Analyzing the impact of molecular testing on the cytological diagnosis of thyroid nodules: Insights from our institution's experience.

Thyroid malignancy is one of the most common types of cancer in developed nations. Currently, fine-needle aspiration cytology (FNAC) is the most practical screening test for thyroid nodules. However, cytologically indeterminate samples comprise approximately 15%-30% of cases. These include cases classified as atypia of undetermined significance (AUS), follicular neoplasm (FN), and suspicious for malignancy (SFM). Indeterminate cases can be sent for molecular testing for more definitive classification to help guide management and prevent overtreatment of benign thyroid nodules. We conducted a retrospective review on molecular testing of indeterminate thyroid FNAC and reviewed subsequent histologic diagnoses in resection specimens to assess how molecular testing supported a diagnosis and its effect on clinical management of patients at our institution. A retrospective chart review was performed on all thyroid FNAC specimens, corresponding molecular testing, and subsequent surgical resection specimens over a 6-year period. A total of 10,253 thyroid FNAC were performed in our hospital system during our study period, of which 10% (n = 1102/10,253) had indeterminate FNAC results. Molecular testing was performed in 16% (n = 178/1102) of indeterminate cytology cases. Genetic alterations were identified in 39% (n = 69/178) of the cases sent for molecular testing. The majority of cytologically indeterminate cases sent for molecular testing were follicular-patterned lesions and their corresponding resection specimens revealed mostly low grade follicular derived neoplasms (i.e., follicular adenoma, non-invasive follicular thyroid neoplasm with papillary-like nuclear features, and follicular variant of papillary thyroid carcinoma). Of the cases with identified genetic alterations, 75% (n = 52/69) were treated surgically. In cases with no genetic alterations identified, only 18% (n = 20/109) were treated surgically. Molecular testing on cytologically indeterminate thyroid nodules can help provide a more accurate risk of malignancy assessment in patients with lesions that are difficult to diagnosis based solely on FNAC morphology. The types of genetic alterations identified in the resected thyroid lesions were consistent with what has been previously described in the literature. Additionally, we found that in the patients with indeterminate thyroid FNAC with adjunct molecular testing, more than half did not undergo surgical resection. This finding emphasizes the value of adding molecular testing in patients, particularly when attempting to reduce unnecessary surgical intervention.

Mutation profiling of thyroid liquid-based fine needle aspirations improves diagnostic accuracy

BackgroundThis study was performed to analyze cytologic diagnosis of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and its impact on the risk of malignancy (ROM) in the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). MethodsFive thousand five hundred and forty-nine cases of thyroid fine-needle aspiration cytology (FNAC) diagnosed between 2012 and 2014 were included in this study. Diagnostic categories based on TBSRTC were compared with final surgical diagnoses, and the ROM in each category was calculated both when NIFTP was included in malignant lesions and when excluded from malignant lesions. ResultsOf the 5,549 thyroid FNAC cases, 1,891 cases underwent surgical resection. In final diagnosis, 1,700 cases were revealed as papillary thyroid carcinoma (PTC), and 25 cases were reclassified as NIFTP. The cytologic diagnoses of NIFTP were non-diagnostic in one, benign in five, atypia of undetermined significance (AUS) in 14, follicular neoplasm in two, and suspicious for malignancy in three cases. Collectively, NIFTP/encapsulated follicular variant of PTC (EFVPTC) were more frequently classified as benign, AUS, or follicular neoplasm and less frequently categorized as malignant compared to conventional PTCs. Exclusion of NIFTP from malignant diagnoses resulted in a slight decrease in malignancy rates in non-diagnostic, benign, AUS, follicular neoplasm, and suspicious for malignancy categories without any statistical significance. ConclusionsThe decrease in the ROM was not significant when NIFTP was excluded from malignant lesions. In thyroid FNACs, NIFTP/EFVPTCs were mostly classified into indeterminate categories. Therefore, it might be feasible to separate NIFTP/EFVPTC from conventional PTC on FNAC to guide clinicians to conservative management for patients with NIFTP/EFVPTC.

