Cancer Risk Associated with Nuclear Atypia in Cytologically Indeterminate Thyroid Nodules: A Systematic Review and Meta-Analysis

A Comprehensive Approach to the Thyroid Bethesda Category III (AUS) in the Transition Zone Between 2nd Edition and 3rd Edition of The Bethesda System for Reporting Thyroid Cytopathology: Subcategorization, Nuclear Scoring, and More

Significant interobserver variabilities exist for Bethesda category III: atypia of undetermined significance (AUS) of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Thus, subcategorization of AUS including AUS "nuclear" and AUS "other" is proposed in the recent 3rd edition of TBSRTC. This study investigated the impact of the nuclear features/architectural features/nuclear score (NS) (3-tiered)/subcategories and subgroups on risk of malignancy (ROM) in thyroid fine-needle aspirations (FNA). 6940 FNAs were evaluated. 1224 (17.6%) cases diagnosed as AUS were reviewed, and 240 patients (initial FNAs of 260 nodules and 240 thyroidectomies) were included. Subcategories and subgroups were defined according to TBSRTC 2nd and 3rd editions. Histological diagnostic groups included nonneoplastic disease, benign neoplasm, low-risk neoplasm, and malignant neoplasm. Overall, ROM was 30.7%. ROM was significantly higher in FNAs with nuclear overlapping (35.5%), nuclear molding (56.9%), irregular contours (42.1%), nuclear grooves (74.1%), chromatin clearing (49.4%), and chromatin margination (57.7%), and these features were independent significant predictors for malignancy. FNAs with NS3 had significantly higher ROM (64.2%). Three-dimensional groups were significantly more frequent in malignant neoplasms (35.7%). ROM was significantly higher in AUS-nuclear subcategory (48.2%) and in AUS-nuclear and architectural subcategory (38.3%). The highest ROM was detected in AUS-nuclear1 subgroup (65.2%). ROM was significantly higher in the group including AUS-nuclear and AUS-nuclear and architectural subcategories, namely "high-risk group" than the group including other subcategories, namely "low-risk group" (42.0%vs 13.9%). In conclusion, subcategorization may not be the end point, and nuclear scoring and evaluation of architectural patterns according to strict criteria may provide data for remodeling of TBSRTC categories.

Two-tier subclassification of the Bethesda category III (atypia of undetermined significance/follicular lesion of undetermined significance) in thyroid cytology

BACKGROUND

The Bethesda category III, AUS/FLUS, comprises a heterogeneous group of thyroid lesions with variable risk of malignancy (ROM). This study evaluates ROM in two subgroups of this category based on nuclear atypia and architectural atypia.

METHODS

Cases in Bethesda category III were reported based on nuclear atypia (AUS) and architectural atypia (FLUS). ROM was calculated by comparing the cytologic diagnosis to the follow-up histologic diagnosis.

RESULTS

Among the 610 Bethesda category III cases in this study, 306 (50.2%) and 304 (49.8%) cases were reported as AUS and FLUS, respectively. One hundred and eighty six of 306 AUS (60.8%) and 193 of 304 FLUS (63.5%) cases underwent surgical intervention. ROM of the cases in Bethesda category III was 12.8% if all cases were counted and 20.6% if only surgical cases were counted. When analyzing separately, ROM of AUS cases was 17.0% and 28.0% with all cases and surgical cases only, respectively. For FLUS cases, ROM was 8.6% and 13.5% with all cases and surgical cases only, respectively.

CONCLUSION

In Bethesda category III, ROM in the cases with nuclear atypia was significantly higher than the cases with architectural atypia. Sub-classifying the Bethesda Category III cases with nuclear atypia and architectural atypia, respectively may better stratify the ROM.

Prospective Validation of ThyroSPEC Molecular Testing of Indeterminate Thyroid Nodule Cytology Following Diagnostic Pathway Optimization

