic preparation, including liquid-based cytology. This growing interest is driven by the possible role of miRNAs in the malignant risk stratification, especially for the indeterminate categories of follicular neoplasms (FNs). In this review we overview the reliability of analyzing miRNAs on thyroid lesions, including those diagnosed as FNs, to identify whether their profiles are likely to distinguish benign from malignant lesions, providing a predictive molecular diagnosis on FNAC.

Cytopathology of Follicular Cell Nodules

The detection of thyroid nodules, consisting of different diseases, represents a common finding in population. Their evaluation and diagnosis are mostly achieved with fine-needle aspiration cytology (FNAC). Even though the majority of thyroid nodules are correctly diagnosed, a total of 25% to 30% of them are classified "indeterminate" comprising lesions with varying risk of malignancy and different types of management. Although the number of thyroid FNACs, including small lesions, is increasing due to the reliance upon sonographic and cytologic interpretations, there are issues concerning cytomorphologic interpretation and interobserver reproducibility. Different classification systems have tried to better define the criteria for inclusion in specific categories and to therefore reduce the rate of indeterminate diagnoses such as atypia of undetermined significance, follicular neoplasms, and suspicious for malignancy. However, the support of ancillary techniques (eg, immunocytochemistry and molecular analysis) are reshaping morphologic diagnoses made on materials obtained from FNAC.

The evaluation of miRNAs on thyroid FNAC: the promising role of miR-375 in follicular neoplasms

Fine needle aspiration cytology (FNAC) plays an essential role in the evaluation of thyroid nodules especially for the category of follicular neoplasms (FN) representing 25 % of all thyroid cases including different neoplastic entities. Hence, one of the most promising areas is the application of molecular tests to FNAC. Among them, microRNAs (miRNA),identified as negative (post-transcriptional) gene expression regulators involved in tumor development, are likely to discriminate among FNs. Limited data explored the use of miRNAs on FNAC as well as their role in the malignant risk stratification. We aimed to define whether liquid-based cytology (LBC) is a valid method for miRNA evaluation. From June 2014 to March 2015, we enrolled 27FNs with histological follow-up. In the same reference period, 13 benign nodules (BN) and 20 positive for malignancy (PM) were selected as controls. Histologically, FNs resulted in 14 malignancies (3 papillary thyroid carcinoma-PTC and 11 follicular variant of PTC-FVPC) and 13 follicular adenomas (FA). The 20 PMs included two FVPC, 16 PTC and two medullary thyroid carcinoma (MTC). Five miRNAs (10b, 92a, 221/222 cluster, and 375) were studied on LBC and quantified by real-time PCR. Only miR-375 was over-expressed in the FNs diagnosed as carcinomas and in the PMs. A cut-off of 12 miR-375/U6 relative ratio recognized all BNs and 95 % PMs. Specifically, in each category, FVPCs and PTCs did not show any difference while MTCs had the highest value. miR-375 shows 97.1 % sensitivity, 100 % specificity, 96.3 % negative predictive value (NPV), 100 % positive predictive value (PPV), and 98.3 % diagnostic accuracy. LBC is suitable for miRNAs evaluation. miR-375 resulted over-expressed in all malignant FNs and 95 % PMs. It may represent a valid aid in ruling out BNs and supporting PTCs and/or FVPCs.

Thyroid nodule update on diagnosis and management

Thyroid nodules are common. The clinical importance of thyroid nodules is related to excluding malignancy (4.0 to 6.5% of all thyroid nodules), evaluate their functional status and assess for the presence of pressure symptoms. Incidental thyroid nodules are being diagnosed with increasing frequency in the recent years with the use of newer and highly sensitive imaging techniques. The high prevalence of thyroid nodules necessitates that the clinicians use evidence-based approaches for their assessment and management. New molecular tests have been developed to help with evaluation of malignancy in thyroid nodules. This review addresses advances in thyroid nodule evaluation, and their management considering the current guidelines and supporting evidence.

A Pilot Study of Galectin-3, HBME-1, and p27 Triple Immunostaining Pattern for Diagnosis of Indeterminate Thyroid Nodules in Cytology With Correlation to Histology

Supplemental Digital Content is available in the text.

