Indeterminate Thyroid Cytology Research Articles

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

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. 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 3years 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. 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. MDROMs and PCRs evaluate concordance with reference ROMs and with one another and provide individual feedback, which potentially facilitates quality improvement.

Molecular-Derived Risk of Malignancy of Indeterminate Thyroid Cytology Diagnoses as a Quality Metric for Individual Cytopathologists

Molecular-Derived Risk of Malignancy of Indeterminate Thyroid Cytology Diagnoses as a Quality Metric for Individual Cytopathologists

Unraveling the significance of TSHR mutations in indeterminate thyroid cytology specimens

We investigated the clinical significance of thyroid-stimulating hormone receptor (TSHR) mutations detected in thyroid fine needle aspiration (FNA) specimens. The pathology archives at our institution were reviewed between 2018 and 2021 for indeterminate (Bethesda category III and IV) specimens with Thyroseq® analysis showing TSHR mutations. A total of 2184 cases diagnosed as atypia/follicular lesion of undetermined significance (AUS/FLUS), and 2625 diagnosed as follicular neoplasm/suspicious for follicular neoplasm (FN/SFN) were identified. A total of 1735 AUS/FLUS and 2339 SFN/FN underwent Thyroseq® analysis; 69 showed TSHR mutations (1.6%, 59 female, 10 male, average age: 55 years). Ten cases showed oncocytic features. Twelve patients underwent radionuclide scans within 1 year of FNA:11 were hyperfunctioning. Nodule size and TSH levels were weakly correlated. Twenty-two different TSHR mutations were identified (most common: M453T). A second mutation was found in five cases (EZH1 n = 2, and EIF1AX n = 3). The expression of sodium-iodide transporter (NIS) mRNA was in the range of 0.01%-62.43% out of all sequencing reads, and was elevated in 49 (71%) cases. Surgical pathology follow-up was available in five cases (all benign except one). On follow-up available for 38 cases (mean: 24 months; range: 7-47 months), 34 (89.5%) nodules remained stable and 3 (8%) increased in size. TSHR mutations in thyroid FNA samples classified as indeterminate are rare, generally benign, and commonly associated with autonomy on scan if performed.

Indeterminate thyroid cytology in an iodine-deficient population: Prevalence, operation rate, risk of malignancy anddiagnostic value of thyroid scintigraphy and 18F-FDG PET imaging parameters.

Patients with indeterminate thyroid cytology often have a diagnostic hemithyroidectomy. The role of molecular imaging, particularly fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET), is controversial, and demographic variations in tumor prevalence and histology influence test performance and clinical utility. We retrospectively assessed the prevalence of indeterminate thyroid cytology and the malignancy rate in patients from an iodine deficient area, and evaluated the diagnostic value of preoperative thyroid scintigraphy and 18F-FDG PET/CT among operated patients. From 2006-2018, all patients with indeterminate thyroid cytology from the North Denmark region were included in the study (population 600,000).Clinical data, including operation rate, preoperative molecular imaging, and histopathological diagnosis, were retrieved. The results from preoperative thyroid scintigraphy and 18F-FDG PET/CT-scanning were compared to the final histopathological diagnosis. Four hundred and thirty-three patients were found with indeterminate thyroid cytology.The main registered reasons for conducting a fine needle aspiration biopsy (FNAB) were "cold nodule", goiter or a palpable nodule (n=312). In 40 patients (9%), FNAB was registered as conducted due to a PET incidentaloma. Four hundred and two patients (93%) underwent diagnostic lobectomy, and this population formed the study population for the following explorative study: One-hundred and two patients (25%) had a malignant diagnosis. In 226 (56%) and 51 (25%) patients, respectively, preoperative thyroid scintigraphy and 18F-FDG PET/computed tomography (CT) was performed. Among patients with a final malignant disease who had a thyroid scintigraphy (40 patients), a cold nodule was seen in 90% of cases; one (atypical) patient presented a warm nodule. Among patients with a final malignant disease 16 patients (16%) had a 18F-FDG PET (incl. 3 missing PET scans). Among the 51 patients with preoperative 18F-FDG PET/CT, no difference in the PET-derived parameters was found between benign (n=33) and malignant tumors (n=13). The prevalence of malignancy (25%) was comparable with that in other studies. In patients with a preoperative thyroid scintigraphy, 90% of malignant cases had a cold nodule on scintigraphy. In patients with a preoperative PET/CT-scanning presenting focal 18F-FDG-uptake, PET-derived parameters had no diagnostic value. However, the diagnostic value of 18F-FDG-avidity vs. non-avidity needs to be addressed prospectively.