Background: Molecular testing for cytologically indeterminate thyroid nodules (ITNs) is often reported with incomplete data on clinical assessment and ultrasound malignancy risk (USMR) stratification. This study aimed to clinically validate the diagnostic accuracy of a novel molecular test, assess the incremental preoperative malignancy risk of other clinical factors, and measure the impacts of introducing molecular testing at the population level. Methods: Comprehensive clinical data were collected prospectively for the first 615 consecutive patients with ITNs in a centralized health care system following implementation of a reflexive molecular test. Clinical data include patient history, method of nodule discovery, clinical assessment, USMR, cytology, molecular testing, and surgery or follow-up along with surgeon notes on surgical decision-making. Accuracy of molecular testing and the impact of the introduction of molecular testing were calculated. A multivariable regression model was developed to identify which clinical factors have the most diagnostic significance for ITNs. Results: A locally developed, low-cost molecular test achieved a negative predictive value (NPV) of 76-91% [confidence interval, CI 66-95%] and a positive predictive value (PPV) of 46-65% [CI 37-75%] in ITNs using only residual material from standard liquid cytology fine-needle aspiration (FNA). Sensitivity was highest (80%; [CI 63-92%]) in the American Thyroid Association (ATA) intermediate-suspicion ultrasound category, and lowest (46%; [CI 19-75%]) in the ATA high-suspicion ultrasound category. Following implementation of molecular testing, diagnostic yield increased by 14% (p = 0.2442) and repeat FNAs decreased by 24% (p = 0.05). Mutation was the primary reason for surgery in 76% of resected, mutation-positive patients. High-risk mutations were associated with a 58% (p = 0.0001) shorter wait for surgery. Twenty-six percent of patients with a negative molecular test result underwent surgery. Multivariable regression highlighted molecular testing and USMR as significantly associated with malignancy. Conclusions: Molecular testing improves preoperative risk stratification but requires further stratification for intermediate-risk mutations. Incorporation of clinical factors (especially USMR) with molecular testing may increase the sensitivity for detection of malignancy. Introduction of molecular testing offers some clinical benefits even in a low resection rate setting, and directly influences surgical decision-making. This study illustrates the importance of the local diagnostic pathway in ensuring appropriate integrated use of molecular testing for best outcomes.

Clinico-cytopathological subcategorization in thyroid nodules of atypia of undetermined significance/follicular lesion of undetermined significance using the TIRADS and Bethesda classifications

Introduction

Bethesda category III - atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) is a heterogeneous class of the Bethesda system for thyroid nodules. In order to clarify the therapeutic road for clinicians, this category was subclassified based on the cytopathological features. In this study, we evaluated the risk of malignancy, surgical outcome, demographic characteristics, and correlation of ultrasound features with the final outcome in patients with thyroid nodules based on AUS/FLUS subclassification.

Method

After evaluating 867 thyroid nodules from three different centers, 70 (8.07%) were initially diagnosed as AUS/FLUS. The cytopathologists re-interpreted the FNA samples and subclassified them into five subcategories: architectural atypia, cytologic atypia, cytologic and architectural atypia, and Hürthle cell AUS/FLUS, and atypia, which was not specified. Based on the suspicious ultrasound features, an appropriate ACR TI-RADS score was allocated to each nodule. Finally, the malignancy rate, surgical outcomes, and ACR TI-RADS scores were evaluated among Bethesda category III nodules.

Results

Among the 70 evaluated nodules, 28 (40%) were subclassified as Hürthle cell AUS/FLUS, 22 (31.42%) as cytologic and architectural atypia, 8 (11.42%) as architectural atypia, 7 (10%) as cytologic atypia, and 5 (7.14%) as atypia which was not specified. The overall malignancy rate was 34.28%, and the architectural atypia and Hürthle cell nodules displayed lower malignancy compared to other groups (P-Value<0.05). Utilizing ACR TI-RADS scores showed no statistical significance between Bethesda III subcategorization and ACR TI-RADS scores. However, ACR TI-RADS can be a reliable predictor for Hürthle cell AUS/FLU nodules.

Conclusion

ACR TI-RADS helps evaluate malignancy only in the Hürthle cell AUS/FLUS subcategory of AUS/FLUS. Besides, cytopathological reporting based on the suggested AUS/FLUS subclassification could help clinicians take appropriate measures to manage thyroid nodules.

Application of machine learning methods to guide patient management by predicting the risk of malignancy of Bethesda III-V thyroid nodules

OBJECTIVE

Indeterminate thyroid nodules (ITN) are common and often lead to (sometimes unnecessary) diagnostic surgery. We aimed to evaluate the performance of two machine learning methods (ML), based on routinely available features to predict the risk of malignancy (RM) of ITN.

DESIGN

Multi-centric diagnostic retrospective cohort study conducted between 2010 and 2020.

