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Fine-needle-aspiration-cytology (FNAC) is safe and cost-effective procedure for evaluating thyroid nodules. The non-negligible rate of indeterminate cytology (ITN), warrants diagnostic surgery for histological assessment, in some cases. Two recent studies (from Europe and the U.S.) reported that the clinical behavior of a histologically proven thyroid cancer (TC) varies according to its pre-surgical FNAC results. Despite differences in study design, inclusion criteria, and the use of different cytology classification systems (Italian and Bethesda), the overall results were comparable. In order to further discuss these results and to provide additional perspective on the topic, the senior authors of the two studies invited other thyroid experts and cytologists not involved in the previous studies to participate in the present commentary. The strong, consistent clinical message that emerges, especially regarding PTC, is that TC with an initial diagnosis of ITN has a less aggressive clinical presentation, lower rates of: i) lymph-node metastasis; ii) more aggressive variants; iii) BRAFV600E mutations, as compared with DTC with an initial diagnosis of "suspicious for malignancy" or "malignant". These results were consistent in both studies and strongly point toward a more indolent clinical phenotype of DTC with a preoperative diagnosis of ITN as opposed to suspicious for malignancy or malignant. Further understanding the clinical implications of these data appears of clinical relevance and will be discussed from both the endocrinologist and cytologist point of view. The here overviewed data provide the foundation for beginning to examine the impact of less aggressive therapies for TC with an initial ITN diagnosis., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com. See the journal About page for additional terms.)

Background: Papillary renal neoplasm with reverse polarity is a recently recognized low-grade neoplasm with a favorable prognosis. To date, its cytologic features have not been well documented., Methods: Two patients with papillary renal neoplasm with reverse polarity sampled by fine needle aspiration and core needle biopsy are described, one of whom is under active surveillance without clinical progression and the other is alive and well 16 years after partial nephrectomy., Results: The cytologic features included a mix of papillae and dispersed cells with abundant oncocytic cytoplasm and round, bland nuclei apically displaced away from the papillary core. Immunohistochemistry showed positive staining for GATA3 in both cases. Molecular studies on one of the cases showed a KRAS p.G12V mutation., Conclusions: The cytologic features of this distinctive, indolent neoplasm are important to recognize because patients with papillary renal neoplasm with reverse polarity may be excellent candidates for partial nephrectomy or even active surveillance., (© 2024 American Cancer Society.)

Background: Leptomeningeal metastases occur across multiple solid and lymphoid cancers, and patients typically undergo cytopathologic assessment of cerebrospinal fluid (CSF) in this setting. For patients diagnosed with metastatic cancer, the detection of actionable somatic mutations in CSF can provide clinically valuable information for treatment without the need for additional tissue collection., Methods: The authors validated a targeted next-generation sequencing assay for the detection of somatic variants in cancer (OncoPanel) on cell-free DNA (cfDNA) isolated from archival CSF specimens in a cohort of 25 patients who had undergone molecular testing of a prior tumor specimen., Results: CSF storage time and volume had no impact on cfDNA concentration or mean target coverage of the assay. Previously identified somatic variants in CSF cfDNA were detected in 88%, 50%, and 27% of specimens diagnosed cytologically as positive, suspicious/atypical, and negative for malignancy, respectively. Somatic variants were identified in 81% of CSF specimens from patients who had leptomeningeal enhancement on magnetic resonance imaging compared with 31% from patients without such enhancement., Conclusions: These data highlight the stability of cfDNA in CSF, which allows for cytopathologic evaluation before triage for next-generation sequencing assays. For a subset of cases in which clinical suspicion is high but cytologic or radiographic studies are inconclusive, the detection of pathogenic somatic variants in CSF cfDNA may aid in the diagnosis of leptomeningeal metastases., (© 2023 American Cancer Society.)

Introduction: Sclerosing Mucoepidermoid Carcinoma with Eosinophilia (SMECE) of the thyroid is an extremely rare tumor that exhibits unique histologic characteristics and is nearly always associated with lymphocytic thyroiditis (LT). However, the cytomorphologic and clinicopathologic characteristics of SMECE have only been described in rare case reports., Materials and Methods: Authors' institution laboratory information systems were searched for records of SMECE between 2012 and 2023. Literature review was performed using keywords "Sclerosing mucoepidermoid carcinoma with eosinophilia", "thyroid", and "cytopathology" to search through institution electronic library databases for relevant articles., Results: A total of 19 cases were identified, 3 unpublished in the authors' archives and 16 in the literature which had fine needle aspiration (FNA) material or cytologic features available for review, and were comprised of 3 males and 16 females. The common cytomorphologic characteristics of SMECE included fragments or loose clusters of intermediate-type epidermoid cells in a background of prominent LT and eosinophils. Overt keratinization, mucinous cells, and extracellular mucin were not commonly encountered, resulting in diagnostic challenges, especially if eosinophils associated with epithelial cell clusters were rare. The cases were reported as "Nondiagnostic" (1 case), "Atypia of Undetermined Significance" (4 cases), "Suspicious for Malignancy" (3 case), or "Malignant" (11 cases)., Conclusions: The clinical course of SMECE of the thyroid varied and distinct cytomorphologic characteristics in a subset of patients who experienced aggressive disease raises the possibility of different prognostic grades. Cases with keratinized squamous cells and necrosis mimic anaplastic (undifferentiated) thyroid carcinoma, but the clinical history and radiologic findings can be helpful to exclude this diagnosis., (Copyright © 2023 American Society of Cytopathology. Published by Elsevier Inc. All rights reserved.)

Introduction: Benign (B) follicular lesions of the thyroid are among the most encountered specimens on fine needle aspiration (FNA). Although FNA and The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) remain highly accurate, minimally invasive and robust tools in triaging thyroid nodules, false positive (FP) diagnoses may still occur. Endocrine-type degenerative atypia can cause diagnoses of suspicious for malignancy (SFM) or malignant (M), resulting in overtreatment and exposure to undue surgical risk in patients., Materials and Methods: We performed a multi-institutional retrospective clinicopathologic correlation of benign thyroid nodules with degenerative atypia on FNA. Review of cytologic material was conducted to identify potential cytomorphologic features which may have prompted these diagnoses., Results: Among 342 patients with benign thyroid nodules harboring degenerative atypia, 123 had available preceding FNA cytopathology. TBSRTC nondiagnostic, B, atypia of undetermined significance, follicular neoplasm, SFM, and M, comprised 3.3%, 49.6%, 30.1%, 13.0%, 2.4%, and 1.6% of cases. Among patients with FP diagnoses (SFM and M), 100% underwent total thyroidectomy, and 40.0% underwent additional neck lymph node dissections. Among remaining patients, 61.0%, 39.0%, and 0% underwent lobectomy, thyroidectomy, and lymph node dissection. The number of patients who underwent total thyroidectomy was significantly different (P = 0.03) between those with FP nodules and those without., Conclusions: We demonstrate that 4.1% of nodules harboring endocrine-type degenerative atypia may be given FP diagnoses on initial FNA. Such atypia may be indistinguishable from that of Graves' Disease, dyshormonogenic goiter, and radiation therapy. FP diagnoses of degenerative atypia can expose patients to undue surgical procedures and risks., (Copyright © 2023 American Society of Cytopathology. Published by Elsevier Inc. All rights reserved.)