ODP474 Critical Analysis of the Thyroid Cytopathologic Diagnosis of Atypia of Undetermined Significance and Associated Clinical Outcomes

Abstract Introduction FNA is the optimal test for classifying concerning thyroid nodules. Approximately 15-30% of FNAs are indeterminate, representing diagnostic challenge with intra- and inter-observer variability among cytologists. The Bethesda System (BS) for cytopathology was created in 2007 to standardize thyroid cytology with corresponding malignancy risk. Our goal is to identify the incidence of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/ FLUS) and the percent of malignant AUS/FLUS cases at our institution. Methods Chart review of 3068 adult patients with FNA performed from 2003 to 2015 was completed, with attention to reports considered "indeterminant". BS for reporting thyroid cytology was not in use at our institution during that time. Cytopathology reports were evaluated for key descriptors concerning for AUS, FLUS, or follicular neoplasm. Results 461 cytology reports included language consistent with possible "indeterminate" cytology. These reports were reviewed with our institution's cytopathologist and retrospectively assigned an equivalent BS category. 241 cases were consistent with BS category III (7.86% of all thyroid nodule FNAs done during this time period). Molecular marker studies were not being performed at our institution on indeterminate thyroid cytology specimens during this time period. Of the patients who had indeterminate cytology consistent with BS category III, 66.3% (160/241) went for surgery. The malignancy rate was 27.5% (44/160) in the BS category III group. Conclusion Our data demonstrated that category III nodules in some practice settings may have a higher risk of malignancy than traditionally believed, and that guidelines recommending repeat FNA or observation merit reconsideration. Molecular marker testing on indeterminate thyroid cytology specimens has been shown to be helpful in determining cases for surgery and is now being utilized at our institution. Presentation: No date and time listed

Prospects of Testing Diurnal Profiles of Expressions of TSH-R and Circadian Clock Genes in Thyrocytes for Identification of Preoperative Biomarkers for Thyroid Carcinoma.

Thyroid Nodules (TN) are frequent but mostly benign, and postoperative rate of benign TN attains the values from 70% to 90%. Therefore, there is an urgent need for identification of reliable preoperative diagnosis markers for patients with indeterminate thyroid cytology. In this study, an earlier unexplored design of research on preoperative biomarkers for thyroid malignancies was proposed. Evaluation of reported results of studies addressing the links of thyroid cancer to the circadian clockwork dysfunctions and abnormal activities of Thyroid-Stimulating Hormone (TSH) and its receptor (TSH-R) suggested diagnostic significance of such links. However, there is still a gap in studies of interrelationships between diurnal profiles of expression of circadian clock genes and TSH-R in indeterminate thyroid tissue exposed to different concentrations of TSH. These interrelationships might be investigated in future in vitro experiments on benign and malignant thyrocytes cultivated under normal and challenged TSH levels. Their design requires simultaneous measurement of diurnal profiles of expression of both circadian clock genes and TSH-R. Experimental results might help to bridge previous studies of preoperative biomarkers for thyroid carcinoma exploring diagnostic value of diurnal profiles of serum TSH levels, expression of TSH-R, and expression of circadian clock genes.

Indeterminate thyroid cytology: detecting malignancy using analysis of nuclear images.