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has provided a set of uniform diagnostic terminology including benign (B), atypia of undetermined significance (AUS), follicular neoplasm (FN), suspicious for malignancy (SM), malignancy (M), and nondiagnostic (ND) for the interpretation of thyroid fine-needle aspiration (FNA). We applied this terminology on our 1,382 thyroid aspirates in a community practice setting, which included 539 cases of B (39%), 376 cases of AUS (27.2%), 116 cases of FN (8.4%), 37 cases of malignant (2.7%), 36 cases of SM (2.6%), and 278 cases of ND (20.1%). Two hundred twenty-one cases (16%) of thyroid FNA had corresponding follow-up thyroidectomies. Each diagnostic category represented a unique association with risk of malignancy and risk of neoplasm. Based on histologic follow-up, the risk of neoplasm (including benign and malignant neoplasm) was B 14%, AUS 44%, FN 67%, SM 77%, and M 100% and the risk of malignancy was B 3%, AUS 6%, FN 22%, SM 56%, and M 100%. The classification and follow-up recommendation of TBSRTC are appropriate for each category. Both B and AUS are low-risk lesions with low probability of malignancy. FN predicts a higher rate for neoplasm but an intermediate rate for malignancy while SM carries a high risk for malignancy.

Introduction: Fine Needle Aspiration Cytology (FNAC) is the first line diagnostic procedure for evaluating thyroid lesions. The present study was carried out to assess the diagnostic utility of thyroid FNAC using The Bethesda System for Reporting Thyroid Cytopathology. Materials and Methods: It was a one year prospective study conducted in the Department of Pathology, Government Medical College, Jammu and included all patients presenting with thyroid swelling referred to this department. The thyroid fine needle aspirates from these patients were classified into six categories according to The Bethesda System for Reporting Thyroid Cytopathology. The Risk of Malignancy was calculated for each Bethesda category by follow-up histopathology. Sensitivity, Specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were also calculated using histopathology diagnosis as gold standard. Results: Thyroid fine needle aspirates from a total of 300 patients were classified according to Bethesda system as Nondiagnostic (ND)- 17cases(5.67%), Benign- 264cases(88%), Atypia of Undetermined Significance (AUS)- 1case(0.33%), Follicular Neoplasm(FN)-6cases(2%), Suspicious for malignancy(SFM)- 0case( 0%) and Malignant- 12cases(4%). The Risk of Malignancy was Nondiagnostic- 50%, Benign-0%, AUS-0%, FN-50%, Suspicious for malignancy-not possible, Malignant-100%. Sensitivity, Specificity, PPV and NPV were 100%, 100%, 100%, 100% (FN excluded); 80%, 100%, 100%, 96% (FN included as benign); and 100%, 95.83%, 83.33%, 100% (FN included as malignant). Conclusion: The present study concludes Bethesda system to be an effective reporting system for thyroid cytology, FNAC to be a sensitive and specific test for evaluation of thyroid lesions and FNAC using Bethesda guidelines is useful in risk assessment of thyroid nodules thereby guiding appropriate management. Keywords:Thyroid fine needle aspiration cytology, Bethesda system, Risk of malignancy, Sensitivity, Specificity.

Risk of malignancy associated with indeterminate categories in the Milan System for reporting pediatric salivary gland cytopathology: a multi-institutional study.