Background: For cytologically benign thyroid nodules with very low to intermediate suspicion ultrasound patterns, optimal ultrasound follow-up intervals and outcomes of discontinuing follow-up are unclear. Methods: Ovid MEDLINE, Embase, and Cochrane Central were searched through August 2022 for studies comparing different ultrasound follow-up intervals and discontinuation versus continuation of ultrasound follow-up. The population was patients with cytologically benign thyroid nodules and very low to intermediate suspicion ultrasound patterns, and the primary outcome was missed thyroid cancers. Utilizing a scoping approach, we also included studies that were not restricted to very low to intermediate suspicion ultrasound patterns or evaluated additional outcomes such as thyroid cancer-related mortality rate, nodule growth, and subsequent procedures. Quality assessment was performed, and evidence was synthesized qualitatively. Results: One retrospective cohort study ( n  = 1254; 1819 nodules) compared different first follow-up ultrasound intervals for cytologically benign thyroid nodules. There was no difference between >4- versus 1- to 2-year intervals to first follow-up ultrasound in the likelihood of malignancy (0.4% [1/223] vs. 0.3% [2/715]), and no cancer-related deaths occurred. Follow-up ultrasound at >4 years was associated with increased likelihood of ≥50% nodule growth (35.0% [78/223] vs. 15.1% [108/715]), repeat fine needle aspiration (19.3% [43/223] vs. 5.6% [40/715]), and thyroidectomy (4.0% [9/223] vs. 0.8% [6/715]). The study did not describe ultrasound patterns or control for confounders, and analyses were based on interval to first follow-up ultrasound only. Other methodological limitations were not controlling for variability in follow-up duration and unclear attrition. The certainty of evidence was very low. No study compared discontinuation of ultrasound follow-up versus continuation. Conclusions: This scoping review found that evidence comparing different ultrasound follow-up intervals in patients with benign thyroid nodules is limited to one observational study, but suggests that the subsequent development of thyroid malignancies is very uncommon regardless of follow-up interval. Longer follow-up may be associated with more repeat biopsies and thyroidectomies, which could be related to more interval nodule growth that meets thresholds for further evaluation. Research is needed to clarify optimal ultrasound follow-up intervals for low to intermediate suspicion cytologically benign thyroid nodules and outcomes of discontinuing ultrasound follow-up for very low suspicion nodules.

Background: The burden of the COVID-19 pandemic is often enumerated in lives lost, but the strain on health care resources and mobility limitations contributed to the burden of non-COVID related disease. In this study, we evaluated the impact of the pandemic through a time series review of cytology samples., Methods: Pathology reports for all cytology specimens received from January 2019 through April 2021 at our institution were reviewed. Time series analysis was performed using moving averages, time trend analysis, cross-correlation, and tests of homogeneity., Results: During the first peak of the pandemic (March-June 2020), breakpoint analysis showed a downward shift in the number of gynecologic (-89.4%) and non-gynecologic (-70.4%) cytology specimens within a week of declaration of an emergency. Cross-correlation analysis showed a relationship between sample numbers and COVID-19 cases during the initial phase of the pandemic (April-June 2020). During the second surge (October 2020-April 2021), despite the higher incidence of COVID-19, there was a smaller impact on cytology samples (-20.1% and - 24.8% for gynecologic and non-gynecologic samples, respectively). During the first 3 months of the pandemic, 154 fewer malignant cases were identified compared with the prior year. Although specimen numbers slowly returned to baseline following the first wave of the pandemic, the earlier decline in malignant diagnoses was not offset during the study period., Conclusions: The deleterious effects of COVID-19 extend beyond direct mortality attributed to the disease. The significant decrease in diagnostic cytology specimens during this period has profound implications including delayed care and missed disease., (© 2022 American Cancer Society.)

Thyroid nodules are common, usually asymptomatic, and often pose minimal risk to the affected patient. However, 10-15% prove malignant and serve as the rationale for diagnostic assessment. Safely identifying and treating a relevant thyroid cancer through a cost-effective process is the primary goal of the treating practitioner. Ultrasound is the principal means of initial nodule assessment and should be performed when any thyroid nodule is suspected. Fine-needle aspiration provides further cytological determination of benign or malignant disease and is generally applied to nodules larger than 1-2 cm in diameter, on the basis of holistic risk assessment. The Bethesda System for Reporting Thyroid Cytopathology provides standardised terminology, which enhances communication among health-care providers and patients. Benign cytology is highly accurate, whereas indeterminate cytology could benefit from further application of molecular testing. The ultimate goal of diagnostic assessment of thyroid nodules is to accurately identify malignancy while avoiding overtreatment. Low-risk thyroid nodules can be safely monitored in many patients with minimal diagnostic intervention., Competing Interests: Declaration of interests EKA has received research support from Asuragen and Veracyte, and consulting fees from Asuragen, Veracyte, and Roche Diagnostics. EKA was a coauthor of the 2015 clinical guidelines for the diagnosis and management of thyroid nodules and thyroid cancer, published by the American Thyroid Association, for which he received no payment. EKA is a member of the editorial board for the Journal of Clinical Endocrinology & Metabolism, for which he received no payment. ESC has received royalty payments from Elsevier and Springer; he holds a US patent (number 6 468 208B1) for computerised performance evaluation of cytologists, for which he received no payment. ESC is currently a member of the American Thyroid Association clinical guideline taskforce updating national guidelines for thyroid nodule diagnosis and management, for which he received no payment. ESC is a member of the awards committee for the American Society of Cytopathology and is on the editorial review boards for Cancer Cytopathology, Journal of the American Society of Cytopathology, and Endocrine Pathology, for which he received no payment. ESC was an Associate Editor for Acta Cytologica., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Thyroid nodules with atypia of undetermined significance (AUS) are challenging to manage because of their intermediate risk of malignancy. Subclassification of atypia can refine malignancy risk in adult AUS nodules but has not been evaluated in children., Methods: This was a retrospective cohort study of pediatric patients (<19 years old) who underwent fine-needle aspiration (FNA) of a thyroid nodule with resulting AUS cytology. Atypia was subclassified as nuclear only, architectural only, nuclear and architectural, or oncocytic. The primary outcome was the association between atypia subtype and malignancy. A secondary outcome was the association of atypia subtype with repeat FNA cytology., Results: Sixty-eight AUS nodules in 61 patients were analyzed. The median age at FNA was 16.2 years (range, 9.8-18.9 years). Twenty-four nodules (35%) were malignant. Nuclear atypia only was present in 17 nodules (25%), architectural atypia only was present in 27 nodules (40%), nuclear and architectural atypia was present in 20 nodules (29%), and predominantly oncocytic features were present in 4 nodules (6%). The presence of nuclear atypia was associated with a significantly increased rate of malignancy (22 of 37 [59%] vs 2 of 31 [6.5%]; P < .001), whereas architectural atypia was not associated with malignancy (P = .8). Repeat FNA was performed in 42 of 68 nodules (62%). In nodules with initial nuclear and architectural atypia, benign repeat cytology had a high false-negative rate (3 of 6; 50%)., Conclusions: Pediatric AUS nodules with nuclear atypia have a high rate of malignancy, but architectural atypia is not associated with malignancy. In nodules with nuclear atypia, repeat FNA may inform clinical decisions regarding the need for resection. In the absence of suspicious clinical features, nodules without nuclear atypia might be considered for observation rather than resection or repeat FNA., (© 2022 American Cancer Society.)

Introduction: Cytopathology has well-defined and objective quality metrics for monitoring the performance of cytopathologists (CPs) and cytotechnologists (CTs). We transformed these metrics into dashboards for real-time visualization and on-demand feedback., Methods: Dashboards were constructed with data from the previous 10 calendar years using the software Tableau. The dashboards for CPs were designed to display 2 gynecologic metrics and 1 nongynecologic metric: the ASCUS:SIL ratio, the percentage of high-risk human papillomavirus (HPV)-positive ASCUS interpretations (HPV+ ASCUS rate), and the proportion of AUS/FLUS thyroid interpretations. CT dashboards were designed to include these plus 2 others: the percentage of Papanicolaou tests referred for CP review and the percentage of Papanicolaou tests interpreted as unsatisfactory. Established professional benchmarks or standard deviations were used to set color-coded "goal," "borderline," and "attention" zones., Results: Personal dashboards were successfully developed and implemented for CPs and CTs in the laboratory, with results that are automatically updated every week, requiring minimal curation. Each CP and CT has a unique link that allows them access to their results at any time. Color-coded displays show the individual their quality metrics over the past 10 years, with a snapshot of data from the past 3 months. The laboratory director has a unique link that allows the director access to results for each individual and the laboratory in aggregate., Conclusions: Personalized dashboards enable individuals to access their performance metrics on demand and examine recent performance as well as patterns over time. This facilitates self-motivation to improve performance and adhere to professional benchmarks., (Copyright © 2021 American Society of Cytopathology. Published by Elsevier Inc. All rights reserved.)

