Reliably making the primary diagnosis of mesothelioma utilizing serous fluid cytology specimens: an institutional experience.

INTRODUCTION: The diagnosis of mesothelioma has historically been challenging, especially on serous fluid cytology (SFC). Distinguishing between reactive and neoplastic mesothelial cells can be difficult on cytomorphology alone. However, additional ancillary tests, such as BRCA1 associated protein-1 immunohistochemistry and fluorescence in situ hybridization for cyclin-dependent kinase inhibitor 2A deletion, can provide a sensitive and highly specific method of proving malignancy. MATERIALS AND METHODS: SFC specimens diagnosed as mesothelioma, suspicious for mesothelioma (SM), and atypical mesothelial cells (AMCs) since 2012 were identified by querying the laboratory information system. Clinical data and pathologic parameters were gathered. RESULTS: One hundred ten cases of mesothelioma, SM, and AMC were identified. Of these, 61 cases had a definitive diagnosis of mesothelioma on SFC. Average age at SFC diagnosis was 67 years (26-87 years), with most patients being male (67%). Out of the 61 cases, 11 cases (18%) had an initial diagnosis of mesothelioma made on SFC specimens, with 5 of these 11 cases being in patients that never received a histologic diagnosis of mesothelioma. Ancillary studies were utilized in all 11 cases. An initial diagnosis of metastatic mesothelioma was made on SFC in 9 cases (15%). For 6 of these 9 cases, the SFC diagnosis was the sole diagnosis of metastatic mesothelioma without a companion histologic diagnosis. In addition, 15 cases were diagnosed as SM, with 11 of these cases following a definitive mesothelioma diagnosis. Thirty-four cases were diagnosed as AMC, with 27 cases following a definitive mesothelioma diagnosis. CONCLUSIONS: The diagnosis of mesothelioma can be reliably made on SFC with the appropriate cytomorphology criteria and/or confirmatory ancillary testing.

Molecular-derived risk of malignancy and the related positive call rate of indeterminate thyroid cytology diagnoses as quality metrics for individual cytopathologists.

BACKGROUND: Indeterminate thyroid cytopathology diagnoses represent differing degrees of risk that are corroborated by follow-up studies. However, traditional cytologic-histologic correlation may overestimate the risk of malignancy (ROM) because only a subset of cases undergo resection. Alternatively, some molecular tests provide probability of malignancy data to calculate the molecular-derived risk of malignancy (MDROM) and the positive call rate (PCR). The authors investigated MDROMs and PCRs of indeterminate diagnoses for individual cytopathologists as quality metrics. METHODS: This study was approved by the Department of Pathology Quality Improvement Program. Thyroid cytopathology diagnoses and ThyroSeq v3 results were retrieved for each cytopathologist for a 2-year period with at least 3 years of follow-up for the atypia of undetermined significance (AUS), follicular neoplasia (FN), and follicular neoplasia, oncocytic-type (ONC) cytopathologic diagnoses. MDROMs and PCRs were compared with reference ROMs and cytologic-histologic correlation outcomes. RESULTS: The overall MDROMs (and ranges for cytopathologists) for the AUS, FN, and ONC categories were 13.4% (range, 5.8%-20.8%), 28.1% (range, 22.1%-36.7%), and 27.0% (range, 19.5%-41.5%), respectively, and most individual cytopathologists' MDROMs were within reference ROM ranges. However, PCRs more effectively parsed the differences in cytopathologists' ROM performance. Although the overall PCRs were not significantly different across cytopathologists (p = .06), the AUS PCRs were quite different (p = .002). By cytologic-histologic correlation, six of 55 resected cases (10.9%) were falsely negative, and there were no false-positive cases. CONCLUSIONS: MDROMs and PCRs evaluate concordance with reference ROMs and with one another and provide individual feedback, which potentially facilitates quality improvement.

Molecular Testing Predicts Incomplete Response to Initial Therapy in Differentiated Thyroid Carcinoma Without Lateral Neck or Distant Metastasis at Presentation: Retrospective Cohort Study.