METHODS

Adult patients who underwent surgery for at least one Bethesda III-V thyroid nodule (TN) with fully available medical records were included. Of the 7917 records reviewed, eligibility criteria were met in 1288 patients with 1335 TN. Patients were divided into training (940 TN) and validation cohort (395 TN). The diagnostic performance of a multivariate logistic regression model (LR) and its nomogram, and a random forest model (RF) in predicting the nature and RM of a TN were evaluated. All available clinical, biological, ultrasound, and cytological data of the patients were collected and used to construct the two algorithms.

RESULTS

There were 253 (19%), 693 (52%), and 389 (29%) TN classified as Bethesda III, IV, and V, respectively, with an overall RM of 35%. Both cohorts were well-balanced for baseline characteristics. Both models were validated on the validation cohort, with performances in terms of specificity, sensitivity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve of 90%, 57.3%, 73.4%, 81.4%, 84% (CI95%: 78.5%-89.5%) for the LR model, and 87.6%, 54.7%, 68.1%, 80%, 82.6% (CI95%: 77.4%-87.9%) for the RF model, respectively.

CONCLUSIONS

Our ML models performed well in predicting the nature of Bethesda III-V TN. In addition, our freely available online nomogram helped to refine the RM, identifying low-risk TN that may benefit from surveillance in up to a third of ITN, and thus may reduce the number of unnecessary surgeries.

PET/CT May Assist in Avoiding Pointless Thyroidectomy in Indeterminate Thyroid Nodules: A Narrative Review

Indeterminate thyroid nodules (ITN) are commonly encountered among the general population, with a malignancy rate of 10 to 40%. However, many patients may be overtreated with futile surgery for benign ITN. To avoid unnecessary surgery, PET/CT scan is a possible alternative to help differentiate between benign and malignant ITN. In this narrative review, the major results and limitations of the most recent studies on PET/CT efficacy (from PET/CT visual assessment to quantitative PET parameters and recent radiomic features analysis) and on cost-effectiveness (compared to other alternatives (such as surgery)) are presented. PET/CT can reduce futile surgery with visual assessment (around 40%; if ITN ≥ 10 mm). Moreover, PET/CT conventional parameters and radiomic features extracted from PET/CT imaging can be associated together in a predictive model to rule out malignancy in ITN, with a high NPV (96%) when certain criteria are met. Even though promising results were obtained in these recent PET/CT studies, further studies are needed to enable PET/CT to become the definitive diagnostic tool once a thyroid nodule is identified as indeterminate.

The influence of papillary features on the risk of malignancy in thyroid nodules diagnosed as atypia of undetermined significance or follicular lesion of undetermined significance

BACKGROUND

The objective of this study was to the assess the risk of malignancy in thyroid lesions that were diagnosed as AUS/FLUS when using a novel cytology subclassification system that is based on the presence or absence of papillary features.

METHODS

AUS/FLUS case cytology was re-reviewed and subclassified into minor or major concern groups based upon the absence or presence of papillary features, respectively. The risk of malignancy (ROM) was calculated and compared between the two groups. Inter-pathologist agreement in case subclassification was also measured.

RESULTS

The minor concern group had a 12.6% associated ROM, while the major concern group had a significantly higher ROM (58.4%), (P < 0.001). Based on 108 cases, the inter-pathologist agreement in case subclassification was 79%, and the κ value was 0.47.

CONCLUSIONS

The identification of papillary features significantly increases the ROM in thyroid lesions with an AUS/FLUS diagnosis.

Risk assessment of cytologically indeterminate thyroid nodules with integrated molecular testing and repeat biopsy: a surgical decision-oriented tool

BACKGROUND

The preoperative diagnosis of cytologically indeterminate thyroid nodules (ITNs) is very challenging. In this study, we aim to provide an integrated risk assessment for thyroid nodules with indeterminate cytology to guide surgical decision-making, which includes results of blood tests, molecular tests, and repeat fine-needle aspiration biopsy (FNAB).

METHODS

The study retrospectively included 265 ITNs between June 2019 and April 2022. According to our integrated risk assessment process that starts with blood testing, followed by supplementary DNA mutation detection on the first FNAB, and finally repeat FNAB, we divided the ITNs into high-risk and low-risk groups. Performance was evaluated with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), area under the receiver operating characteristic curve (AUC), and the consistency between the risk evaluation and histological results.

RESULTS

Of the 265 ITNs, 87 were included in the risk assessment process. The risk assessment had a sensitivity of 84.1%, specificity of 83.3%, PPV of 95.1%, NPV of 57.7%, and AUC of 0.837. The nodules with consistent results between the risk groups and histological outcomes, which included malignant cases in the high-risk group and benign cases in the low-risk group, accounted for 83.9% of all risk-assessed nodules.