Background: Distinctive rounded structures termed spherules have been observed in thyroid fine-needle aspiration (FNA) samples. Although they are often small and interpreted as microfollicles, spherules are notable for the even spacing of the follicular cells along the perimeter of the structure. Because they have an orderly architectural arrangement, it has been hypothesized that spherules are benign and do not carry the same risk of malignancy that traditional microfollicles do. The aim of this study was to identify the clinical significance and histopathologic correlate of spherules., Methods: Thyroid FNAs (n = 637) with an interpretation of atypia of undetermined significance (AUS) were reviewed for the presence of spherules, which were defined as small follicles with a rounded, smooth, sharply defined outer contour, evenly spaced nuclei, and a 3-dimensional appearance. Cases were included if spherules accounted for >50% of follicular cell arrangements. Clinical, histopathologic, molecular, and sonographic follow-up data were obtained., Results: Twenty-five spherule cases were identified, and they represented 3.9% of all AUS cases reviewed. All 24 cases with follow-up had a benign outcome. Eleven were tested with the Afirma gene expression classifier; 8 were benign according to the gene expression classifier, and 3 were suspicious but histologically benign after surgical resection. Four additional cases were histologically benign after surgery. Five patients had repeat benign cytology. Four patients had repeat stable ultrasound findings., Conclusions: Thyroid nodules diagnosed as AUS, if composed predominantly of spherules, are associated with a benign outcome. Recognizing this distinctive cytomorphologic finding may help to reduce the number of FNAs interpreted as AUS and save patients from unnecessary additional testing and surgery., (© 2019 American Cancer Society.)

Introduction: Dissemination of tumor to the leptomeninges, subarachnoid space, and cerebrospinal fluid (CSF) is termed leptomeningeal metastasis (LM) and occurs in approximately 5% of patients with solid tumors. LM is associated with dismal clinical prognosis, and routine cytologic and radiologic methods for diagnosing LM have limited sensitivity. The CellSearch immunomagnetic rare cell capture assay is FDA-approved to detect circulating tumor cells (CTCs) in peripheral blood, but whether it may have a role in identifying CSF CTCs is still unclear., Material and Methods: CSF specimens from 20 patients with clinically suspected solid tumor LM collected from 2 institutions between October 2016 and January 2019 were evaluated with routine CSF cytology and underwent concurrent CTC testing with the CellSearch assay (Menarini-Silicon Biosystems, Huntingdon Valley, PA). The results of CTC testing were compared to routine CSF cytology and radiologic studies for detecting LM., Results: The CellSearch assay achieved a sensitivity of 88.9% and specificity of 100% for detecting LM (using a threshold of 1 CTC/mL of CSF as the definition of a positive CTC result). One patient with negative CSF cytology but positive CTCs developed positive cytology 37 days later., Conclusions: In this proof-of-principle pilot study, we demonstrate that the CellSearch assay can be successfully integrated with the routine CSF cytologic workflow to aid in the diagnosis of solid tumor LM. Importantly, CTCs detected by this rare cell capture assay are found in a subset of patients with non-positive routine CSF cytology, which may have significant implications for patient management., (Copyright © 2020 American Society of Cytopathology. Published by Elsevier Inc. All rights reserved.)

Context: Assessing thyroid nodules for malignancy is complex. The impact of patient and nodule factors on cancer evaluation is uncertain., Objectives: To determine precise estimates of cancer risk associated with clinical and sonographic variables obtained during thyroid nodule assessment., Design: Analysis of consecutive adult patients evaluated with ultrasound-guided fine-needle aspiration for a thyroid nodule ≥1 cm between 1995 and 2017. Demographics, nodule sonographic appearance, and pathologic findings were collected., Main Outcome Measures: Estimated risk for thyroid nodule malignancy for patient and sonographic variables using mixed-effect logistic regression., Results: In 9967 patients [84% women, median age 53 years (range 18 to 95)], thyroid cancer was confirmed in 1974 of 20,001 thyroid nodules (9.9%). Significant ORs for malignancy were demonstrated for patient age <52 years [OR: 1.82, 95% CI (1.63 to 2.05), P < 0.0001], male sex [OR: 1.68 (1.45 to 1.93), P < 0.0001], nodule size [OR: 1.30 (1.14 to 1.49) for 20 to 19 mm, OR: 1.59 (1.34 to 1.88) for 30 to 39 mm, and OR: 1.71 (1.43 to 2.04) for ≥40 mm compared with 10 to 19 mm, P < 0.0001 for all], cystic content [OR: 0.43 (0.37 to 0.50) for 25% to 75% cystic and OR: 0.21 (0.15 to 0.28) for >75% compared with predominantly solid, P < 0.0001 for both], and the presence of additional nodules ≥1 cm [OR: 0.69 (0.60 to 0.79) for two nodules, OR: 0.41 (0.34 to 0.49) for three nodules, and OR: 0.19 (0.16 to 0.22) for greater than or equal to four nodules compared with one nodule, P < 0.0001 for all]. A free online calculator was constructed to provide malignancy-risk estimates based on these variables., Conclusions: Patient and nodule characteristics enable more precise thyroid nodule risk assessment. These variables are obtained during routine initial thyroid nodule evaluation and provide new insights into individualized thyroid nodule care., (Copyright © 2019 Endocrine Society.)

Introduction: The Afirma® Xpression Atlas (XA) detects gene variants and fusions in thyroid nodule FNA samples from a curated panel of 511 genes using whole-transcriptome RNA-sequencing. Its intended use is among cytologically indeterminate nodules that are Afirma GSC suspicious, Bethesda V/VI nodules, or known thyroid metastases. Here we report its analytical and clinical validation. Methods: DNA and RNA were purified from the same sample across 943 blinded FNAs and compared by multiple methodologies, including whole-transcriptome RNA-seq, targeted RNA-seq, and targeted DNA-seq. An additional 695 blinded FNAs were used to define performance for fusions between whole-transcriptome RNA-seq and targeted RNA-seq. We quantified the reproducibility of the whole-transcriptome RNA-seq assay across laboratories and reagent lots. Finally, variants and fusions were compared to histopathology results. Results: Of variants detected in DNA at 5 or 20% variant allele frequency, 74 and 88% were also detected by XA, respectively. XA variant detection was 89% when compared to an alternative RNA-based detection method. Low levels of expression of the DNA allele carrying the variant, compared with the wild-type allele, was found in some variants not detected by XA. 82% of gene fusions detected in a targeted RNA fusion assay were detected by XA. Conversely, nearly all variants or fusions detected by XA were confirmed by an alternative method. Analytical validation studies demonstrated high intra-plate reproducibility (89%-94%), inter-plate reproducibility (86-91%), and inter-lab accuracy (90%). Multiple variants and fusions previously described across the spectrum of thyroid cancers were identified by XA, including some with approved or investigational targeted therapies. Among 190 Bethesda III/IV nodules, the sensitivity of XA as a standalone test was 49%. Conclusion: When the Afirma Genomic Sequencing Classifier (GSC) is used first among Bethesda III/IV nodules as a rule-out test, XA supplements genomic insight among those that are GSC suspicious. Our data clinically and analytically validate XA for use among GSC suspicious, or Bethesda V/VI nodules. Genomic information provided by XA may inform clinical decision-making with precision medicine insights across a broad range of FNA sample types encountered in the care of patients with thyroid nodules and thyroid cancer., (Copyright © 2019 Angell, Wirth, Cabanillas, Shindo, Cibas, Babiarz, Hao, Kim, Walsh, Huang, Kloos, Kennedy and Waguespack.)