Background: Molecular testing (MT) is emerging as a potential prognostic factor that can be available before treatment of differentiated thyroid carcinoma begins. Among patients eligible for either lobectomy or total thyroidectomy as their initial therapy, our study aims were to assess (1) if conventionally available preoperative factors are associated with incomplete response to initial therapy, and (2) if MT results can be a surrogate for the ATA Risk Stratification System (RSS) to estimate risk of recurrence. Methods: The data of consecutive thyroid cancer patients without preoperative lateral neck disease or distant metastasis who underwent index thyroidectomy between November 1, 2017 and October 31, 2021 were reviewed. Logistic regression models including preoperative variables such as MT and/or the postoperatively available RSS were constructed to predict disease recurrence, either structural or biochemical. Model discrimination using the c-statistic and goodness-of-fit test were compared. Results: Among 945 patients studied, 50 (5.2%) recurred with 18-month median follow-up. Recurrences were detected in 17 (2.9%), 20 (6.7%), and 13 (22.8%) patients with RSS-low, -intermediate, and -high cancers, respectively (p < 0.001). In multivariable analysis, only tumor size was associated with recurrence (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.1-1.5). In a different model analyzing 440 (46.6%) patients with available MT results, recurrence was associated with both larger tumor size (OR 1.4 [95% CI 1.1-1.8]) and MT results (p < 0.001). Including MT improved the c-statistic by 27%, which was statistically no different than the model incorporating only the RSS (p = 0.15). Conclusions: Disease recurrence was observed across all ATA RSS categories in short-term follow-up, and tumor size was the only conventional preoperative factor associated with recurrence. When MT results were incorporated, they not only improved predictive ability beyond tumor size alone, but also yielded similar ability as the gold standard ATA RSS. Thus, MT results might aid the development of novel preoperative risk stratification algorithms.

A thyroid EIF1AX story: how clinical, cytologic, and molecular surveillance led to appropriate management.

INTRODUCTION: Indeterminate thyroid cytology diagnoses are associated with intermediate risks of malignancy. Application of molecular testing (MT) to indeterminate specimens provides additional diagnostic and prognostic information. While a positive or suspicious MT result may prompt surgery, a negative MT result is associated with a low probability of cancer or noninvasive follicular thyroid neoplasm with papillary-like nuclear features and approximates that of a benign cytology diagnosis. Furthermore, ThyroSeq v3 MT has a "currently negative" result for findings with the probability of cancer or noninvasive follicular thyroid neoplasm with papillary-like nuclear feature that is slightly greater than that for the negative ThyroSeq v3 MT result but less than 10%, suggesting active surveillance. In this report, we discuss a case of a patient for whom clinical, cytologic, and molecular surveillance led to timely surgery and management. CLINICAL DETAILS: A 53-year-old man with a thyroid isthmus nodule had a fine-needle aspiration cytology diagnosis of atypia of undetermined significance and a subsequent ThyroSeq v3 MT, which revealed an EIF1AX mutation and a "currently negative" MT result. Surveillance with additional fine-needle aspiration samples demonstrated concerning genomic alterations (fluctuating EIF1AX allelic frequency and a non-V600E BRAF mutation), culminating in the conversion to a positive MT result 3 years later. Resection revealed an encapsulated noninvasive, oncocytic solid subtype of papillary thyroid carcinoma with increased mitotic activity. CONCLUSION: The case is notable for clinical, cytologic, and molecular surveillance demonstrating sequential pathologic alterations in an indeterminate thyroid nodule with EIF1AX mutation, leading to timely resection of the neoplasm before invasion manifested.

Changes in thyroid nodule cytology rates after institutional implementation of the Thyroid Imaging Reporting and Data System.

BACKGROUND: The American College of Radiology Thyroid Imaging Reporting and Data System for ultrasound classification of malignancy risk was developed to better triage thyroid nodules for fine-needle aspiration biopsy. To examine further, we compared thyroid cytologic classification rates in nodules before and after institutional Thyroid Imaging Reporting and Data System implementation. METHODS: Cytology diagnoses by Bethesda criteria (categories I-VI) from January 2014 to October 2021 were retrieved; observed changes in yearly category frequency were analyzed by linear regression; and pooled cohorts of pre- (2014-2018) and post-Thyroid Imaging Reporting and Data System (2019-2021) cytology call rates were compared. RESULTS: Overall, 7,413 cytologic specimens were included (range/year 715-1,444). From 2014 to 2021, the proportion of benign (Bethesda category II) diagnosis per year declined stepwise from 49.7% to 19.4%, and atypia of undetermined significance/follicular lesion of undetermined significance (Bethesda category III) increased sequentially from 21.3% to 51.5%. Between 2014 and 2021, Bethesda category III diagnosis increased on average by 4.8% per year (95% confidence internal, 3.29-5.54; P < .001) and Bethesda category II results decreased on average by 4.4% per year (95% confidence interval, 6.29-3.42; P < .001). When comparing pre- and post-Thyroid Imaging Reporting and Data System, the proportion of Bethesda category II cytology results decreased (43.1% vs 21%; P = .001) while Bethesda category III (28.3% vs 47.7%; P = .002) and Bethesda category V (1.1% vs 1.7%; P = .015) results increased. CONCLUSION: After implementation of American College of Radiology Thyroid Imaging Reporting and Data System ultrasound criteria, we observed a 2.5-fold decline in the rate of benign cytology and an increase in the proportion of atypia of undetermined significance/follicular lesion of undetermined significance results.