CONCLUSIONS

These data suggest that the integrated risk assessment might provide proper information for surgical decision-making in patients with ITNs.

Clinical value of molecular markers as diagnostic and prognostic tools to guide treatment of thyroid cancer

OBJECTIVE

Advances in our understanding of the molecular biology of thyroid tumours is being rapidly translated into their clinical management. This review summarizes the current use of molecular testing in thyroid tumours, focusing on their usefulness as diagnostic and prognostic tools to guide treatment with consideration of present limitations.

DESIGN

Considerations about molecular testing applications for the diagnosis and treatment of thyroid tumours are divided into four sections/roles: (1) evaluating cytologically indeterminate thyroid nodules; (2) guiding extent of surgery in indeterminate thyroid nodules; (3) completing histological characterization of thyroid tumours and (4) identifying actionable mutations in advanced progressive thyroid cancers.

RESULTS

Genomic testing can improve the presurgical malignancy risk assessment in indeterminate thyroid nodules. However, a prior in-depth analysis of institutional quality and outcomes of sonographical, cytological and histological characterization of thyroid tumours is necessary. Presently, it remains uncertain whether knowing the molecular profile of a cytologically indeterminate thyroid nodule might be advantageous to modify the extent of initial surgery. Molecular characterization of thyroid tumours can be a valuable adjunct to morphological diagnosis in some challenging cases, such as in low-risk follicular cell-derived neoplasms, or rare tumours. Finally, as selective kinase inhibitors are available, molecular testing in locally advanced/metastatic progressive thyroid cancers should also be integrated into the institutional clinical management pathway to improve outcomes and limit toxicity.

CONCLUSIONS

Molecular testing needs to be implemented into the local evidence-based clinical management thyroid nodule/cancer pathways to improve its diagnostic and prognostic value and to optimize cost-effectiveness.

Thyroid Nodules with Indeterminate FNAC According to the Italian Classification System: Prevalence, Rate of Operation, and Impact on Risk of Malignancy. An Updated Systematic Review and Meta-analysis

A thyroid nodule classified as indeterminate on fine-needle aspiration cytology (FNAC), hereafter referred to as an indeterminate thyroid nodule (ITN), represents a clinical dilemma. The Italian Consensus for the Classification and Reporting of Thyroid Cytology (ICCRTC) divides ITNs into low- and high-risk categories (i.e., TIR3A and TIR3B, respectively) to better manage patients. This study aimed to achieve high-evidence estimates of the prevalence, rate of operation, and risk of malignancy of ITNs, including TIR3A and TIR3B ITNs. This systematic review was conducted according to MOOSE to retrieve all original studies citing ICCRTC. The last search was performed in February 2022. The risk of bias of the included studies was assessed. Separate proportion meta-analyses were performed with a random-effect model using OpenMeta[Analyst]. The online search processed 271 studies, and 33 were finally considered. First, the cancer prevalence among ITNs was 32.4%. Second, the cancer prevalence among TIR3As was 12.4%, with heterogeneity (I₂ 90%) explained by a linear correlation between sample size and cancer rate (p = 0.009). Third, the cancer prevalence among TIR3Bs was 44.4%, with heterogeneity (I₂ 75%) explained by the inverse correlation between sample size and cancer rate (p = 0.031). Fourth, the prevalence of ITNs, TIR3A, and TIR3B among FNACs was 29.6%, 12.6%, and 12.9%, respectively, with sample size and TIR3B prevalence being inversely correlated (p = 0.04). Fifth, the operation rates of ITNs, TIR3A, and TIR3B were 54.3%, 48.3%, and 75.2%, respectively, and the sample size and TIR3A operation rate were inversely correlated (p = 0.010). These data strongly support the division of ITNs into low- and high-risk subcategories. Importantly for clinical practice, the cancer rate among ITNs is significantly influenced by the study sample size.

Personalized Diagnosis in Differentiated Thyroid Cancers by Molecular and Functional Imaging Biomarkers: Present and Future

Personalized diagnosis can save unnecessary thyroid surgeries, in cases of indeterminate thyroid nodules, when clinicians tend to aggressively treat all these patients. Personalized diagnosis benefits from a combination of imagery and molecular biomarkers, as well as artificial intelligence algorithms, which are used more and more in our timeline. Functional imaging diagnosis such as SPECT, PET, or fused images (SPECT/CT, PET/CT, PET/MRI), is exploited at maximum in thyroid nodules, with a long history in the past and a bright future with many suitable radiotracers that could properly contribute to diagnosing malignancy in thyroid nodules. In this way, patients will be spared surgery complications, and apparently more expensive diagnostic workouts will financially compensate each patient and also the healthcare system. In this review we will summarize essential available diagnostic tools for malignant and benignant thyroid nodules, beginning with functional imaging, molecular analysis, and combinations of these two and other future strategies, including AI or NIS targeted gene therapy for thyroid carcinoma diagnosis and treatment as well.