Background: The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) is used to interpret fine-needle aspiration (FNA) cytology of thyroid nodules in children and adults. Nodule management is guided by the implied malignancy risk of each cytological category, which has been derived from adult populations. Whether these implied risks are applicable to pediatric thyroid nodules remains uncertain. We compared malignancy rates between pediatric and adult thyroid nodules within each cytological category. Methods: We evaluated consecutive thyroid nodules ≥1 cm that underwent FNA at the Boston Children's Hospital and Brigham and Women's Hospital from 1998 to 2016. All cytology was interpreted by a single cytopathology group according to the BSRTC. Malignancy rates were compared between pediatric (<19 years) and adult (≥19 years) patients. Results: Four hundred thirty pediatric thyroid nodules and 13,415 adult nodules were analyzed. Pediatric nodules were more likely to be malignant than adult nodules (19% vs. 12%, p  = 0.0002). Within cytological categories, malignancy rates were higher in pediatric nodules than in adult nodules that were cytologically nondiagnostic (11% vs. 4%, p  = 0.03), atypia of undetermined significance (AUS; 44% vs. 22%, p  = 0.004), or suspicious for follicular neoplasm (SFN; 71% vs. 28%, p  = 0.001). There were no significant differences between children and adults in the types of thyroid cancers diagnosed in these cytological categories. Among cytologically benign nodules, the difference in malignancy rates was statistically significant but clinically minimal (0.7% vs. 1%, p  = 0.001). Malignancy rates did not differ between children and adults among nodules with cytology suspicious for papillary carcinoma (73% vs. 68%, p  = 0.67) or positive for malignancy (97% vs. 95%, p  = 1). Among the subset of nodules that were resected, the malignancy rate was higher in children than in adults only in nodules that were SFN (71% vs. 36%, p  = 0.007). Conclusions: Among thyroid nodules that are cytologically AUS, SFN, or nondiagnostic, malignancy rates are higher in children than in adults. These discrepancies likely represent true differences in malignancy risk between pediatric and adult patients, rather than differences in cytological interpretation. Our findings provide pediatric-specific data to inform the optimal management of thyroid nodules in children, which may differ from that of adult nodules with equivalent cytology.

Background: For thyroid nodules with indeterminate cytology, the Afirma Gene Expression Classifier (GEC) identified benign nodules to reduce diagnostic surgery, though many nodules classified as suspicious still proved histopathologically benign. The current Afirma Genomic Sequencing Classifier (GSC) demonstrates improved specificity, suggesting more nodules will have a benign result (benign call rate [BCR]), but independent data are needed to confirm this in clinical practice. Methods: Retrospective analysis was performed of all Bethesda III or IV cytology thyroid nodules ≥1 cm tested with GEC (between January 1, 2011, and July 19, 2017) or GSC (between July 20, 2017, and August 27, 2018) at the authors' institution. Afirma testing was not performed reflectively for all nodules with Bethesda III or IV cytology, but rather was applied based on physician-patient decision making. Demographic, sonographic, and cytologic data were collected. The BCR for GEC- versus GSC-tested nodules was compared and further stratified by Bethesda classifications. Results: The study evaluated 600 nodules in 563 patients tested with either GEC ( n  = 486) or GSC ( n  = 114). The BCR was 233/486 (47.9%) for the GEC compared to 75/114 (65.8%) for the GSC ( p  = 0.0006). Hürthle-cell cytology was present in 99/486 (20.4%) nodules in the GEC group compared to 31/114 (27.2%) nodules in the GSC group ( p  = 0.28). The GSC BCR was significantly higher than the GEC BCR for Bethesda III nodules characterized by Hürthle cells ( p  = 0.006), but the BCRs were similar for nodules with architectural or cytologic atypia. In Bethesda IV nodules suspicious for follicular neoplasm, BCR for the GEC and GSC were similar ( p  = 0.68), but for cytology suspicious for Hürthle-cell neoplasm, the GSC BCR was 68.2% (15/22) compared to the GEC BCR of 16.4% (10/61; p  < 0.0001). Positive predictive value in resected nodules with a suspicious result was 16/32 (50%) for GSC nodules and 75/221 (33.9%) for GEC nodules ( p  = 0.1). Conclusions: The higher BCR for the GSC compared to the GEC for indeterminate thyroid nodules, predominantly among nodules with Hürthle-cell cytology, will likely lead to further reduction in surgical management.

Context: The impact of Hashimoto thyroiditis (HT) on the risk of thyroid cancer and its accurate detection remains unclear. The presence of a chronic lymphocytic infiltration imparts a logical mechanism potentially altering neoplastic transformation, while also influencing the accuracy of diagnostic evaluation., Methods: We performed a prospective, cohort analysis of 9851 consecutive patients with 21,397 nodules ≥1 cm who underwent nodule evaluation between 1995 and 2017. The definition of HT included (i) elevated thyroid peroxidase antibody (TPOAb) level and/or (ii) findings of diffuse heterogeneity on ultrasound, and/or (iii) the finding of diffuse lymphocytic thyroiditis on histopathology. The impact of HT on the distribution of cytology and, ultimately, on malignancy risk was determined., Results: A total of 2651 patients (27%) were diagnosed with HT, and 3895 HT nodules and 10,168 non-HT nodules were biopsied. The prevalence of indeterminate and malignant cytology was higher in the HT vs non-HT group (indeterminate: 26.3% vs 21.8%, respectively, P < 0.001; malignant: 10.0% vs 6.4%, respectively, P < 0.001). Ultimately, the risk of any nodule proving malignant was significantly elevated in the setting of HT (relative risk, 1.6; 95% CI, 1.44 to 1.79; P < 0.001), and was maintained when patients with solitary or multiple nodules were analyzed separately (HT vs non-HT: 24.5% vs 16.3% solitary; 22.1% vs 15.4% multinodular; P < 0.01)., Conclusion: HT increases the risk of thyroid malignancy in any patient presenting for nodule evaluation. Diffuse sonographic heterogeneity and/or TPOAb positivity should be used for risk assessment at time of evaluation.

The newly introduced pathologic diagnosis of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) will result in less bilateral thyroid surgery as well as deescalation in T4 suppressive and radioactive iodine treatment. Although, NIFTP is a nonmalignant lesion that has nuclear features of some papillary malignancies, the challenge for the surgeon is to identify a lesion as possibly NIFTP before the pathologic diagnosis. NIFTP, due to its reduction of overall rates of malignancy, will result in the initial surgical pendulum swinging toward lobectomy instead of initial total thyroidectomy. This American Head and Neck Society endocrine section consensus statement is intended to inform preoperative evaluation to attempt to identify those patients whose final pathology report may ultimately harbor NIFTP and can be offered a conservative surgical plan to assist in cost-effective, optimal management of patients with NIFTP., (© 2018 The Authors. Head & Neck Published by Wiley Periodicals, Inc.)

Context: Most pediatric thyroid nodules are cytologically benign, but few data exist to guide treatment., Objective: To describe the natural history and outcomes of cytologically benign, pediatric thyroid nodules., Design: Cohort study., Setting: Multidisciplinary thyroid clinic at an academic medical center., Patients: Consecutive pediatric patients (≤18 years old) with cytologically benign thyroid nodules evaluated between 1998 and 2016., Results: Cytologically benign nodules (N = 237) in 181 patients were followed by ultrasound (median follow-up, 3.4 years; range, 0.5 to 13.9 years) or to resection. Thyroid cancer was diagnosed in six nodules (2.5%), and all six patients were disease free after median follow-up of 4.9 years. Malignancy was more common in nodules >4 cm (15.4%; P = 0.037) or that grew during follow-up (6.0%; P = 0.048). The likelihood of nodule growth (±SE) was 15% ± 3%, 24% ± 4%, and 49% ± 10% at 6, 12, and 24 months, respectively. Among nodules >2 cm, those with ≥25% cystic content grew more slowly than nodules <25% cystic; nodules <2 cm grew similarly regardless of cystic content., Conclusion: Benign cytology in pediatric thyroid nodules has a low false-negative rate similar to that in adults, and prognosis is excellent in the rare cases of malignancy. Resection of nodules >4 cm, combined with surveillance of smaller nodules and repeated aspiration for growth, detects most false-negative results. Follow-up ultrasound in 12 months is appropriate for most cytologically benign pediatric nodules, but delaying surveillance up to 24 months may be reasonable in large, predominantly cystic nodules.