Association of comprehensive thyroid cancer molecular profiling with tumor phenotype and cancer-specific outcomes.

BACKGROUND: Molecular testing improves the diagnostic accuracy of thyroid cancer. Whether specific molecular testing results are associated with tumor phenotype or provide prognostic information needs further delineation. METHODS: Consecutive thyroid cancer patients after index thyroidectomy with ThyroSeq version 3 (Rye Brook, NY) molecular testing obtained on preoperative fine-needle aspiration or thyroidectomy specimens from patients with thyroid cancer were categorized into 3 molecular risk groups based on detected mutations, fusions, copy number alterations, and/or gene expression alterations and correlated with histopathology and recurrence, defined as biochemical or structural. RESULTS: Of 578 patients, 49.9%, 37.5%, and 12.6% had molecular risk group-low, molecular risk group-intermediate, and molecular risk group-high cancers, respectively. With a median 19-month follow-up, 9.1% patients recurred. Compared with molecular risk group-low, molecular risk group-intermediate cancers were diagnosed in younger patients and more often had microscopic extrathyroidal extension, involved margins, and nodal disease. Compared with molecular risk group-intermediate, molecular risk group-high cancers were diagnosed in older patients and more often had gross extrathyroidal extension and vascular invasion. In multivariable analysis, recurrence was more likely in molecular risk group-high cancers than in molecular risk group-intermediate (hazard ratio = 4.0; 95% confidence interval, 1.9-8.6; P < .001) and more likely in molecular risk group-intermediate than in molecular risk group-low (hazard ratio = 5.0; 95% confidence interval, 2.0-12.5; P < .001). CONCLUSION: Using modern comprehensive genotyping, the genetic profile of thyroid cancers can be categorized into 3 novel molecular risk groups that were associated with histopathologic phenotype and recurrence in short-term follow-up.

Prospective, Multi-Institutional, Real-Time Next-Generation Sequencing of Pancreatic Cyst Fluid Reveals Diverse Genomic Alterations That Improve the Clinical Management of Pancreatic Cysts.

BACKGROUND & AIMS: Next-generation sequencing (NGS) of pancreatic cyst fluid is a useful adjunct in the assessment of patients with pancreatic cyst. However, previous studies have been retrospective or single institutional experiences. The aim of this study was to prospectively evaluate NGS on a multi-institutional cohort of patients with pancreatic cyst in real time. METHODS: The performance of a 22-gene NGS panel (PancreaSeq) was first retrospectively confirmed and then within a 2-year timeframe, PancreaSeq testing was prospectively used to evaluate endoscopic ultrasound-guided fine-needle aspiration pancreatic cyst fluid from 31 institutions. PancreaSeq results were correlated with endoscopic ultrasound findings, ancillary studies, current pancreatic cyst guidelines, follow-up, and expanded testing (Oncomine) of postoperative specimens. RESULTS: Among 1933 PCs prospectively tested, 1887 (98%) specimens from 1832 patients were satisfactory for PancreaSeq testing. Follow-up was available for 1216 (66%) patients (median, 23 months). Based on 251 (21%) patients with surgical pathology, mitogen-activated protein kinase/GNAS mutations had 90% sensitivity and 100% specificity for a mucinous cyst (positive predictive value [PPV], 100%; negative predictive value [NPV], 77%). On exclusion of low-level variants, the combination of mitogen-activated protein kinase/GNAS and TP53/SMAD4/CTNNB1/mammalian target of rapamycin alterations had 88% sensitivity and 98% specificity for advanced neoplasia (PPV, 97%; NPV, 93%). Inclusion of cytopathologic evaluation to PancreaSeq testing improved the sensitivity to 93% and maintained a high specificity of 95% (PPV, 92%; NPV, 95%). In comparison, other modalities and current pancreatic cyst guidelines, such as the American Gastroenterology Association and International Association of Pancreatology/Fukuoka guidelines, show inferior diagnostic performance. The sensitivities and specificities of VHL and MEN1/loss of heterozygosity alterations were 71% and 100% for serous cystadenomas (PPV, 100%; NPV, 98%), and 68% and 98% for pancreatic neuroendocrine tumors (PPV, 85%; NPV, 95%), respectively. On follow-up, serous cystadenomas with TP53/TERT mutations exhibited interval growth, whereas pancreatic neuroendocrine tumors with loss of heterozygosity of ≥3 genes tended to have distant metastasis. None of the 965 patients who did not undergo surgery developed malignancy. Postoperative Oncomine testing identified mucinous cysts with BRAF fusions and ERBB2 amplification, and advanced neoplasia with CDKN2A alterations. CONCLUSIONS: PancreaSeq was not only sensitive and specific for various pancreatic cyst types and advanced neoplasia arising from mucinous cysts, but also reveals the diversity of genomic alterations seen in pancreatic cysts and their clinical significance.