BackgroundThyroid nodules diagnosed as 'atypia of undetermined significance/follicular lesion of undetermined significance' (AUS/FLUS) or 'follicular neoplasm/suspected follicular neoplasm' (FN/SFN), according to Bethesda’s classification, represent a challenge in clinical practice. Computerized analysis of nuclear images (CANI) could be a useful tool for these cases. Our aim was to evaluate the ability of CANI to correctly classify AUS/FLUS and FN/SFN thyroid nodules for malignancy.MethodsWe studied 101 nodules cytologically classified as AUS/FLUS (n = 68) or FN/SFN (n = 33) from 97 thyroidectomy patients. Slides with cytological material were submitted for manual selection and analysis of the follicular cell nuclei for morphometric and texture parameters using ImageJ software. The histologically benign and malignant lesions were compared for such parameters which were then evaluated for the capacity to predict malignancy using the classification and regression trees gini model. The intraclass coefficient of correlation was used to evaluate method reproducibility.ResultsIn AUS/FLUS nodule analysis, the benign and malignant nodules differed for entropy (P < 0.05), while the FN/SFN nodules differed for fractal analysis, coefficient of variation (CV) of roughness, and CV-entropy (P < 0.05). Considering the AUS/FLUS and FN/SFN nodules separately, it correctly classified 90.0 and 100.0% malignant nodules, with a correct global classification of 94.1 and 97%, respectively. We observed that reproducibility was substantially or nearly complete (0.61–0.93) in 10 of the 12 nuclear parameters evaluated.ConclusionCANI demonstrated a high capacity for correctly classifying AUS/FLUS and FN/SFN thyroid nodules for malignancy. This could be a useful method to help increase diagnostic accuracy in the indeterminate thyroid cytology.

Afirma Testing in Thyroid Nodules with Indeterminate Cytology: A single Medical Institute Experience

Abstract Introduction/Objective About 10 to 30% of thyroid fine needle aspiration (FNA) nodules have indeterminate cytology, including Bethesda III, IV, and V. Afirma Gene Expression Classifier (GEC) measuring the expression of 167 mRNA was designed to classify the indeterminate thyroid nodules into benign and suspicious categories. This study aimed to evaluate the clinical performance of the Afirma GEC testing in these indeterminate thyroid lesions. Methods Medical records of patients with indeterminate thyroid FNA results and corresponding Afirma GEC results from November 2012 to December 2019 were retrieved. Subsequent surgical follow-up results were obtained. GEC results were compared to the histologic diagnoses. Results 1. There were 77 cases with indeterminate thyroid FNA results. Cytology diagnosis included 67 Bethesda III and 10 Bethesda IV. Afirma GEC results were benign for 41 cases (53%), suspicious for 32 cases (42%), and non- diagnostic for 4 cases (5%). Twenty seven of 32 cases (84%) with suspicious GEC results had surgical follow-up which revealed 12 malignant and 15 benign histologic diagnoses. Only 11 of 41 cases (27%) with benign GEC results had surgery which showed 8 benign and 3 malignant diagnoses. Based on the data, the sensitivity of this test is 80% and specificity is 65%. Positive predictive value (PPV) is 44% and negative predictive value (NPV) is 73%. The false positive cases include 5 Hurthle cell adenoma, 4 nodular hyperplasia, 3 follicular adenoma, 2 Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFPT), and 1 lymphocytic thyroiditis. The false negative cases include 2 minimally invasive follicular carcinoma (from same patient) and 1 papillary thyroid carcinoma. Conclusion 1. We demonstrated in this study that a little more than half of the cases with indeterminate thyroid cytology had negative Afirma GEC results. 2.Afirma test has relatively low specificity (65%) and PPV (44%). The sensitivity (80%) and NPV (73%) is relatively higher but is lower than the values in most literature. This could be due to the fact that majority of the Afirma GEC negative cases in this study did not have surgical follow-up and the sample size is small. 3.Afirma GEC test is a relatively good “rule-out” molecular test for indeterminate thyroid nodules but is not a reliable “rule-in” test due to the low specificity and PPV.

Impact of a genomic classifier on indeterminate thyroid nodules: an institutional experience