Are the anatomical, clinical, and ultrasound characteristics of thyroid nodules with Bethesda III or IV cytology and ACR TI-RADS 3, 4, or 5 able to refine the indications for molecular diagnostic tests?

OBJECTIVE

To analyze the association of clinical, anatomical, and ultrasound (US) characteristics of malignancies in Bethesda III or IV (III-B or IV-B) thyroid nodules.

METHODS

The association between malignancies and the following variables were analyzed: III-B or IV-B, age < 55 years and ≥ 55 years, sex, family history of thyroid cancer, history of irradiation, nodule size, and ACR TI-RADS classification in 62 participants who underwent thyroidectomy.

RESULTS

Of the 62 participants, 87.1% (54/62) were women, 74.2% were < 55 years old, 95.2% had no family history of thyroid cancer, 56.5% had nodules < 2 cm in size, 62.9% were IV-B, and 69.4% were ACR TI-RADS 4. Thirty-two patients had thyroid carcinoma, and 30 had benign histology. Among all factors associated with malignancy, only ACR TI-RADS 5 classification on US was found to be statistically significant (p = 0.014), while III-B with architectural atypia cytological classification was the only one significantly associated with benign status (p = 0.004).

CONCLUSION

Only a high risk of malignancy as assessed using US was able to refine the indication for molecular tests in a group of patients with indeterminate nodules. We found 85% (53/62) of III-B or IV-B thyroid nodules would benefit from available molecular diagnostic tests.

Indeterminate thyroid cytology: detecting malignancy using analysis of nuclear images

BACKGROUND

Thyroid 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.

METHODS

We 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.

RESULTS

In 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.

CONCLUSION

CANI 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.

TIRADS, SRE and SWE in INDETERMINATE thyroid nodule characterization: Which has better diagnostic performance?

Purpose

To assess Strain Ratio (SRE) and Shear Wave Elastography (SWE) accuracy alone and with TIRADS classification, for the risk stratification of indeterminate thyroid nodules.

Materials and methods

128 Patients with 128 indeterminate nodules candidates for thyroidectomy underwent preoperative staging neck ultrasound and were classified according to K-TIRADS score. After TIRADS evaluation, semi-quantitative (SRE) and quantitative (SWE expressed in kPa) elastosonography were performed and relative diagnostic performances, alone and in combination, were compared through ROC curves analysis. In order to maximize the SRE and SWE sensitivity and specificity, their cut-off values were calculated using the Liu test. Bonferroni test was used to evaluate statistically significant differences with a p value < 0.05.

Results

Sensitivity, specificity, PPV and NPV were, respectively, 71.4%, 82.4%, 62.5%, 87.5% for K-TIRADS baseline US, 85.7%, 94.1%, 85.7%, 94.1% for SRE and 57.1%, 79.4%, 53.3%, 81.8% for SWE (kPa expressed). SRE evaluation showed the best diagnostic accuracy compared to the SWE (kPa expressed) (p < 0.05) and to the K-TIRADS (p > 0.05). The association of SRE with conventional ultrasound with K-TIRADS score increased sensitivity (92.9% vs 71.4%) but decreased the specificity than conventional US alone (76.5% vs 82.4%).

Conclusion

Strain Elastosonography can be associated with K-TIRADS US examination in the thyroid nodule characterization with indeterminate cytology; in fact, adding the SRE to K-TIRADS assessment significantly increases its sensitivity and negative predictive value. However, further multicenter studies on larger population are warranted.