Use of molecular testing results to analyze the overuse of atypia of undetermined significance in thyroid cytology

Hürthle cell lesions often pose diagnostic challenges, despite their common occurrence on thyroid fine-needle aspiration cytology (FNAC). The associated molecular alterations are also not well understood. Therefore, our study aimed to delineate the molecular profile of Hürthle cell lesions classified as Bethesda Categories III or IV (atypia of undetermined significance (AUS) or suspicious for follicular neoplasm (SFN)) on FNAC and to correlate this molecular profile with surgical resection findings. This study consisted of 188 Hürthle cell lesions with indeterminate cytology and ThyroSeq® v2/v3 molecular testing results. Surgical follow-up was available for 33 cases. The majority of indeterminate Hürthle cell lesions had negative ThyroSeq® results (61%) and were benign on available surgical follow-up. The most prevalent mutations involved the RAS gene (21%), which were associated with benign lesions, non-invasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP), and malignancy. The remaining mutations involved less than 18% of the cases, including PAX8/PPARG (3.7%), TSHR (3.7%), EIF1AX (2.7%), MET (2.1%), PTEN (1.6%), clonal copy number alteration (1.6%), TERT (1.1%), and 0.5% each of GNAS, PIK3CA, and TP53 mutations. On follow-up, 45% were benign, 24% were NIFTP, and 30% were malignant. The malignant cases had different molecular alterations. No single molecular alteration defines cytologically indeterminate Hürthle cell lesions; the majority of cases have low-risk or no molecular alterations and are benign on follow-up. These findings suggest that molecular testing may be useful, but is not definitive, in determining which cases may be managed conservatively; additional studies are needed to fully determine the negative predictive value in ruling out malignancy.

The Bethesda System for Reporting Thyroid Cytology (BSFRTC) is widely adopted in the management of thyroid nodules. The system was updated in 2017, and its impact is the subject of this paper. All thyroid fine needle aspirations from 2016-2020 using the BSFRTC, with follow-up surgical pathology, were reviewed. The risk of neoplasia (RON), risk of malignancy (ROM), RON/ROM ratio, and surgical follow-up rate were determined for each diagnostic category with cytohistological correlation. ROM was calculated in two separate manners, with non-invasive follicular tumours with papillary-like nuclear features (NIFTP) counted as malignant or non-malignant. Sensitivity, specificity, negative and positive predictive values were determined for indeterminate categories: atypia of undetermined significance (AUS), suspicious for follicular neoplasm (SFN), and suspicious for malignancy (SFM). RON, ROM, and the surgical follow-up rate increased steadily from the benign through intermediate to malignant categories. The omission of NIFTP from malignant lesions reduced the calculated ROM in indeterminate categories and improved the stratification between AUS and SFN. ROM in AUS was distinct from SFN. AUS has a well-balanced sensitivity and specificity favouring a screening rather than a diagnostic category. The calculated RON/ROM was significantly higher in AUS (1.56), compared to SFN (1.03) and SM (1.05), in agreement with current BSRTC management recommendations. AUS is an important screening category and should remain with the addition of subcategorisation. RON and surgical follow-up rates are essential quality indicators. The RON/ROM ratio could be utilised to determine appropriate management for each diagnostic category on an institutional basis.

Background: Fine-needle aspiration cytology (FNAC) is a safe, reliable, and non-invasive diagnostic procedure for thyroid lesions, effectively reducing unnecessary surgical biopsies. This outpatient procedure enables rapid and accurate evaluation of thyroid nodules. Objective: This study aimed to analyze the cytological spectrum of thyroid lesions and evaluate the diagnostic efficacy of FNAC using the Bethesda classification system. Materials and Methods: A cross-sectional study was conducted over one month at the Pathology Department of King Edward Medical University/Mayo Hospital, Lahore, involving 82 patients with thyroid nodules. FNAC was performed using 22–24-gauge needles, with samples processed per standard fixation and staining protocols. Statistical Analysis: Data was analyzed using SPSS version 23. Qualitative variables (e.g., lesion type) were reported as frequencies and percentages, while quantitative variables (e.g., age) were expressed as mean ± SD. Results: Of 82 aspirates, distribution by Bethesda categories was: non-diagnostic (ND) 16 (19.5%), benign (BN) 36 (43.9%), follicular neoplasm (FN) 13 (15.8%), atypia of undetermined significance (FLUS) 10 (12.2%), suspicious for malignancy (SM) 5 (6.1%), and malignant 2 (2.4%). Thyroid lesions predominated in women (69%) compared to men (31%), with the highest incidence in patients aged 30–40 years. Conclusion: The Bethesda system standardized FNAC reporting, identifying higher malignancy risks in FLUS, FN, and SM categories. FNAC proved to be a safe, timely, and first-line diagnostic tool for thyroid nodules.