Follicular Neoplasm of Thyroid Revisited: Current Differential Diagnosis and the Impact of Molecular Testing.

The diagnosis of "follicular neoplasm" (FN) in thyroid cytopathology has a long history that originated not long after the practice of fine-needle aspiration (FNA) of thyroid nodules. From the outset, this interpretive category was intended to convey a set of differential diagnoses rather than a precise diagnosis, as key diagnostic features, such as capsular and vascular invasion, were not detectable on cytology preparations. Cytologic-histologic correlation studies over the past several decades have shown that FN interpretation can be applied to the spectrum of nonneoplastic tumors to carcinomas. Most tumors classified as FN include follicular adenoma, follicular carcinoma, noninvasive follicular thyroid tumor with papillary-like nuclear features, and follicular variant of papillary thyroid carcinoma. Less common entities that may be classified as FN on FNA include hyalinizing trabecular tumor (HTT), poorly differentiated thyroid carcinoma, medullary carcinoma, and nonthyroidal lesions such as parathyroid tissue, paraganglioma, and metastatic tumors. Advances in our ability to detect characteristic molecular alterations (eg, GLIS gene rearrangements for hyalinizing trabecular tumor) in FNA samples may assist in the identification of some of these entities. In this review, we summarize the pathophysiology, history, and evolution of the terminology and the current differential diagnosis according to the recently published 2022 World Health Organization classification, molecular testing, and management of nodules classified as FN.

Identifying metastatic renal cell carcinoma in thyroid fine-needle aspirates by molecular testing.

Renal cell carcinoma (RCC) is the most common type of cancer found to metastasize to the thyroid gland. These tumors may represent a diagnostic challenge in cytology. However, most RCC tumors carry VHL alterations, which are rare in primary thyroid tumors. The aim of this study was to evaluate the utility of molecular testing in detecting metastatic RCC in thyroid fine-needle aspiration (FNA) samples. From November 2017 until March 2022, thyroid FNA samples with ThyroSeq v3 results showing both VHL alterations and low/absent expression of thyroid cell markers were analyzed. Eighteen samples from 15 patients met the inclusion criteria. On molecular analysis, deleterious VHL mutations were found in nine (50%) nodules, VHL copy number alteration (CNA) in two (11%), and both mutations and CNA in seven (39%). None of the cases showed mutations commonly found in thyroid tumors. The mean age of these patients was 68 (range, 49-89) years with a male to female ratio of 2:1. Eight (53%) patients had multiple thyroid nodules on ultrasound. On cytology, 14 (78%) nodules were diagnosed as Bethesda III, 2 (11%) as Bethesda IV, and 2 (11%) as Bethesda V. At the time of cytology review, the history of RCC, sometimes remote, was available for ten patients. Of the 14 patients with medical history or surgical follow-up available, all had history of RCC or renal mass or revealed metastatic RCC on thyroidectomy. This study demonstrates that molecular testing can reliably identify metastatic RCC in thyroid nodules with indeterminate cytology, which could improve patient management.

Performance of a Multigene Genomic Classifier in Thyroid Nodules with Suspicious for Malignancy Cytology.