Background: Tumor genotyping is transforming lung cancer care but requires adequate tumor tissue. Advances in minimally invasive biopsy techniques have increased access to difficult-to-access lesions, but often result in smaller samples. With the advent of highly sensitive DNA genotyping methods used for plasma analysis, we hypothesized that these same methods might allow genotyping of free DNA derived from fine needle aspiration supernatant (FNA-S)., Methods: We studied patients with known or suspected lung cancer undergoing fine needle aspirate (FNA). After spinning the sample for cellblock, the FNA-S (usually discarded) was saved for genotyping. Supernatant cell-free DNA (SN-cfDNA) was extracted and tested by both droplet digital PCR (EGFR, BRAF, KRAS mutations) and highly sensitive amplicon-based next-generation sequencing (NGS)., Results: 17 samples were studied, including 11 FNAs from patients with suspected lung cancer and 6 FNAs from patients with lung cancer and acquired drug resistance. Of 6 newly diagnosed adenocarcinomas, 4 had a driver mutations (1 EGFR, 2 KRAS, 1 HER2) found on tissue; all of these could be detected in SN-cfDNA. The EGFR driver mutation was detected in all 5 adenocarcinomas with acquired EGFR resistance and the EGFR T790 M in three cases, in agreement with cellblock., Conclusions: FNA-S is a rich source of fresh tumor DNA, potentially increasing the diagnostic yield from small FNAs. Through use of emerging techniques for highly sensitive genotyping, this widely available biospecimen has potential for facilitating rapid cancer genotyping at diagnosis and after drug resistance., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Pleural, pericardial, and peritoneal effusion specimens present diagnostic challenges and clinical opportunities for cytology. For the patient, these specimens may be the first diagnosis of malignancy or the first sign of disease recurrence. This review aims to provide useful approaches with which to resolve key difficulties in cytologic diagnosis through the use of ancillary studies, focusing on immunohistochemistry. These approaches are suggested in concert with clinical, radiographic, and morphologic findings. The differentiation of reactive mesothelial cells from malignant mesothelioma and adenocarcinoma is a recurring theme, and Wilms tumor 1 (WT1)/AE1/AE3, claudin 4, and BRCA1-associated protein 1 (BAP1) immunostains are useful new tools in the armamentarium. A targeted workup is suggested for patients with no known primary site or with multiple prior malignancies. Molecular and other biomarker testing can be performed on even modestly cellular fluid specimens and may allow patients to benefit from targeted therapy without the need for additional tissue biopsies. Cancer Cytopathol 2018;000:000-000. © 2018 American Cancer Society., (© 2018 American Cancer Society.)

Background: Diagnostic hemithyroidectomy (HT) is the most widely recommended surgical procedure for a nodule with indeterminate cytology; however, additional details may make initial total thyroidectomy (TT) preferable. We sought to identify patient-specific factors (PSFs) associated with initial TT in patients with indeterminate thyroid nodules., Methods: Retrospective analysis of all patients with a thyroid nodule ≥ 1 cm and initial cytology of atypia of undetermined significance or suspicious for follicular neoplasm between 2012 and 2015 who underwent thyroidectomy. Medical records were reviewed for patient demographics, neck symptoms, nodule size, cytology, molecular test results, final histopathology, and additional PSFs influencing surgical management. Variables were analyzed to determine associations with the use of initial TT. Logistic regression analyses were performed to identify independent associations., Results: Of 325 included patients, 182/325 (56.0%) had HT and 143/325 (44.0%) had TT. While patient age and sex, nodule size, and cytology result were not associated with initial treatment, five PSFs were associated with initial TT (p < 0.0001). These included contralateral nodules, hypothyroidism, fluorodeoxyglucose avidity on positron emission tomography scan, family history of thyroid cancer, and increased surgical risk. At least one PSF was present in 126/143 (88.1%) TT patients versus 47/182 (25.8%) HT patients (p < 0.0001). Multivariate logistic regression analysis demonstrated that these variables were the strongest independent predictor of TT (odds ratio 45.93, 95% confidence interval 18.80-112.23, p < 0.001)., Conclusions: When surgical management of an indeterminate cytology thyroid nodule was performed, several PSFs were associated with a preference by surgeons and patients for initial TT, which may be useful to consider in making decisions on initial operative extent.

Background: A thyroid nodule comprised almost exclusively of mature, benign-appearing squamous cells is an uncommon finding in fine-needle aspiration (FNA) biopsies of thyroid nodules. Reporting such specimens was not originally addressed by The Bethesda System for Reporting Thyroid Cytopathology. The authors correlated the biologic behavior of the specimens with their benign cytologic appearance through clinical, radiographic, and surgical follow-up., Methods: The pathology archives of 3 tertiary hospitals were searched for thyroid FNA specimens consisting of mature squamous cells without atypia. The authors reviewed all available slides and included only cases that were moderately to highly cellular; nucleated or anucleate squamous cells without atypia comprised the vast majority of the cellularity. Available clinical information and/or thyroid ultrasound examination(s) were reviewed by an endocrinologist or radiologist, respectively., Results: A total of 18 patients (7 men and 11 women; age range, 19-76 years) with 20 nodules met the prespecified inclusion criteria. The average nodule size was 2.1 cm. Common sonographic characteristics included a well-defined appearance, the lack of internal vascularity, a thin outer wall, general hypoechogenicity with low-intermediate internal echoes, and posterior acoustic enhancement. Clinical and radiographic follow-up (mean, 3.8 years; range, <1 to 9 years) was available for 9 patients, and all nodules were stable. All 4 cases with histologic follow-up were benign squamous-lined cysts., Conclusions: The findings of the current study suggest that thyroid FNA specimens comprised almost exclusively of mature squamous cells can be reported as benign. Cancer Cytopathol 2018;126:336-41. © 2018 American Cancer Society., (© 2018 American Cancer Society.)

Background: In older patients, thyroid nodules are frequently detected and referred for evaluation, though usually prove to be benign disease or low-risk cancer. Therefore, management should be guided not solely by malignancy risk, but also by the relative risks of any intervention. Unfortunately, few such data are available for patients ≥70 years old., Methods: All consecutive patients ≥70 years old assessed by ultrasound (US) and fine-needle aspiration (FNA) between 1995 and 2015 were analyzed. Clinical, US, and histologic data, including patient comorbidities and outcomes, were obtained. Imaging and cytology results from initial evaluation were reviewed to detect significant-risk thyroid cancer (SRTC), which was defined as anaplastic, medullary, or poorly differentiated carcinoma, or the presence of distant metastases. Overall survival analyses were then performed to assist with risk-to-benefit assessment., Results: A total of 1129 patients ≥70 years old with 2527 nodules ≥1 cm were evaluated. FNA was safe in all, and cytology proved benign in 67.3% of patients. However, FNA led to surgery in 208 patients, of whom 93 (44.7%) had benign histopathology. Among all patients who underwent FNA, only 17 (1.5%) SRTC were identified, all of which were preoperatively identifiable by imaging and/or cytology. These SRTC were responsible for all (n = 10; 0.9%) thyroid cancer deaths. Among all other patients (n = 1112), 160 deaths (14.4%) were confirmed during a median follow-up of four years. None of these were thyroid cancer related. Survival analysis for these 1112 patients demonstrated that a separate non-thyroidal malignancy or coronary artery disease at the time of nodule evaluation was associated with increased mortality compared to those without these diagnoses (hazard ratio = 2.32 [confidence interval 1.66-3.26]; p < 0.01), confirming these are important variables to identify prior to thyroid nodule evaluation., Conclusions: For patients ≥70 years old, US and FNA are safe and prove helpful in identifying SRTC and benign cytology. However, the surgical management of patients ≥70 years old presenting without high-risk findings should be tempered, especially when comorbid illness is identified.