Indeterminate thyroid nodules form a heterogenous group of lesions that constitute 5% to 30% of thyroid cytology diagnoses. We introduce a triple immunostaining protocol for subtyping. Galectin-3, HBME-1, and p27 triple immunostaining, performed on destained cytology slides and formalin-fixed paraffin-embedded tissue, was developed and applied to 51 patients retrospectively with preoperative cytologic diagnoses of follicular lesion of undetermined significance (n=40), atypia of undetermined significance (n=6), and suspicious for follicular neoplasm (n=5). The malignant rate in this series was 43.1% (22/51). A hierarchal evaluation algorithm was generated based on digital image quantitation of triple-stained histologic sections, and applied to both cytology and histology specimens. Fifty of 51 cytology cases have triple staining validated by internal controls. In cytology specimens, the individual sensitivities and specificities of p27, Galectin3, and HBME1 for cancer with 95% confidence interval are: 86.2% (0.674, 0.955)/66.7% (0.431, 0.845); 77.3% (0.542, 0.913)/72.4% (0.525, 0.866); and 72.7% (0.496, 0.884)/93.1% (0.758, 0.988), respectively. Sensitivity is increased to 95.5% (0.751, 0.998), but specificity is decreased to 69.0% (0.490, 0.840), if Galectin3 and HBME1 are both used in combination as markers for malignancy. However, the level of specificity is increased to 86.2% (0.674, 0.955) and sensitivity remains high 100% (0.808, 1) if in addition, using the Galectin3/HBME1:p27 ratio (ratio ≥2 indicating malignancy) for 2 or 3 markers positive cases. Thus, the triple staining method on cytology slides and histology sections shows a similar sensitivity/specificity/positive predictive value/negative predictive value of 100.0%/86.2%/84.0%/100.0% and 95.5%/86.2%/84.0%/96.2%, respectively (P=0.92). Overall, p27 is the most frequent single positive marker (19/50, 38% in cytology), consistent with benign nature of most indeterminate thyroid nodules. Galectin-3 and HBME-1 colocalization (positive in the same cell) was demonstrated in thyroid cancer in 45.5% (10/22) of histology sections, but in none of the normal thyroid tissues and benign thyroid lesions. This supports the notion that synchronous activation of Galectin-3 and HBME-1 occurs in thyroid malignancy and is highly specific for malignancy. We have demonstrated the performance and pattern of triple immunostaining for subtyping indeterminate thyroid nodules. Further studies and validation in different larger populations are warranted.

The diagnostic and prognostic role of liquid-based cytology: are we ready to monitor therapy and resistance?

Here, we evaluate the diagnostic and prognostic role of liquid-based cytology (LBC) in different body lesions, including thyroid, lung, effusions and malignant breast lesions. LBC has gained consensus after being applied to both non-gynecologic and fine-needle aspiration cytology. Although some remain sceptical regarding the diagnostic efficacy of LBC, mainly when used alone, in recent years, good results have been obtained as long as it showed a high diagnostic accuracy. Here, we discuss the additional possibility of storing material for the application of ancillary techniques (immunocytochemistry-molecular analysis) with several diagnostic and prognostic advantages, which may pave the way for the challenging evaluation of both monitoring responses to treatment and resistance to targeted therapies in thyroid, lung, breast carcinoma or malignant effusions. Furthermore, it provides the use of several molecular spots as specific targets for personalized therapy.

Galectin-3 and HBME-1 improve the accuracy of core biopsy in indeterminate thyroid nodules

Core needle biopsy (CNB) has been recently described as an accurate second-line test in thyroid inconclusive cytology (FNA). Here we retrospectively investigated the potential improvement given by Galectin-3, Cytokeratin-19, and HBME-1 on the accuracy of CNB in thyroid nodules with prior indeterminate FNA report. The study included 74 nodules. At CNB diagnosis, 15 were cancers, 40 were benign, and 19 had uncertain/non-diagnostic CNB report. The above immunohistochemical (IHC) panel was analyzed in all cases. After surgery, 19 malignant and 55 benign lesions were found. All 15 cancers and all 40 benign nodules diagnosed at CNB were confirmed at final histology. Regarding the uncertain CNB group, 4 (21 %) were malignant and 15 (79 %) benign. When we considered all the series, the most accurate IHC combination was Galectin-3 plus HBME-1, while HBME-1 was the most sensitive marker in those nodules with uncertain CNB report. The combination of CNB plus IHC could indentify 19/19 cancers and 53/55 benign lesions. Sensitivity and specificity of CNB increased from 79 to 100 % and from 73 to 96 %, respectively, by adding IHC. CNB can diagnose the majority of thyroid nodules with previous indeterminate FNA cytology, while the accuracy of CNB is increased by adding Galectin-3, Cytokeratin-19, and HBME-1 panel. We suggest to adopt CNB as a second-line approach to indeterminate thyroid FNA, and apply IHC in those lesions with uncertain/non-diagnostic CNB report. This approach should improve the pre-surgical diagnosis of patients. These results should be confirmed in larger prospective series.