Background: Molecular testing is increasingly used to refine the probability of cancer and assess recurrence risk in thyroid nodules with Bethesda III/IV fine needle aspiration (FNA) cytology. However, limited data exist for Bethesda V (suspicious for malignancy [SFM]) samples. This study evaluated the performance of ThyroSeq v3 (TSv3) in thyroid nodules with SFM cytology. Methods: In this single-institution retrospective cohort study, consecutive thyroid FNA samples diagnosed as SFM with TSv3 testing and known surgical outcome were identified. Clinical, pathology, and molecular findings were reviewed. The TSv3 Cancer Risk Classifier was used to determine molecular risk groups (MRGs). For test-negative cases diagnosed as cancer/noninvasive follicular thyroid neoplasm with papillary-like nuclear features, TSv3 was performed on the resected tumors. Results: Among 128 SFM samples studied, 100 (78.1%) were TSv3 positive, and 28 (21.9%) were negative. The cancer prevalence on surgery was 82.8%. Among test-positive samples, 95% were malignant and 5% benign. Among test-negative samples, 17 (60.7%) were benign and 11 (39.3%) malignant. Overall, TSv3 had a sensitivity of 89.6% (confidence interval; CI 82.4-94.1) and a specificity of 77.3% (CI 56.6-89.9). For a cancer prevalence of 50-75% expected in SFM cytology by the Bethesda system, the negative predictive value was expected to range from 71.2% to 88.1% and the positive predictive value from 79.8% to 92.2%. Among test-positive nodules, 20% were MRG-Low (mostly RAS-like alterations), 66% MRG-Intermediate (mostly BRAF-like alterations), and 14% MRG-High. Among patients with cancer, 65 (61.3%) were American Thyroid Association low risk, 25 (23.6%) intermediate risk, and 6 (5.7%) high risk. During the mean follow-up of 51.2 months (range: <1 to 470 months), 12 (13.0%) patients had disease recurrence, which was more common in MRG-High (54.6%) compared with MRG-Intermediate (9.5%) and MRG-Low (0%) cancers (p < 0.001). Upon reexamining tumors with false-negative results, half of evaluable cases had alterations likely missed due to limiting FNA sampling, and the remainder represented low-risk tumors. Potentially targetable alterations were identified in 10 samples. Conclusions: In this large series of SFM thyroid nodules, TSv3 further improved cancer prediction and detected RAS-like, BRAF-like, high-risk, and potentially targetable alterations, all of which may inform more optimal patient management. MRGs were associated with recurrence-free survival, offering potential preoperative cancer risk stratification.

Clinicopathologic Characteristics and Postsurgical Follow-Up of Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features in the Postnomenclature Revision Era.

Background: Noninvasive encapsulated follicular variant papillary thyroid carcinoma (EFVPTC) was reclassified as "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) in 2016. Most existing studies that examined outcomes included patients managed as EFVPTC and only retrospectively reclassified as NIFTP. This is the first study to evaluate the clinicopathologic, molecular, and surveillance characteristics of patients diagnosed with NIFTP at the time of surgery and managed based on this diagnosis. Methods: We performed a retrospective cohort study of consecutive cases diagnosed as NIFTP from June 2016 to October 2021 identified from electronic medical records at a large tertiary care institution. Patients with coexisting low-risk thyroid cancers ≥1.0 cm in size or any size aggressive histology were excluded, and review of demographic, clinical, imaging, cytologic, and molecular genetic data was performed. Initial care was delivered according to existing clinical guidelines, with a consensus institutional plan for five-year follow-up after surgery. Results: Among 79 patients with 84 nodules diagnosed as NIFTP after surgery, 83.5% (66/79) were women and the mean age was 51 years (range, 21-84). Mean NIFTP size was 2.4 cm (range 0.15-8.0). On ultrasound, the majority of nodules were categorized as thyroid imaging, reporting and data system TI-RADS 3 (55.3%, 42/76), and TI-RADS 4 (36.8%, 28/76). On cytology, they were typically diagnosed as Bethesda III (69.1%, 47/68) or Bethesda IV (23.5%, 16/68). Molecular testing was performed on 62 nodules, and molecular alterations were found in 93.5% (58/62). The most common alterations identified in NIFTP were RAS mutation (75.4%, 43/57), THADA fusion (12.3%, 7/57), and BRAFK601E mutation (7.0%, 4/57). Fifty-two (65.8%) patients underwent lobectomy and 27 (34.2%) total thyroidectomy, and no patient received completion thyroidectomy. Twenty-one patients (26.5%) had coexisting papillary or follicular microcarcinoma. None of the patients received radioiodine ablation. On a mean follow-up of 28.5 months (range, 6-69 months), no structural or biochemical recurrences were observed. Conclusions: In this large cohort of patients with NIFTP diagnosed at the time of surgery and managed typically by lobectomy with no radioiodine ablation, no evidence of tumor recurrence was identified on a limited follow-up. This finding supports indolent clinical course of NIFTP.

Accuracy of definitive rapid onsite evaluation cytopathology diagnoses: Assessment of potentially critical diagnoses as a quality assurance measure.