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is an indolent thyroid tumor characterized by frequent RAS mutations and an absence of the BRAF V600E mutation commonly seen in classical papillary thyroid carcinoma (cPTC). The ability to differentiate potential NIFTP/follicular variant of papillary thyroid carcinoma (FVPTC) from cPTC at the time of fine-needle aspiration (FNA) can facilitate conservative management of NIFTP. The aim of the current study was to investigate how molecular testing may add to cytologic assessment in the pre-operative differentiation of potential NIFTP/FVPTC and cPTC. We had previously evaluated cytologists' ability to prospectively distinguish potential NIFTP/FVPTC from cPTC in a cohort of 56 consecutive FNAs diagnosed as malignant or suspicious for malignancy. We utilized this cohort to perform molecular analysis. Detected molecular abnormalities were stratified into two groups: (1) those supporting malignancy and (2) those supporting a diagnosis of potential NIFTP/FVPTC. The cytologists' characterization of cases and the detected molecular alterations were correlated with the final histologic diagnoses. Molecular testing was performed in 52 (93%) of the 56 cases. For the 37 cases cytologists favored to be cPTC, 31 (84%) had a molecular result that supported malignancy (28 BRAF V600E mutations, 2 NTRK1 fusions, 1 AGK-BRAF fusion). For the 8 cases that were favored to be NIFTP/FVPTC by cytologists, 7 (88%) had a molecular result that supported conservative management (1 NRAS mutation, 6 wild-type result). Seven cases were designated as cytomorphologically indeterminate for NIFTP/FVPTC or cPTC, of which 6 (86%) had a molecular result that would have aided in the pre-operative assessment of potential NIFTP/FVPTC or cPTC/malignancy. These included 3 BRAF V600E mutations in nodules that were cPTC on resection, an HRAS mutation, and a wild-type result in the 2 nodules that were NIFTP, and a TERT promoter mutation along with an NRAS mutation in a poorly differentiated thyroid carcinoma. For nodules with an FNA diagnosis of suspicious for malignancy or malignant, cytologists can differentiate most cases of potential NIFTP/FVPTC from cPTC. However, molecular testing may be valuable for a subset of cases, especially those that are indeterminate for potential NIFTP/FVPTC versus cPTC based on cytologic features alone.

Background: The characterization of poorly differentiated neoplasms in fine-needle aspiration (FNA) and small biopsy specimens usually requires immunohistochemistry (IHC) with a panel of markers. Because of an increasing need to preserve limited diagnostic material for tumor genotyping and a mounting demand for cost containment, the authors investigated the usefulness of dual-color IHC with antibodies directed against broad-spectrum keratins and SOX10, a neuroectodermal transcription factor consistently expressed in melanoma, in the workup of epithelioid malignant neoplasms., Methods: A total of 107 cases of FNA cell blocks (49 cases) and small biopsies (58 cases) were selected, including 34 melanomas, 31 epithelioid/pleomorphic sarcomas, and 42 carcinomas. IHC was performed on all specimens using a peroxidase-based brown chromogen for SOX10 and an alkaline phosphatase-based red chromogen for keratins AE1/AE3. The presence or absence of staining in lesional cells was scored., Results: The majority of tumors demonstrated 1 of 3 distinct patterns: 1) malignant melanomas with nuclear SOX10 (sensitivity of 94% and specificity of 95%); 2) epithelioid/pleomorphic sarcomas negative for both SOX10 and AE1/AE3 (sensitivity of 84% and specificity of 88%); and 3) carcinomas with cytoplasmic AE1/AE3 (sensitivity of 76% and specificity of 98%). In addition, a fourth pattern with cytoplasmic AE1/AE3 and nuclear SOX10 was observed in a subset of carcinomas, most notably triple-negative breast cancers., Conclusions: SOX10/keratin dual-color IHC appears to be an effective, sensitive, and specific test to distinguish between melanoma, sarcoma, and carcinoma. This approach can identify melanoma, prioritize additional studies, and limit the number of markers needed to workup an epithelioid malignant neoplasm, thereby potentially reducing costs and preserving valuable tissue for ancillary studies with which to guide therapy. Cancer Cytopathol 2018;126:179-89. © 2018 American Cancer Society., (© 2018 American Cancer Society.)

Ectopic intrathyroidal thymic tissue is a benign lesion of nonthyroid origin occasionally found in the pediatric thyroid gland. Accurate diagnosis of such lesions is critical to avoid unnecessary biopsy or surgery. Twelve children referred to our center for the concern of thyroid nodules were found to have intrathyroidal thymic tissue. Most of the lesions had a classic sonographic appearance of a hypoechoic mass with sharp margins and multiple focal internal nonshadowing echogenicities identical to thymic tissue. Sonography and, in select cases, fine-needle aspiration can be used to diagnose benign thymic tissue within the thyroid and avoid unnecessary surgery., (© 2017 by the American Institute of Ultrasound in Medicine.)

Background: The term "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) has replaced a subset of follicular variant of papillary thyroid carcinoma due to the indolent behavior of such tumors. NIFTPs are most often classified in an "indeterminate" diagnostic category. In the current study, the authors sought to identify cytologic features helpful in distinguishing NIFTP from other entities in these categories, particularly benign nodules., Methods: The authors retrospectively evaluated a consecutive cohort of 130 thyroid fine-needle aspiration (FNA) specimens with an indeterminate diagnosis and available histopathologic follow-up. All FNA specimens were evaluated using the ThinPrep method. Each FNA was blindly reviewed by 2 board-certified cytopathologists, who assessed overall cellularity; architectural parameters; and nuclear features, including nuclear pallor and fine chromatin, distinct nucleoli, and irregular nuclear membranes. Each case received a score of 0 to 3, based on the presence or absence of these 3 nuclear features., Results: Nuclear but not architectural features appeared to distinguish NIFTP from benign nodules. Ninety-one percent of the NIFTPs (32 of 35 NIFTPs) received a score of ≥2, compared with 35% of benign nodules (23 of 66 benign nodules) (P<.0001). In contrast, NIFTP could not be differentiated from the invasive/infiltrative follicular variant of papillary thyroid carcinoma using these criteria (P = 1.000). Nuclear scoring was found to be especially useful in atypia of undetermined significance/follicular lesion of undetermined significance (AUS); a score ≥2 enriched for NIFTP (39% vs 3% of AUS cases with a score <2), whereas a score <2 was more likely benign (85% vs 50% of AUS cases with a score ≥2)., Conclusions: In indeterminate FNA specimens, the distinction of a possible NIFTP from a benign thyroid nodule can be suggested using a simple nuclear scoring system that is most valuable in AUS aspirates. Cancer Cytopathol 2018;126:86-93. © 2017 American Cancer Society., (© 2017 American Cancer Society.)