DIAGNOSIS OF ENDOCRINE DISEASE: High-yield thyroid fine-needle aspiration cytology: an update focused on ancillary techniques improving its accuracy

Thyroid fine-needle aspiration (FNA) cytology is a fast growing field. One of the most developing areas is represented by molecular tests applied to cytological material. Patients that could benefit the most from these tests are those that have been diagnosed as 'indeterminate' on FNA. They could be better stratified in terms of malignancy risk and thus oriented with more confidence to the appropriate management. Taking in to consideration the need to improve and keep high the yield of thyroid FNA, professionals from various fields (i.e. molecular biologists, endocrinologists, nuclear medicine physicians and radiologists) are refining and fine-tuning their diagnostic instruments. In particular, all these developments aim at increasing the negative predictive value of FNA to improve the selection of patients for diagnostic surgery. These advances involve terminology, the application of next-generation sequencing to thyroid FNA, the use of immunocyto- and histo-chemistry, the development of new sampling techniques and the increasing use of nuclear medicine as well as molecular imaging in the management of patients with a thyroid nodule. Herein, we review the recent advances in thyroid FNA cytology that could be of interest to the 'thyroid-care' community, with particular focus on the indeterminate diagnostic category.

Diagnostic significance of elevated expression of HBME-1 in papillary thyroid carcinoma

This study examined the association between hector battifora mesothelial antigen-1 (HBME-1) expression and papillary thyroid carcinoma (PTC). A total of 206 patients were enrolled in the current study including 96 PTC patients and 110 patients with benign thyroid nodules (BTN). Immunohistochemistry (Envision) were performed to assess the expression of HBME-1. Receiver operating characteristic curve (ROC) curves were applied to evaluate the diagnostic tumor node metastasis (TNM) value of HBME-1. Specimens from 96 patients with PTC and 110 patients with BTC were reviewed. HBME-1 was positively immunostained in PTC tissue, which was significantly higher than that in BTN tissues (77.1 vs. 5.77 %, P < 0.05). Immunohistochemistry also identified that HBME-1 expression did not show any statistically significant differences based on gender, age, tumor size, TNM stage, and lymph node metastasis (P > 0.05). Importantly, HBME-1 expression was correlated with infiltration levels and differential levels in PTC (both P < 0.05). HBME-1 was found to have high sensitivity (94.5 %) and specificity (77.08 %) for PTC diagnosis. Moreover, HBME-1 had a high specificity (83.33 %) at identifying the differential levels of PTC, but a low sensitivity (22.92 %). The sensitivity and specificity of HBME-1 identifying the infiltration levels of PTC were, respectively, 72.70 and 72.00 %. HBME-1 was highly expressed in PTC tissues, and HBME-1 can serve as a potential biomarker in the diagnosis of PTC.

2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the American Thyroid Association's (ATA's) guidelines for the management of these disorders were revised in 2009, significant scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles on adults were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations for therapeutic interventions. We developed a similarly formatted system to appraise the quality of such studies and resultant recommendations. The guideline panel had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, use of molecular markers, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to screening for thyroid cancer, staging and risk assessment, surgical management, radioiodine remnant ablation and therapy, and thyrotropin suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using imaging and serum thyroglobulin, thyroid hormone therapy, management of recurrent and metastatic disease, consideration for clinical trials and targeted therapy, as well as directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

Cytopathology of Follicular Cell Nodules

This article corresponds to a lecture delivered during the Endocrine Pathology Society symposium held in Boston on 21 March 2015 (104th USCAP meeting, March 21-27). It focuses on the importance of cytopathology in endocrine thyroid pathology and the limits and pitfalls of diagnosis in follicular cell lesions. Lights and shadows are present in each diagnostic technique: Fine needle aspiration has imposed itself as a gold standard in thyroid nodules thanks to its easiness of execution and high cost-effectiveness ratio. A milestone in this field is represented by the National Cancer Institute (NCI) Thyroid Fine Needle Aspiration (FNA) State of the State of the Science Conference hosted in October 22-23, 2007 by the NCI, followed by a series of documents published in Diagnostic Cytopathology and Cytojournal (2008) as well as in an atlas entitled: The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC): terminology and criteria (2010, Springer). "Gray" zones still remain, causing difficulties and anxiety to the cytopathologist when facing challenging cases. Each diagnostic category of TBSRTC is analyzed and discussed in a concise fashion with special emphasis on challenging cases such as atypia of undetermined significance (AUS), suspicion for follicular neoplasms (SFNs), diagnoses of papillary thyroid carcinoma (PTC) in Hashimoto thyroiditis and follicular variant of papillary carcinoma (FVPTC). Our aim was to better define and clarify the spectrum of follicular cell lesions in thyroid nodule samplings and to underline the diagnostic limits in order to avoid pitfalls. New emerging molecular biology techniques may represent useful tools in selected morphological challenging cases and lead to new therapeutic approaches in line with drug-tailored therapy and personalized medicine.