INTRODUCTION: Intraprocedural rapid onsite evaluation (ROSE) of cytology specimens enhances cytopathology practice. More recently, ROSE diagnoses, like frozen section (FS) diagnoses, have guided immediate clinical decisions. In this study, we evaluated the diagnostic accuracy of definitive ROSE diagnoses in our quality assurance system over a 52-month period. MATERIALS AND METHODS: Cytopathology cases with ROSE from January 2017 to April 2021were retrieved from our laboratory information system. After excluding cases that were deferred or nondiagnostic/unsatisfactory, each definitive ROSE diagnosis (ie, negative for malignant cells or positive for malignant cells) was categorized as having agreement or disagreement with the final diagnosis. For comparison, concordance of FS diagnoses from the same time period were tabulated and compared to those of ROSE diagnoses by using χ2 testing with P < 0.05 considered statistically significant. RESULTS: Of the 1649 ROSE diagnoses, there were 15 disagreements (0.9%) with 1 final moderate interpretive disagreement (0.06%). By comparison, of the 17,469 FS diagnoses, there were 141 disagreements (0.8%) with 49 final moderate or major interpretive disagreements (0.3%). The remaining disagreements were minor. There were no statistically significant differences in the rates of final moderate and major interpretive disagreements. CONCLUSIONS: The final interpretive disagreement rates for definitive ROSE and FS diagnoses were similar in this study. Given the expanding role of ROSE and its use for immediate clinical decisions in some cases, monitoring the accuracy of definitive diagnoses may serve as an initial quality assurance measure.

Tumor Size Differences Between Preoperative Endoscopic Ultrasound and Postoperative Pathology for Neoadjuvant-Treated Pancreatic Ductal Adenocarcinoma Predict Patient Outcome.

BACKGROUND & AIMS: The assessment of therapeutic response after neoadjuvant treatment and pancreatectomy for pancreatic ductal adenocarcinoma (PDAC) has been an ongoing challenge. Several limitations have been encountered when employing current grading systems for residual tumor. Considering endoscopic ultrasound (EUS) represents a sensitive imaging technique for PDAC, differences in tumor size between preoperative EUS and postoperative pathology after neoadjuvant therapy were hypothesized to represent an improved marker of treatment response. METHODS: For 340 treatment-naïve and 365 neoadjuvant-treated PDACs, EUS and pathologic findings were analyzed and correlated with patient overall survival (OS). A separate group of 200 neoadjuvant-treated PDACs served as a validation cohort for further analysis. RESULTS: Among treatment-naïve PDACs, there was a moderate concordance between EUS imaging and postoperative pathology for tumor size (r = 0.726, P < .001) and AJCC 8th edition T-stage (r = 0.586, P < .001). In the setting of neoadjuvant therapy, a decrease in T-stage correlated with improved 3-year OS rates (50% vs 31%, P < .001). Through recursive partitioning, a cutoff of ≥47% tumor size reduction was also found to be associated with improved OS (67% vs 32%, P < .001). Improved OS using a ≥47% threshold was validated using a separate cohort of neoadjuvant-treated PDACs (72% vs 36%, P < .001). By multivariate analysis, a reduction in tumor size by ≥47% was an independent prognostic factor for improved OS (P = .007). CONCLUSIONS: The difference in tumor size between preoperative EUS imaging and postoperative pathology among neoadjuvant-treated PDAC patients is an important prognostic indicator and may guide subsequent chemotherapeutic management.

Comparison of quantitative internal and external measures of performance for trainees in cytopathology fellowships.

INTRODUCTION: Cytopathology fellowships need measures to assess performance of fellows. We sought to compare several internal quantitative assessment metrics in our fellowship with external metrics, such as performance on the American Society of Cytopathology (ASC) Progressive Evaluation of Competency (PEC) examination and United States Medical Licensing Examination (USMLE). METHODS: Quantitative parameters generated from our laboratory information system (LIS) on cytopathology fellows were evaluated over 6 years, including case volume and diagnostic discrepancies, in addition to ASC PEC and USMLE scores. For discrepancy reports, interpretations made by the fellow were compared with that of the cytopathologist, and classified as none (concordant), minor (<2-levels) or major (≥2-levels). RESULTS: We evaluated internal and external metrics on 13 fellows over 6 years. The program average diagnostic concordance rate was 89.9%, with an average major discrepancy rate of 1.5%, and an average monthly case volume of 260 cases. More fellows with above-average ASC PEC performance showed above-average concordant diagnoses and lower case volume, while below-average PEC scores were seen more often with higher major discrepancy rates. More fellows with above-average USMLE scores had higher case volumes, while low USMLE scores showed a trend towards higher major discrepancy rates. CONCLUSION: Our fellowship program has used a variety of internal and external measures of performance for cytopathology fellows. Although the findings show no statistically significant finding correlating performance, these quantitative parameters generated from our LIS were helpful to identify areas of improvement, facilitate comparison to peers, and provide case volume documentation.

Molecular alterations in Hürthle cell nodules and preoperative cancer risk.