Context: Thyroid nodule growth was once considered concerning for malignancy, but data showing that benign nodules grow questioned the use of this paradigm. To date, however, no studies have adequately evaluated whether growth rates differ in malignant vs. benign nodules., Objective: To sonographically evaluate growth rates in benign and malignant thyroid nodules ≥1 cm., Design: Prospective, cohort study of patients with tissue diagnosis of benign or malignant disease, with repeated ultrasound evaluation six or more months apart., Main Outcomes: Growth rate in largest dimension of malignant compared with benign thyroid nodules. Regression models were used to evaluate predictors of growth., Results: Malignant nodules (126) met inclusion criteria (≥6-month nonoperative followup) and were compared with 1363 benign nodules. Malignant nodules were not found to be uniquely selected or prospectively observed solely for low-risk phenotype. Median ultrasound intervals were similar (21.8 months for benign nodules; 20.9 months for malignant nodules). Malignant nodules were more likely to grow >2 mm/y compared with benign nodules [relative risk (RR) = 2.5, 95% confidence interval (CI), 1.6 to 3.1; P < 0.001], which remained true after adjustment for clinical factors. The RR of a nodule being malignant increased with faster growth rates. Malignant nodules growing >2 mm/y had greater odds of being more aggressive cancers [intermediate risk: odds ratio (OR) = 2.99; 95% CI, 1.20 to 7.47; P = 0.03; higher risk: OR = 8.69; 95% CI, 1.78 to 42.34; P = 0.02]., Conclusions: Malignant nodules, especially higher-risk phenotypes, grow faster than benign nodules. As growth >2 mm/y predicts malignant compared with benign disease, this clinical parameter can contribute to the assessment of thyroid cancer risk., (Copyright © 2017 Endocrine Society)

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) established a standardized, category-based reporting system for thyroid fine-needle aspiration (FNA) specimens. The 2017 revision reaffirms that every thyroid FNA report should begin with 1 of 6 diagnostic categories, the names of which remain unchanged since they were first introduced: (1) Nondiagnostic or Unsatisfactory; (2) Benign; (3) Atypia of Undetermined Significance (AUS) or Follicular Lesion of Undetermined Significance (FLUS); (4) Follicular Neoplasm or Suspicious for a Follicular Neoplasm; (5) Suspicious for Malignancy; and (6) Malignant. There is a choice of two different names for some of the categories: a laboratory should choose the one it prefers and use it exclusively for that category; synonymous terms (eg, AUS and FLUS) should not be used to denote 2 distinct interpretations. Each category has an implied cancer risk that ranges from 0% to 3% for the "Benign" category to virtually 100% for the "Malignant" category, and, in the 2017 revision, the malignancy risks have been updated based on new (post 2010) data. As a function of their risk associations, each category is linked to updated, evidence-based clinical management recommendations. The recent reclassification of some thyroid neoplasms as non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) has implications for the risk of malignancy, and this is accounted for with regard to diagnostic criteria and optional notes. Such notes can be useful in helping guide surgical management., (Copyright © 2017 American Society of Cytopathology. Published by Elsevier Inc. All rights reserved.)

Background: The reclassification of noninvasive follicular variant of papillary thyroid carcinoma as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) has created diagnostic and management issues for thyroid fine-needle aspiration (FNA). In response to these challenges, the authors' laboratory adopted a NIFTP policy including 1) stringent criteria (requiring pseudo-inclusions, papillae, and/or psammoma bodies) for a malignant diagnosis of papillary carcinoma to limit false-positive results due to NIFTP and 2) the use of explanatory notes in cases with cytomorphologic features suggestive of possible NIFTP to encourage lobectomy over thyroidectomy. This study examined the effects of this policy on FNA classification and subsequent surgical management., Methods: All thyroid FNAs performed at Brigham and Women's Hospital (n = 1300) during a 1-year period were evaluated for changes in the use of diagnostic categories, explanatory NIFTP notes, and surgical follow-up in comparison with historical controls., Results: The use of specific Bethesda categories did not significantly change. Only a single case of NIFTP was mistakenly classified as malignant. NIFTP was seldom suspected prospectively (17 of 1300; 1.3%); when NIFTP was suspected, cases were reported as suspicious for a follicular neoplasm/follicular neoplasm (n = 10) or suspicious for malignancy (SUS; n = 7). Five of the 7 SUS cases (71%) underwent partial thyroidectomy, compared to 19% of those classified as SUS without an explanatory NIFTP note (P < .02)., Conclusions: Thyroid FNA reporting modifications due to NIFTP affect only a small subset of specimens. When NIFTP is suspected, an explanatory note promotes limited surgical excision. More stringent criteria for malignancy affect few cases while potentially limiting false-positive diagnosis due to NIFTP. Cancer Cytopathol 2017;125:854-64. © 2017 American Cancer Society., (© 2017 American Cancer Society.)

Background: Next-generation sequencing (NGS) fails for many small biopsies (BXs) because of a low overall DNA concentration or tumor percentage. Cytology smears and liquid-based preparations (LBPs), or smears/LBPs, often contain abundant tumor cells and may provide adequate material for molecular testing when other materials are insufficient. This study examined the performance of smears/LBPs on a clinical NGS assay., Methods: This study retrospectively reviewed quality metrics from consecutive smear/LBP, core BX, and cell block (CB) cases run on a hybrid-capture NGS assay interrogating 309 cancer-related genes. The following quality metrics were compared: adequacy rate, initial DNA concentration, postshearing fragment size, post-library preparation fragment size, fragment size difference, insert size, total reads, passing-filter reads aligned, percent passing-filter unique reads aligned, mean target coverage, percentage of loci with >100× coverage, percent duplication rate, percent selected bases, and percent usable bases on bait., Results: Twenty-three of 26 smears/LBPs (88%) were successfully sequenced, whereas 77 of 87 core BXs (89%) and 29 of 30 CBs (97%) were. The mean target coverage, median insert size, and percent usable bases were significantly higher in the smear/LBP category. The postshearing fragment size and the percent duplication were significantly lower for smears/LBPs., Conclusions: The adequacy rate of cytology smears/LBPs for NGS is comparable to that of core BXs or CBs. Increased values for the mean insert size, mean target coverage, and percent usable bases, along with a lower duplication rate, suggest that smears/LBPs provide higher quality DNA than formalin-fixed material. Cytology smears/LBPs can serve as a valuable source of material for molecular testing. Cancer Cytopathol 2017;125:786-94. © 2017 American Cancer Society., (© 2017 American Cancer Society.)

Background: Although objective measures of cytotechnologist (CT) and cytopathologist (CP) performance exist, challenges remain. Two assumptions deserve examination: CPs' interpretations are correct, and CTs and CPs render interpretations independently of each other. This study presents a CT-CP interpretation comparison and provides insight into these assumptions., Methods: Every gynecologic cytology specimen examined by both a CT and a CP from December 2004 to March 2015 was extracted from the laboratory information system; glandular interpretations were excluded. Excel and SAS were used for CT-CP pair analysis. CT-CP pairs with fewer than 32 specimens (the lowest quartile) were excluded. For the remaining CT-CP pairs, 30 specimens or 10% of the specimens (whichever was higher) were randomly selected for comparison by a weighted κ statistic. κ values greater than 0.6 represented good agreement within CT-CP pairs., Results: This study evaluated 7116 of 53,241 gynecologic cytology specimens (13.4%) that received CT and CP interpretations. This resulted in 155 pair-specific κ values from 15 CTs and 16 CPs. In aggregate, the κ values had a mean of 0.64, a standard deviation of 0.14, a median of 0.65, and a range of 0.27 to 0.91. Nine CTs exhibited good agreement in the majority of their pair-specific κ values with CPs (high-concordance CTs; 88 pair-specific κ values). This allowed us to identify outlier CPs who did not demonstrate good agreement with high-concordance CTs (16 of 88 pair-specific κ values [18.2%])., Conclusions: Laboratories can use this κ to determine when CP levels of agreement with CTs depart from those of their peers. Adding this to established metrics can give a more nuanced impression of CP performance. Cancer Cytopathol 2017;125:576-80. © 2017 American Cancer Society., (© 2017 American Cancer Society.)