The Role of CD56 in Thyroid Fine Needle Aspiration Cytology: A Pilot Study Performed on Liquid Based Cytology

Background

Fine needle aspiration Cytology (FNAC) fulfills a reliable role in the evaluation of thyroid lesions. Although the majority of nodules are quite easily diagnosed as benign or malignant, 30% of them represent an indeterminate category whereby the application of ancillary techniques (i.e. immunocytochemistry-ICC and molecular testing) has been encouraged. The search for a specific immunomarker of malignancy sheds light on a huge number of ICC stains although none of them attempt to yield 100% conclusive results. Our aim was to define in a pilot study on thyroid FNAC whether CD56 might be a valid marker also in comparison with HBME-1 and Galectin-3.

Materials and Methods

Inasmuch as this is the largest pilot study using only liquid based cytology (LBC), we selected all the cases only in the categories of benign nodules (BN) and positive for malignancy (PM) for validation purposes. Eighty-five consecutive (including 50 PM and 35 BN) out of 950 thyroid FNACs had surgical follow-up. The ICC panel (HBME-1, Galectin-3 and CD56) was carried out on LBC and histology.

Results

All BNs and PMs were histological confirmed. CD56 was negative in 96% of the PM while 68.5% of the BNs showed cytoplasmic positivity for this marker, with an overall high sensitivity (96%) but lower specificity (69%). In specific, our 96% of the PMs did not show any follicular cell with CD56 expression. Different ICC combinations were evaluated showing that the panel made up of CD56 plus HBME-1 and Galectin-3 had the highest sensitivity (98%) and specificity (86%).

Conclusions

Our pilot study suggests that CD56 may be a good marker for ruling out PTC and its variants. The low specificity suggests that an immunopanel including also HBME-1 and Galectin-3 could obtain the highest diagnostic accuracy in thyroid lesions. Our results suggest that CD56 may be a feasible additional marker for identifying malignancies also in the FNs and SMs.

Surgical and Pathological Changes after Radiofrequency Ablation of Thyroid Nodules

Background. Radiofrequency ablation (RFA) has been recently advocated as an effective technique for the treatment of symptomatic benign thyroid nodules. It is not known to what extent it may affect any subsequent thyroid surgery and/or histological diagnosis. Materials and Methods. RFA was performed on 64 symptomatic Thy2 nodules (benign nodules) and 6 symptomatic Thy3 nodules (follicular lesions/follicular neoplasms). Two Thy3 nodules regrew after the procedure, and these patients accepted to undergo a total thyroidectomy. Here we present how RFA has affected the operation and the final pathological features of the surgically removed nodules. Results and Conclusions. RFA is effective for the treatment of Thy2 nodules, but it should not be recommended as first-line therapy for the treatment of Thy3 nodules (irrespective of their mutational status), as it delays surgery in case of malignancy. Moreover, it is unknown whether RFA might promote residual tumor progression or neoplastic progression of Thy3 lesions. Nevertheless, here we show for the first time that one session of RFA does not affect subsequent thyroid surgery and/or histological diagnosis.

The potential of liquid-based cytology in lymph node cytological evaluation: the role of morphology and the aid of ancillary techniques

OBJECTIVES

Our aim was to evaluate the feasibility and diagnostic accuracy of liquid-based cytology (LBC) on lymph node fine needle aspiration (FNA). FNA may fulfil a challenging role in the evaluation of the majority of primary (benign and malignant) diagnoses as well as metastatic lymph node lesions. Although the morphological features may be quite easily recognized, cytological samples with a scant cellular component may raise some issues.

METHODS

We appraised 263 cytological lymph nodes from different body regions analysed between January and December 2013, including 137 male and 126 female patients, and processed with LBC.