Hürthle cell carcinoma (HCC) is a distinct type of thyroid cancer genetically characterized by DNA copy number alterations (CNA), typically of genome haploidization type (GH-type). However, whether CNA also occurs in benign Hürthle cell adenomas (HCA) or Hürthle cell hyperplastic nodules (HCHN), and have diagnostic impact in fine-needle aspiration (FNA) samples, remains unknown. To address these questions, we (1) analyzed 26 HCC, 24 HCA, and 8 HCHN tissues for CNA and other mutations using ThyroSeq v3 (TSv3) next-generation sequencing panel, and (2) determined cancer rate in 111 FNA samples with CNA and known surgical outcome. We identified CNA, more often of the GH-type, in 81% of HCC and in 38% HCA, but not in HCHN. Among four HCC with distant metastasis, all had CNA and three TERT mutations. Overall, positive TSv3 results were obtained in 24 (92%) HCC, including all with ATA high risk of recurrence or metastasis. Among 111 FNA cases with CNA, 38 (34%) were malignant and 73 (66%) benign. A significant correlation between cancer rate and nodule size was observed, particularly among cases with GH-type CNA, where every additional centimeter of nodule size increased the malignancy odds by 1.9 (95% CI 1.3-2.7; P = 0.001). In summary, the results of this study demonstrate that CNA characteristic of HCC also occur in HCA, although with lower frequency, and probability of cancer in nodules with CNA increases with nodule size. Detection of CNA, in conjunction with other mutations and nodule size, is helpful in predicting malignancy in thyroid nodules.

Impact of molecular testing on detecting mimics of oncocytic neoplasms in thyroid fine-needle aspirates diagnosed as follicular neoplasm of Hürthle cell (oncocytic) type.

BACKGROUND: Some thyroid nodules cytologically presenting as follicular neoplasm, Hürthle cell (Oncocytic) type (FNHCT), are not oncocytic tumors and represent autonomously functioning thyroid nodules (AFTNs) with TSHR, GNAS, and EZH1 mutations or oncocytic metaplasia. A to be defined subset of FNHCT harbors genome haploidisation-type DNA copy number alterations (GH-CNA). Molecular profiling of FNHCT may distinguish oncocytic neoplasms from its mimics. METHODS: Consecutive fine-needle aspirates of 180 thyroid nodules over 37 months diagnosed as FNHCT and tested by ThyroSeq v3 were identified. Histologic follow-up was available for 79 of 180 nodules (44%). RESULTS: No molecular alterations were found in 76 of 180 nodules (42%), of which 15 were resected (oncocytic metaplasia, n = 7; follicular oncocytic adenoma, n = 8). Of nodules followed without surgery, 17 of 101 (17%) showed TSHR, EZH1, and GNAS mutations of AFTNs. Papillary thyroid carcinoma was identified by BRAF V600E (n = 2) and hyalinizing trabecular adenoma by PAX8-GLIS3 (n = 1). GH-CNA alone was detected in 42 of 180 FNHCT nodules (23%), of which 29 were resected and histologically diagnosed as follicular oncocytic neoplasms. All remaining resected nodules were histologically proven oncocytic neoplasms: 1) RAS-like alterations without GH-CNA (n = 25) and 2) TERT and/or TP53 mutations co-occurring with GH-CNA (n = 6), including anaplastic thyroid carcinoma arising from follicular oncocytic carcinoma with TP53, TERT mutations with GH-CNA (n = 2). CONCLUSIONS: A proportion of FNHCT nodules are AFTNs and oncocytic metaplasias, which can be suspected based on characteristic mutations or lack of alterations on molecular testing. Among resected FNHCTs, GH-CNAs characterize approximately half of histologically confirmed follicular oncocytic neoplasms.

Thyroid cytology smear slides: An untapped resource for ThyroSeq testing.