Background: The Bethesda System has been used to classify thyroid cytology in 6 categories besides presenting malignancy rates and respective approaches. Reference centers have validated its use by comparing its proposed malignancy rates with those in in their populations. However, to the best of our knowledge, there has been no corresponding study in Brazil. Objectives: To evaluate the performance of the Bethesda classification in a Brazilian thyroid reference center and correlate the results with cytohistological reports in patients referred to surgery. Methods: Data records from 980 fine-needle aspiration (FNA) results were retrospectively analyzed, and, in patients who underwent surgery, the results were correlated with the cytohistological findings. Results: 980 FNAs and 585 patients were evaluated. The incidence of each cytological category was: 11% nondiagnostic (ND), 59.6% benign, 7.1% (atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS), 8.5% follicular neoplasm or suspicious for follicular neoplasm (FN/SFN), 5.1% suspicious for malignancy (SM), and 8.3% malignant. The surgery rate was 41.8% (245/585). The malignancy rate in each category was: 6% benign, 12% AUS/FLUS, 20.8% FN/SFN, 72.5% SM, and 97.3% malignant. For ND nodules, the malignancy rate was 25.7% (66.6% multifocal and papillary microcarcinomas), a higher rate than in the literature. In this category, surgery was performed in multinodular goiters presenting with another nodule > 3.0 cm and/or with an FN/SFN, SM, or malignant cytological result. Conclusion: The Bethesda System can be applied to the Brazilian population, since the frequency and malignancy rates of each category were similar to those described by its classification. It is noteworthy that a higher risk of malignancy was observed in the ND cytological category.

Evidence guiding the management of cytologically indeterminate thyroid nodules with nondiagnostic (ND) or benign cytology on repeat fine-needle aspiration (FNA) is limited. This study evaluates the utility of molecular testing and estimates the risk of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and cancer among such nodules. This was a retrospective single-institution review of thyroid nodules from adults that were classified as atypia of undetermined significance (AUS) or follicular neoplasm (FN) on initial FNA and underwent repeat FNA for cytology and Afirma testing (June 2013-July 2021). The association between repeat FNA cytology and RNA yield for Afirma was determined. Histologic outcomes were integrated with Afirma results to define end points for each nodule. A total of 691 AUS and FN nodules underwent repeat FNA and Afirma testing. Diagnostic Afirma results were obtained in 98% of cases overall and in 91% of nodules with ND cytology on repeat FNA. Using combined molecular and histologic end points, the NIFTP and/or cancer prevalence for nodules with ND cytology on repeat FNA was 9% (95% confidence interval [CI], 0.042-0.182), falling between those nodules classified as benign (5%; 95% CI, 0.029-0.094) and those classified as AUS or FN (18%; 95% CI, 0.140-0.218) on repeat FNA, although not reaching statistical significance from either subgroup (p=.38 and .10, respectively). AUS and FN nodules that are ND on repeat FNA have low but nonnegligible risk of NIFTP and/or cancer and may benefit from molecular testing, given the low test failure rate in this subgroup. Conversely, AUS and FN nodules reclassified as benign on repeat FNA have a very low risk of NIFTP and/or cancer and are unlikely to benefit from molecular testing.