RESULTS

The cytological diagnoses included 160 benign and 103 malignant lesions. We reported 35 benign and 73 malignant lesions from 108 with surgical follow-up. The latter malignant series included 68 metastatic lesions, four suspicious for malignancy and one inadequate sample. The cytological diagnoses were supported by 62 conclusive immunocytochemical and 28 molecular analyses. Of the 108 cases, we documented 35 true negatives, 72 true positives, one false negative and no false positives, resulting in 98.6% sensitivity, 100% specificity, 99% diagnostic accuracy, 97.2% negative predictive value and 100% positive predictive value.

CONCLUSIONS

FNA represents the first diagnostic tool in lymph node management and a reliable approach in order to avoid an excision biopsy. Furthermore, LBC is a feasible method for ancillary tests for which methanol-fixed samples are suitable, such as immunocytochemistry and molecular analysis.

Immunohistochemical Diagnosis of Thyroid Tumors

Recent insight into the molecular mechanisms of thyroid carcinogenesis has led to studies involving newly directed antibodies. With the introduction of new molecular targeted therapies, these antibodies may represent useful predictors of therapeutic response in tumors unresponsive to radioiodine or insensitive to conventional antitumor therapies. These markers complement the development of markers that are able to discern benign from malignant entities, including hyalinizing trabecular tumors, oncocytic neoplasms, and follicular variant of papillary thyroid carcinoma. The use of antibodies directed to proteins generated by mutated genes may represent a cost-effective method for diagnosing and managing patients affected by thyroid tumors.

Malignancy rate of thyroid nodules defined as follicular lesion of undetermined significance and atypia of undetermined significance in thyroid cytopathology and its relation with ultrasonographic features

Fine-needle aspiration biopsy (FNAB) has been widely accepted as the most accurate, safe, and cost-effective method for evaluation of thyroid nodules. The most challenging category in FNAB is atypia of undetermined significance (AUS) and follicular lesion of undetermined significance (FLUS). The Bethesda system (BS) recommends repeat FNAB in that category due to its low risk of malignancy. In our study, we aimed to investigate the malignancy rate of thyroid nodules of AUS and FLUS and whether there were different malignancy rates among the different patterns in this category, and to evaluate the presence of biochemical, clinical, and echographic features possibly predictive of malignancy related to AUS and FLUS. Data of 268 patients operated for AUS and FLUS cytology were screened retrospectively. Ultrasonographic features and thyroid function tests, thyroid antibodies, scintigraphy, and histopathological results were evaluated. Of the 268 patients' results, 276 nodules are evaluated. Malignancy rates were 24.3 % in the AUS group, 19.8 % in the FLUS group, and 22.8 % in both groups. In the evaluation of all nodules, the predictive features of malignancy are hypoechogenicity and peripheral vascularization of the nodule. We determined that the malignancy rates in these nodules are higher than that in the literature rate. This high ratio may be due to the fact that we studied only patients who underwent surgery. The ultrasonographic features alone may be insufficient to predict the malignancy; therefore, all the clinical and ultrasonographic features must be considered in the evaluation of the thyroid nodules. In addition, we think that the recommended management of repeat FNAB in these groups must be reconsidered with the clinical and ultrasonographic features.

Follicular variant of papillary thyroid carcinoma: accuracy of FNA diagnosis and implications for patient management

Follicular variant of papillary thyroid carcinoma (FVPTC) creates a continuous diagnostic dilemma among pathologists because of the paucity of nuclear changes of papillary carcinoma and overlapping features with benign and other neoplastic follicular lesions. Current guidelines for the management of thyroid nodules recommend surgery for confirmed PTC, suspicious for PTC, and follicular neoplasm cases, while further immediate diagnostic studies or treatment are not routinely required if the nodule is benign on cytology. This study is designed to determine the accuracy of cytology in the diagnosis of FVPTC, based on the Bethesda classification system, and determine the implications for patient management based on the current recommendation. Based on a retrospective review of cytologic diagnoses between January 2008 and December 2011, thyroid fine needle aspiration (FNA) cytology specimens with subsequent surgical intervention and a final diagnosis of FVPTC were selected. The cytologic diagnoses were compared with the final diagnoses, and the percentage of cases contributing to the final diagnosis of FVPTC was calculated for each diagnostic category. Triage efficiency and diagnostic accuracy were calculated. One hundred and fifty-two cases with histologic confirmation of FVPTC were identified (representing 128 patients-101 female, 27 male). All patients had undergone either lobectomy with completion thyroidectomy or total thyroidectomy. The cytologic diagnosis of "positive for malignancy" accounted for only 27 % of the final histologic diagnosis of FVPTC, while suspicious for carcinoma, follicular neoplasm, follicular lesion of undetermined significance, and benign accounted for 11, 23, 23, and 16 % of the final diagnosis of FVPTC, respectively. Only 18 % of the 55 cases tested were positive for BRAF mutation. The subtle nuclear features of FVPTC pose challenges for an accurate diagnosis. Therefore, a better approach is to triage these cases for surgical intervention and/or further evaluation of the particular nodule. Our triage efficacy for FVPTC was 84 %; however, the diagnostic accuracy of PTC was 38 %. A negative diagnosis on FNA has diagnostic and management implications for up to 16 % of cases because they may have no further immediate diagnostic studies or treatment. BRAF mutation analysis provides minimal effect on diagnostic accuracy.