Indeterminate thyroid cytology (ITC) occurs in 20% to 25% of cases, and the associated risk of malignancy ranges from 5% to 30%. The genomic classifier ThyroSeq (CBLPath/UPMC, Rye Brook, NY), a targeted next-generation sequencing technology, could classify ITC nodules as malignant and nonmalignant. We sought to characterize our institutional experience with ThyroSeq testing. We retrospectively identified all patients seen from January 2015 through November 2019 who had ITC nodules analyzed with ThyroSeq. Relevant clinical, pathologic, and resection data were reviewed. Of the 133 cases identified, diagnostic categories included atypia (or follicular lesion) of undetermined significance) (n = 65 [48.9%]), suspicious for follicular neoplasm (SFN) (n = 48 [36.1%]), and suspicious for Hürthle cell neoplasm (n = 20 [15.0%]). About half of the papillary thyroid carcinoma (PTC) cases (n = 9 [56.3%]) and more than one-third of the noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) cases (n = 3/8 [37.5%]) were classified as SFN. Most patients (n = 87 [65.4%]) did not undergo resection; of these, 73 (83.9%) were negative for all molecular alterations. Of the 54 cases with molecular alterations, isolated RAS or RAS-like variants were most common (n = 35 [64.8%]); 9 (25.7%) were identified in PTC and 8 (22.9%) in NIFTP. NRAS was the most common alteration (n = 20 [37.0%]), followed by HRAS (n = 6 [11.1%]), which was mostly detected in NIFTP cases (n = 4 of 6 [66.7%]). Resection was avoided in 73 patients (54.9%) because of negative ThyroSeq results. ThyroSeq v2 and v3 offered a more accurate categorization of ITC nodules, improved patient management, and reduced unnecessary surgical procedures.

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

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. 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. 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. 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.

The pursuit of understanding multinucleated giant cells in indeterminate and malignant thyroid cytology samples.

Multinucleated giant cell (MGC) present in a variety of non-neoplastic and neoplastic lesions of the thyroid on cytology samples. We aimed to investigate whether certain MGC features that can help us in routine cytopathology practice. One hundred and thirty seven cases thyroid fine-needle aspiration material, which was diagnosed as indeterminate or malignant according to the Bethesda categorization, were reviewed. All cytomorphological features of the MGCs were documented. These features correlated with Bethesda categories and the final diagnosis of the subsequent surgical specimen. The presence of the MGCs was identified in 42% of the samples (58 cases-total 236 MGCs). Eighty eight of them (37%) had dense cytoplasm, 148 of them had foamy cytoplasm. The mean number of dense and foamy MGC per case was higher in the malignant category (3.2 for dense MGC and 6 for foamy MGC per case). All dense MGCs were found to be in patients with papillary thyroid carcinoma (PTC). Remarkably, follicular patterned lesions had less often dense MGC compared to papillary patterned lesions (16.6% and 46.8% respectively). We detected a nuclear irregularity in 49 dense MGC (55%), groove-like features in 24 dense MGC (27.2%), and presence of some material/cell in 8 dense MGC (9%). The presence of dense MGC is an important finding for guiding accurate Bethesda categorization, especially in indeterminate and malignant categories. Besides, the presence of some material or cell in MGCs cytoplasm can be an important indicator for the prognosis of the PTC cases.

Molecular testing in diagnosis of indeterminate thyroid cytology: Trends and drivers.

Fine needle aspiration (FNA), the cornerstone of diagnosis in thyroid swellings, fails to render a definitive diagnosis in about 20% to 30% of cases that are reported as indeterminate on cytology. Since the clinical management in thyroid rests on the risk of malignancy (ROM) in a given nodule, this distinction between "benign" and "possibly malignant" assumes paramount clinical importance. Over the last two decades, tremendous progress has been achieved in our understanding of the molecular basis of thyroid pathologies leading to identification of several genetic alterations that could potentially be exploited for diagnostic, prognostic and therapeutic purposes. An array of molecular tests has hit the markets aiming to predict the ROM in thyroid nodules. A deeper understanding of the strengths and limitations of these tests is imperative to be able to judiciously choose the right molecular test in a given case for maximum clinical benefit. This narrative review provides an overview of current status of molecular testing in the evaluation of thyroid nodules encompassing the current status and applications of these tests in diagnostic, prognostic and therapeutic areas along with a brief insight into the future developments in this field.