Background : Thyroid nodules are very common; however, only 5–15% of nodules are malignant. Although most of the malignant thyroid cancers can be identified pre-operatively by cytological analysis, approximately 20–30% of these nodules are classified indeterminate. Subsequently, repeated Fine Needle Aspiration (FNA) or thyroid surgery may be required for a more definitive diagnosis. In the United States, the incidence of thyroid cancer has tripled from 1975 with an incidence rate of 14.3 per 100,000 individuals, primarily due to an increased diagnosis of papillary thyroid cancer which increased by 9.1 per 100,000 (RR 3.7, 95% CI (3.4–4.0)); however, mortality has remained stable. Many patients with cytologically indeterminate nodules undergo unnecessary diagnostic surgeries, placing them at risk of potential surgical complications and need for lifelong levothyroxine replacement. The advent of molecular gene testing has drawn significant attention toward improved stratification of these indeterminate lesions into benign or malignant. Detection of any pertinant molecular mutations in the indeterminate categories- atypia of undetermined significance (AUS)/ follicular lesion of undetermined significance (FLUS), follicular neoplasm (FN)/suspicious for a follicular neoplasm (SFN), and suspicious for malignant cells (SMC) has been shown to confer the risk of histologic malignancy of 88, 87 and 95% respectively, while a negative test for the mutation was reassuring with a very high negative predictive value over 95%. Purpose : The purpose of this article is to review the current recommendations to implement molecular genetic testing for thyroid nodules. We review the most common gene mutations harbored in the various thyroid cancers, including BRAF, RAS, and RET/PTC. We will also review the more recently discovered gene mutations for thyroid cancer, including TERT mutations. Finally, we will discuss the practice guidelines to implement molecular gene testing for the indeterminate cytology of thyroid nodules as well as the new category of non-invasive follicular thyroid neoplasm with papillary-like nuclear features as an intermediate pathology which will not require aggressive therapy after diagnostic lobectomy. (Published: 13 December 2016) Citation: Advances in Cellular and Molecular Otolaryngology 2016, 4: 33948 - http://dx.doi.org/10.3402/acmo.v4.33948

Fine needle aspiration cytology (FNAC) is a cost-effective diagnostic technique for evaluation of salivary gland lesions. But, then, cytological evaluation of salivary gland lesions also has lot of challenges. To overcome the difficulties, “The Milan system for reporting salivary gland cytopathology” (MSRSGC) was introduced for diagnosis and management and establishing the risk of malignancy (ROM) in different categories. The present study was conducted to grade the salivary gland lesions according to Milan system of reporting and to correlate with their histopathological findings. The current study was conducted in the department of Pathology, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth, Pondicherry for a period of 5 years. Around 153 salivary gland lesions were aspirated. Salivary gland swellings were examined clinically, correlated with the details on the request forms and ultrasound findings, palpated and aspirated. The cytological features were evaluated and categorized according to Milan System for Reporting Salivary Gland Cytopathology”: Category 1: Nondiagnostic (ND); Category 2: Non-neoplastic (NN); Category 3: Atypia of undetermined significance (AUS); Category 4a: Neoplasm: benign (NB), Category 4b: Neoplasm: salivary gland neoplasm of uncertain malignant potential (SUMP); Category 5: suspicious of malignancy (SM); and Category 6: Malignant (M). They were further correlated with histopathological findings. All data were entered in MS excel sheet.Total 153 cases were evaluated cytologically, and histological followup was available in 134 cases. The distribution of cases into different categories were as follows Non-Diagnsotic (2.6%), Non-Neoplastic (20.9%), Atypia of Undetermined Significance (1.9%), Neoplastic-Benign (41.1%),Salivary gland neoplasm of Uncertain Malignant Potential (0%), Suspicious of Maligancy (0%) and Malignancy (33.3 %). Risk of malignancy were observed in categories 2 and 6 and were 3.84 % and 78.2 %. Sensitivity of FNAC in diagnosing salivary gland lesions was 84.2 %, specificity was 98.21%,positive predictive value was 94.64%, and negative predictive value was 91.70% with an accuracy of 93.60%.MSRSGC is a novel reporting system in cytological diagnosis of salivary gland lesions. Implementation of this reporting system in cytological diagnosis has enabled establishment of adequate diagnosis, assessment of risk stratification and facilitating clinicians to take further step in management plan.

Malignancy risk and reproducibility associated with atypia of undetermined significance on thyroid cytology