Cell blocks in cytopathology: a review of preparative methods, utility in diagnosis and role in ancillary studies

The cell block (CB) is a routine procedure in cytopathology that has gained importance because of its pivotal role in diagnosis and ancillary studies. There is no precise review in the published literature that deals with the various methods of preparation of CB, its utility in diagnosis, immunocytochemistry (ICC) or molecular testing, and its drawbacks. An extensive literature search on CB in cytology using internet search engines was performed for this review employing the following keywords: cell block, cytoblock, cytology, cytopathology, methods, preparation, fixatives, diagnostic yield, ancillary and molecular studies. Ever since its introduction more than a century ago, the CB technique has undergone numerous modifications to improve the quality of the procedure; however, the overall principle remains the same in each method. CBs can be prepared from virtually all varieties of cytological samples. In today's era of personalized medicine, cytological specimens, including CBs, augment the utility of cytological samples in analysing the molecular alterations as effectively as surgical biopsies or resection specimens. With the availability of molecular targeted therapy for many cancers, a large number of recent studies have used cytological material or CBs for molecular characterization. The various techniques of CB preparation with different fixatives, their advantages and limitations, and issues of diagnostic yield are discussed in this review.

Role of ancillary testing in thyroid fine needle aspiration: Review and update

Thyroid nodules are common, and ultrasound-guided fine needle aspiration identifies 70-75% as benign, and 4% as malignant. The remainder falls into categories of "indeterminate" with a widely ranging malignancy rate from 10-75%. The diagnosis and clinical management of indeterminate lesions is evolving, and we will review ancillary testing as an aid to diagnosis.

Immunohistochemical expression of HBME-1 and galectin-3 in the differential diagnosis of follicular-derived thyroid nodules

BACKGROUND

Thyroid nodules are common among adults with only a small percentage being malignant and histologically mimic benign nodules. Accurate diagnosis of these thyroid nodules is critical for the proper clinical management. The determination of malignancy in follicular patterned thyroid lesions is based on postoperative histological findings. Therefore, affected patients are referred for surgery, although only 10% will have a final diagnosis of malignancy. The aim of this study was to investigate the ability of two immunohistochemical (IHC) markers; galectin-3 and Hector Battifora mesothelial-1 (HBME-1) individually or in combination, to distinguish between benign (non-neoplastic and neoplastic) and malignant (follicular and papillary carcinomas) thyroid lesions removed by surgical resection.

METHODS

We investigated the immunoexpression of galectin-3 and HBME-1 in 50 cases of benign and malignant thyroid nodules. The benign group included 13 cases of thyroid nodular goiter (NG) and 9 cases of follicular adenoma (FA). The malignant group included 5 cases of follicular thyroid carcinomas (FC), 18 cases of classic papillary thyroid carcinoma and 5 cases of follicular variant papillary carcinoma (FVPC).

RESULTS

The staining results showed that malignant tumors expressed galectin-3 and HBME-1 significantly more than benign nodules. The sensitivity of these markers for the distinction between benign and malignant lesions ranged from 89.3% to 92.9%. Co-expression of galectin-3 and HBME-1 was seen in 82.1% of carcinomas, but in none of the benign nodules. Immunoexpression was usually diffuse in malignant tumors, and focal in the benign lesions.

CONCLUSION

Our findings indicate that these immunohistochemical markers are significantly more expressed in malignant tumors compared to benign lesions and may be of additional diagnostic value when combined with routine histology. Galectin-3 has higher sensitivity and specificity of immunoexpression in thyroid malignancy than HBME-1, and the combined use of galectin-3 and HBME-1 can increase the specificity of immunoexpression in malignant tumors.