BACKGROUND: Molecular testing of thyroid nodules with indeterminate fine-needle aspiration (FNA) cytology is commonly used to guide patient management and is typically performed on freshly collected FNA samples. In this study, the authors evaluated the performance of the ThyroSeq test in cytology smear slides. METHODS: Air-dried Diff-Quik (DQ)-stained and alcohol-fixed Papanicolaou (Pap)-stained smears were used to determine required cellularity and sensitivity of mutation detection and to compare ThyroSeq v3 Genomic Classifier (GC) results obtained in cytology smears and fresh FNA samples from the same nodules. RESULTS: ThyroSeq testing of 31 cytology smears revealed that 25 smears (81%) were adequate for ThyroSeq analysis, including 14 Pap-stained smears (100%) and 11 DQ-stained smears (65%), whereas 6 DQ-stained smears (35%) failed RNA sequencing. The overall accuracy for detecting molecular alterations was 98%, with 100% concordance for mutations and gene expression alterations, 96% concordance for fusions, and 94% concordance for copy number alterations. Cytology smears were adequate for ThyroSeq analysis when at least 200 to 300 cells were present in 1 to 3 slides. ThyroSeq detected all studied mutations down to 5% allele frequency and BRAF mutations down to 1% allele frequency. Testing of smears yielded a positive ThyroSeq GC result in all nodules originally classified as positive. CONCLUSIONS: Thyroid FNA cytology smear slides with adequate cellularity can be successfully used for ThyroSeq GC testing in approximately 80% of cases, with an even higher success rate in Pap-stained smears. Compared with FNA samples collected into preservative solution, 94% to 100% of different genetic alterations could be accurately detected in smears, validating cytology smears as an alternative for ThyroSeq testing in patients with indeterminate thyroid cytology.

Molecular testing and thyroid nodule management in North America.

The incidence of thyroid cancer is rising for a variety of reasons. At the same time, the nomenclature revision of non-invasive encapsulated follicular-variant PTC to noninvasive follicular neoplasm with papillary-like nuclear features (NIFTP) has modified the incidence of thyroid cancer. Given that thyroid neoplasia is a molecular event, it is important for the thyroid physician to evaluate each patient systematically. Most thyroid cancers are sporadic; however, some are familial and may be associated with syndromes with genetic implications. Advances in radiologic imaging have made ultrasonography a near equivalent of gross examination. The American College of Radiology Thyroid Imaging, Reporting and Data System (ACR TI-RADS) classifies nodules from TR1 to TR5 and is valuable in determining which patients should be guided toward fine-needle aspiration (FNA) sampling. While FNA procedures and processing may be varied, the key elements are cytologic diagnosis and collection of samples for potential molecular testing. The Bethesda System for Reporting Thyroid Cytology (BSRTC) is commonly used and categorizes each FNA specimen into one of six diagnoses. The indeterminate diagnoses with risk of malignancy (ROM) ranging from 10-75% comprise approximately 30% of thyroid FNA cases and for these, molecular testing is beneficial. In North America, the two most common molecular platforms are Veracyte Afirma GSC and ThyroSeq v3. Both panels cover an extensive array of genomic alterations associated with thyroid neoplasia and a negative result from either test effectively refines the ROM of an Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (AUS/FLUS) or Follicular Neoplasm/Suspicious for a Follicular Neoplasm (FN/SFN) diagnosis to 3-4%. Given that the refined ROMs are comparable to that of a Benign BSRTC diagnosis, these patients are recommended for observation of their nodules. However, differences exist in the implication of Afirma GSC-Suspicious and ThyroSeq v3-Positive molecular results with regard to the probability of cancer. For either test, the molecular test result should be integrated with other clinical parameters to determine if surgery is indicated and, if so, the extent of surgery.

The Clinical Utility of Molecular Testing in the Management of Thyroid Follicular Neoplasms (Bethesda IV Nodules).

OBJECTIVE: FN present a management quandary as they are often benign but may also be aggressive TC. Consensus recommendations have historically advised thyroidectomy for definitive diagnosis. Although MT have robust benefit in hypothetical cost analyses, under current management guidelines a real-time study of their clinical utility in FN is awaited. We investigate if MT use for FN directs appropriate thyroidectomy for TC while triaging to surveillance nodules that are likely benign. METHODS: Data were analyzed for 389 consecutive patients managed from 11/14 to 9/19 for 405 FN, excluding oncocytic neoplasms. TC was defined as same-nodule histologic malignancy. When obtained, MT was performed using ThyroSeq (TS) v2 or 3. RESULTS: With a mean nodule size of 2.7 ±â€Š1.3 cm, MT was used in 89% and was positive in 39%. When MT was positive, thyroidectomy was more often utilized (91% v. MT- 27%; P < 0.001) and more likely for histologic TC (70% vs 16%, P < 0.001). With preoperative MT, all American Thyroid Association intermediate, high-risk, and medullary TC were positive whereas all MT- malignancies were low-risk. With TSv3, ultrasound surveillance was more likely for MT- FN (90% vs TSv2 65%, P < 0.001), and occurred for a total of 174 MT- FN. With mean follow-up of 24.6 months, 82% remained stable in size. CONCLUSIONS: MT use for FN increased the surgical yield of cancer by 4-fold, identified all potentially aggressive malignancies, and allowed apparently safe nonoperative surveillance for >80% of MT-negative patients. Thyroid nodule MT optimizes patient outcomes sufficiently to justify its incorporation into routine practice.