Abstract #804230: Slide-Based Molecular Testing Including Microrna. Salvage of Insufficient Aspirate Molecular Results in Nodules with Indeterminate Thyroid Cytology

Abstract #804230: Slide-Based Molecular Testing Including Microrna. Salvage of Insufficient Aspirate Molecular Results in Nodules with Indeterminate Thyroid Cytology

Molecular-derived estimation of risk of malignancy for indeterminate thyroid cytology diagnoses

One of the key features of the Bethesda System for Reporting Thyroid Cytopathology is the risk of malignancy (ROM), which guides management for each diagnostic category. However, calculation of the ROM can be challenging for indeterminate diagnoses because only a portion of cases will be resected for cytologic-histologic correlation (CHC) analyses. In the present study, we used the probability of cancer information from ThyroSeq, version 3, reports to calculate the molecular-derived (MD) ROM for indeterminate categories. Cytology cases with indeterminate BSRTC diagnoses and adequate molecular test results were retrieved from our cytopathology laboratory for a 12-month period. The probability of cancer information from the ThyroSeq, version 3, molecular reports were tabulated, and the mean ROM was calculated for each diagnostic category. The MDROM included noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) as a "malignant" outcome because it is considered a surgical disease. A total of 361 cases had adequate material for molecular testing. The diagnostic distribution was as follows: atypia of undetermined significance/follicular lesion of undetermined significance, 271 cases (75.1%), follicular neoplasm/suspicious for a follicular neoplasm, 59 cases (16.3%), and Hürthle cell type/suspicious for a follicular neoplasm, Hürthle cell type, 31 cases (8.6%). The corresponding estimated MDROMs were 14.9%, 32.6%, and 34.4%. A comparison with the CHC data was performed, and the 95% confidence intervals of the MDROMs overlapped well with the 2 endpoint CHC values. Calculation of the MDROMs provides a new method to approximate the ROMs of indeterminate diagnoses and has the advantage of potentially evaluating all cases, not just those resected. Furthermore, for those using the same platform, interinstitutional comparisons will be possible.

Testing for Afirma in Thyroid Nodules with High-Risk Indeterminate Cytology (TIR3B): First Italian Experience.

A percentage of 15 to 30% of thyroid fine-needle aspiration (FNA) is indeterminate, i.e., TIR3A and TIR3B according to the Italian consensus for thyroid cytology. Afirma, a molecular analysis of thyroid FNA specimens, has recently gained popularity as an adjunct to microscopic cytological evaluation, in order to avoid diagnostic surgery in patients with indeterminate thyroid cytology. We described the first Italian experience with Afirma tests in a single Italian institution and assessed the performance of the Afirma test in TIR3B. Moreover, this is a preliminary study to assess the patient response to the offer of Afirma testing. The Afirma test was proposed to 67 patients with thyroid nodules that had yielded TIR3B cytology. Fifty-one patients (76.1%) chose the Afirma test, 25/51 underwent the test but the remaining 26 did not because of cost. A total of 41/67 (61.2%) patients underwent surgery, and 22/41 (53.7%) nodules were carcinomas. Of the 25 tested by Afirma, 9 (36%) were classified as Afirma-suspicious (Afirma-S); seven of them underwent surgery, and in 6/7 (85.7%), a cancer was proven at histology. Afirma is the procedure that many Italian patients with TIR3B lesions would choose. However, its routine clinical application in Italy is currently limited by high costs for the patient. When Afirma is performed in this setting of patients, the cancer risk of suspicious result is higher than that expected in all the series of TIR3B. Therefore, testing for Afirma in these nodules may be useful for managing patients and tailoring their surgical approach.

Digital Gene Expression Analysis on Cytology Smears Can Rule Out Malignancy in Follicular-Patterned Thyroid Tumors

Patients with indeterminate thyroid nodules (Bethesda III and IV) are often treated with diagnostic lobectomy, which in most cases represents an overtreatment. A reliable rule-out molecular test could spare patients unnecessary surgery. Stained smears of 88 indeterminate thyroid nodules with histologic diagnosis of follicular-patterned tumors were selected: 34 follicular adenomas (FAs), 34 follicular variant papillary thyroid carcinomas (FVPTCs), and 20 noninvasive follicular neoplasms with papillary-like nuclear features (NIFTPs). The expression level of 126 genes was measured by digital counting. Mutation testing was performed for the main gene mutations and fusions. Performance of gene expression and mutation tests was calculated by receiver operating characteristic analysis. The gene expression model showed an area under the curve (AUC) of 88%, with 91% negative predictive value in FAs and FVPTCs only. Part of NIFTPs was labeled as benign, and part was labeled as malignant; thus, the classifier performance worsened. Two FAs (5.9%), eight NIFTPs (40%), and 22 FVPTCs (64.7%) were mutation positive. Mutation testing AUC was 79% in FAs and FVPTCs, and decreased by including NIFTPs. This gene expression-based test was feasible in thyroid-stained smears, showed higher AUC than mutation test, and had a high negative predictive value-making it a good candidate as a rule-out test for indeterminate thyroid cytology. NIFTPs have a heterogeneous phenotype, and their preoperative diagnosis requires further investigation.