The term noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was recently proposed to replace noninvasive follicular variant of papillary thyroid carcinoma (FVPTC) both to promote more conservative management of these tumors and spare patients the psychological burden of a cancer diagnosis. This reclassification will lower the incidence of papillary thyroid carcinoma (PTC). In addition, it could result in an increase in the rates of unfavorable histologic prognosticators for PTC overall because NIFTPs had previously accounted for many of the PTCs without these features. Our aim was to evaluate the potential impact of the reclassification of NIFTP on the rates of extrathyroidal extension, lymphovascular invasion, and lymph node metastases in PTC. We identified all PTCs clinically over 1 cm diagnosed on surgical resection between August 2010 and August 2012. The histopathologic characteristics, including PTC subtype, tumor size, presence of extrathyroidal extension and lymphovascular invasion, and surgical margin and lymph node status were all recorded. Based on these parameters, cases were classified according to the American Thyroid Association (ATA) risk stratification system for structural disease recurrence. Tumor slides for cases initially diagnosed as FVPTC were reviewed to identify tumors that would now be classified as NIFTPs. Our cohort included 348 cases of PTC, of which 94 (27%) would now be classified as NIFTPs. After excluding NIFTPs from the PTC category, there were increased rates of extrathyroidal extension (26% up from 19%, p = 0.046), lymphovascular invasion (37% up from 27%, p = 0.0099), and lymph node metastases (26% up from 19%, p = 0.045) among the remaining PTCs. Based on these changes in histologic features, 10% fewer cases were defined as ATA low risk (62% down from 72%, p = 0.0081). Our results indicate that the downgrading of some carcinomas to NIFTP will increase the rates of higher risk histologic parameters in the remaining PTCs by statistically significant margins. Although the overall survival for PTC is very high and would likely not be changed significantly by the introduction of NIFTP, additional studies evaluating the impact of the NIFTP shift are warranted.

Background: Thyroid nodules with atypia of undetermined significance (AUS) on fine-needle aspiration (FNA) have a low risk of malignancy that appears to vary based on specific features described in the AUS diagnosis. The Afirma gene expression classifier (GEC) is a molecular test designed to improve preoperative risk stratification of thyroid nodules, but its performance for different patterns of AUS has not been defined. The objective of this study was to assess GEC results and clinical outcomes in AUS nodules with architectural atypia (AUS-A), cytologic atypia (AUS-C) or both (AUS-C/A)., Methods: This was a retrospective review of all thyroid nodules with AUS cytopathology that underwent GEC testing at the authors' institution over a period of >4 years., Results: In 227 nodules that had AUS cytology results and Afirma GEC testing, the rate of benign GEC results was higher in AUS-A nodules (70 of 107; 65%) than in AUS-C/A nodules (25 of 65; 38%; P = .0008), and AUS-C nodules exhibited an intermediate rate of benign results (27 of 55 nodules; 59%). The risk of cancer among patients who had GEC-suspicious nodules, 86% of whom underwent resection, was 19% (6 of 25) for AUS-A nodules compared with 57% (21 of 37) for AUS-C/A nodules (P = .003) and 45% (10 of 22) for AUS-C nodules (P = .07). In nodules that had an indeterminate repeat cytology result, no difference was observed in the rate of benign GEC results or in the malignancy rate compared with nodules that had a single cytology result., Conclusions: The performance characteristics of Afirma GEC testing vary, depending on qualifiers of cytologic atypia. Recognition of these differences may enable clinicians to provide improved counseling and treatment recommendations to patients. Cancer Cytopathol 2017;125:313-322. © 2017 American Cancer Society., (© 2017 The Authors. Cancer Cytopathology published by Wiley Periodicals, Inc. on behalf of American Cancer Society.)

Background: Molecular testing of thyroid nodules is increasingly being utilized to guide clinical management decisions. RAS mutations are the most frequent mutations detected in the context of an indeterminate fine-needle aspiration (FNA) diagnosis. The term "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) was recently introduced to promote conservative management of tumors previously classified as noninvasive follicular variant of papillary thyroid carcinoma (FVPTC). This change in terminology was based on the indolent clinical behavior of these tumors and their molecular profile, which includes frequent RAS mutations. The aim of this study was to determine the percentage of RAS-mutant "carcinomas" that would now be classified as NIFTPs., Methods: A search was performed for cases with known activating RAS mutations in a database of 199 thyroid carcinomas that underwent molecular characterization as part of Profile:Oncopanel between July 2013 and July 2015. Cases of FVPTC were re-reviewed to identify tumors that now would be categorized as NIFTP. Preceding FNA diagnoses were recorded, and cases with an indeterminate FNA result (defined as a diagnosis of atypia/follicular lesion of undetermined significance, suspicious for follicular neoplasm, or suspicious for malignancy) were identified., Results: A total of 27 RAS-mutant thyroid tumors were identified. Fifteen (56%) cases had an NRAS mutation, nine (33%) had an HRAS mutation, and three (11%) had a KRAS mutation. Twenty-four (89%) cases had a preceding FNA, 19 (79%) of which had an indeterminate FNA diagnosis. The surgical resection specimen demonstrated FVPTC in 20 (74%) cases, classical type PTC in two (7%), solid variant of PTC in one (4%), and follicular thyroid carcinoma in four (15%). Of the 20 FVPTCs, 16 (80%) would now be classified as NIFTP. NIFTPs accounted for 59% of RAS-mutant carcinomas overall and 63% of RAS-mutant carcinomas with a prior indeterminate FNA diagnosis., Conclusion: NIFTPs accounted for more than half of RAS-mutant "carcinomas" in this cohort. In cases where clinical and sonographic data support a low-risk phenotype, these results suggest that a lobectomy should be considered as the initial surgical approach for a nodule with an indeterminate FNA diagnosis and a RAS mutation.

Introduction: This study constitutes the first systematic comparison of molecular results between different cytology preparations in patients with lung adenocarcinoma undergoing testing for EGFR, KRAS, and BRAF mutations., Materials and Methods: 115 archival cytology preparations (direct smears, ThinPrep preparations [TP], and cell blocks [CB]) from lung adenocarcinomas with known EGFR, KRAS, or BRAF mutations were tested and compared with clinical testing results. Results were compared between preparations and analyzed in relation to tumor purity and tumor cell content., Results: 82 (77%) of 106 informative cases were concordant with clinical testing results. There was no significant difference in the concordance rate between CB, TP, air-dried smears, or alcohol-fixed smears (P = 0.3803), nor between preparations with <25%, 25% to 50%, or >50% tumor purity (P = 0.1147). Concordance rates were lower in preparations with ≤100 tumor cells (P = 0.0002)., Conclusions: Smears, TP, and CB are all valid substrates for molecular testing. Although tumor purity did not significantly affect results, low tumor content showed poorer performance. Recording tumor purity and content is recommended., (Copyright © 2016 American Society of Cytopathology. Published by Elsevier Inc. All rights reserved.)

Context: Mutations in the BRAF and RAS oncogenes are responsible for most well-differentiated thyroid cancer. Yet, our clinical understanding of how BRAF-positive and RAS-positive thyroid cancers differ is incomplete., Objective: We correlated clinical, radiographic, and pathological findings from patients with thyroid cancer harboring a BRAF or RAS mutation., Design: Prospective cohort study., Setting: Academic, tertiary care hospital., Patients: A total of 101 consecutive patients with well-differentiated thyroid cancer., Main Outcome Measure: We compared the clinical, sonographic, and pathological characteristics of patients with BRAF-positive cancer to those with RAS-positive cancer., Results: Of 101 patients harboring these mutations, 71 were BRAF-positive, whereas 30 were RAS-positive. Upon sonographic evaluation, RAS-positive nodules were significantly larger (P = .04), although BRAF-positive nodules were more likely to harbor concerning sonographic characteristics (hypoechogenicity [P < .001]; irregular margins [P = .04]). Cytologically, 70% of BRAF-positive nodules were classified positive for PTC, whereas 87% of RAS-positive nodules were indeterminate (P < .001). Histologically, 96% of RAS-positive PTC malignancies were follicular variants of PTC, whereas 70% of BRAF-positive malignancies were classical variants of PTC. BRAF-positive malignancies were more likely to demonstrate extrathyroidal extension (P = .003), lymphovascular invasion (P = .02), and lymph node metastasis (P < .001)., Conclusions: BRAF-positive malignant nodules most often demonstrate worrisome sonographic features and are frequently associated with positive or suspicious Bethesda cytology. In contrast, RAS-positive malignancy most often demonstrates indolent sonographic features and more commonly associates with lower risk, "indeterminate" cytology. Because BRAF and RAS mutations are the most common molecular perturbations associated with well-differentiated thyroid cancer, these findings may assist with improved preoperative risk assessment by suggesting the likely molecular profile of a thyroid cancer, even when postsurgical molecular analysis is unavailable.