Semiquantitative assessment of cytomorphologic features can predict mutation status of thyroid nodules with indeterminate cytologic diagnosis

Molecular diagnostics increasingly direct the management of thyroid nodules with an indeterminate cytologic diagnosis. This study was undertaken to correlate cytomorphologic features with the molecular profiles in an effort to identify features predictive of molecular aberrations. One hundred eighty-nine thyroid nodules with an indeterminate thyroid cytology diagnosis (atypia of undetermined significance, suspicious for follicular lesion, and suspicious for malignancy) with an adequate sample submitted for targeted mutation detection by polymerase chain reaction or next-generation sequencing were assessed semiquantitatively for the following cytomorphologic parameters: cellularity, Hurthle cell changes, microfollicles, nuclear elongation, nuclear grooves, nuclear enlargement, nuclear atypia, extent of atypia, and colloid. Based on this evaluation, a cumulative cytomorphologic score (CCS) and a more simplified overall atypia score (OAS) were assigned to each case. Associations among mutational status and each of the aforementioned parameters, CCS, and OAS were determined. Of the 189 nodules with indeterminate cytology, 63 (33.3%) harbored at least 1 mutation. RAS and BRAF were the most common mutations, found in 34 (18.0%) and 13 (6.9%) cases, respectively. Both CCS and OAS were highly associated with the presence of all mutations (P < .0001) and with the presence of BRAF and RAS mutations in particular (all P < .01). Semiquantitative assessment of various cytomorphologic features in indeterminate thyroid cytology cases showed a strong association of higher OAS and CCS and incidence of BRAF and RAS mutations. Using a more objective approach to thyroid cytology can potentially decrease the overall number of indeterminate diagnoses, leading to fewer repeat procedures and unnecessary surgical procedures.

Thyroid cytopathology: updates and molecular testing.

SummaryThe utility of fine needle aspiration (FNA) is well described in the context of evaluating thyroid lesions. Among the various international systems of classification of thyroid cytology, the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has also provided a sound framework to standardize the reporting of FNA cytology results. New molecular evidence and clinical studies demonstrated the need for revision of the nomenclature resulting in introduction of new categories, such as the noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP). Indeterminate thyroid cytology results pose a challenge for further management and the continued development of molecular markers may aid in the management of indeterminate thyroid lesions.

Indeterminate Thyroid Cytology and Impact of Noninvasive Follicular Thyroid Neoplasm with Papillary-like Features on Preoperative Diagnosis

Abstract Since the introduction of “noninvasive follicular thyroid neoplasm with papillary-like features” terminology, there has been much discussion and debate on how to best accommodate this new classification and its anticipated effect on cytologic preoperative risk of malignancy. Noninvasive follicular thyroid neoplasm with papillary-like features is a recently proposed terminology that was applied to a subset of noninvasive follicular variant of papillary thyroid carcinomas to avoid the label of “cancer.” In this review, the impact of noninvasive follicular thyroid neoplasm with papillary-like features on thyroid FNA diagnosis and risk of malignancy is discussed, as well as its impact on the 2017 updates to the Thyroid Bethesda system classification. Minimal cytologic criteria for establishing a definitive diagnosis of papillary thyroid carcinoma are discussed, as well as detailed diagnostic criteria of the indeterminate thyroid categories, which include atypia/follicular lesion of undetermined significance, follicular neoplasm/suspicious for follicular neoplasm, and suspicious for malignancy. The role of molecular testing in management is briefly visited.

Diagnostic utility of molecular and imaging biomarkers in cytological indeterminate thyroid nodules

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