Combining the American Thyroid Association's Ultrasound Classification with Cytological Subcategorization Improves the Assessment of Malignancy Risk in Indeterminate Thyroid Nodules

Background: The risk of malignancy (RoM) of indeterminate thyroid nodules (ITNs) shows a high variability in interinstitutional cohorts. The RoM is partially associated with the cytological degree of atypia and the ultrasound (US) pattern. This study evaluated the cancer risk of ITNs by jointly considering the cytological subcategory and the American Thyroid Association (ATA)-based US risk classification. Methods: This study features a retrospective cohort from two Brazilian centers comprising 238 ITNs with confirmed outcomes. US classification, according to ATA-based guidelines, and cytological subcategorization were determined. The cytological subgroups were as follows: (1) nuclear atypia (NA) related to papillary thyroid carcinoma (PTC) but insufficient to categorize the cytology as suspicious for malignancy; (2) architectural atypia without NA (AA); (3) both architectural and nuclear atypia (ANA); (4) oncocytic pattern (OP) without NA; and (5) NA not related to PTC (NANP). NA was divided into three subgroups: nuclear size and shape, nuclear membrane appearance, and/or chromatin aspects. Results: The overall frequency of malignancy was 39.5%. Among the cytological subcategories, the highest RoM was related to the NA (43.9%) and to the ANA (43.5%), followed by AA (29.4%), and OP (9.4%). NA was positively and independently associated with cancer (odds ratio [OR]: 4.5; confidence interval [CI: 1.2-16.6]) as was the occurrence of ANA (OR 6.6 [CI 1.5-29.5]). AA and OP were not independently associated with cancer. Both ATA-based high- and intermediate-risk categories showed an independent association with cancer (OR 6.8 [CI 2.9-15.5] and OR: 2.6 [CI 1.1-5.8], respectively). ITNs with cytological findings of NA or ANA when combined with intermediate US patterns had RoM values of 47.5% and 56.7%, respectively. Both cytological subcategories, when combined with the ATA high-suspicion class reached an RoM >70%. The type of NA with the highest odds for cancer was related to the nuclear membrane (OR 11.5). Conclusions: The RoM of ITNs can reach almost 80% when both NA and ATA-based high-risk US features are present. The presence of such cytological features also increased the RoM in the ATA-based intermediate-risk US category. In addition, AA and OP were not independently related to higher cancer risk. These results strengthen the recommendations for combing cytological subcategorization and US risk classification in the workup for ITNs before the decision of a molecular testing, clinical observation, or diagnostic surgery.

Follicular Lesions with Papillary Nuclear Characteristics: Differences in Chromatin Detected by Computerized Image Analysis

Objective

Follicular lesions of the thyroid with papillary carcinoma nuclear characteristics are classified as infiltrative follicular variant of papillary thyroid carcinoma-FVPTC (IFVPTC), encapsulated/well demarcated FVPTC with tumour capsular invasion (IEFVPTC), and the newly described category "non-invasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) formerly known as non-invasive encapsulated FVPTC. This study evaluated whether computerized image analysis can detect nuclear differences between these three tumour subtypes.

Methods

Slides with histological material from 15 cases of NIFTP and 33 cases of FVPTC subtypes (22 IEFVPTC, and 11 IFVPTC) were analyzed using the Image J image processing program. Tumour cells were compared for both nuclear morphometry and chromatin textural characteristics.

Results

Nuclei from NIFTP and IFVPTC tumours differed in terms of chromatin textural features (grey intensity): mean (92.37 ± 21.01 vs 72.99 ± 14.73, p = 0.02), median (84.93 ± 21.17 vs 65.18 ± 17.08, p = 0.02), standard deviation (47.77 ± 9.55 vs 39.39 ± 7.18; p = 0.02), and coefficient of variation of standard deviation (19.96 ± 4.01 vs 24.75 ± 3.31; p = 0.003). No differences were found in relation to IEFVPTC.

Conclusion

Computerized image analysis revealed differences in nuclear texture between NIFTP and IFVPTC, but not for IEFVPTC.

The Correlation of Age with Prognosis of Atypia of Undetermined Significance and Follicular Lesion of Undetermined Significance in Thyroid Nodules

Purpose

Although some prognostic variables and risk factors for thyroid cancer (TC) are age-related, the association between age and the risk of TC in patients with thyroid nodules (TNs) assigned to atypia of undetermined significance (AUS) and follicular lesion of undetermined significance (FLUS) is poorly estimated. The aim of this study was to assess the histopathology of AUS/FLUS and the risk of TC according to the age of the patients at the time of AUS/FLUS diagnosis.

Patients and Methods

Among 5021 individuals treated for TNs at one institution from 2008 to 2018, 161 (3.2%) patients with 161 TNs assigned to the AUS/FLUS category (1 nodule per patient) were selected and stratified by age at initial diagnosis: <55 years, 55–75 years and >75 years. Logistic regression analysis was used to estimate the association of age with the risk of TC diagnosis.

Results

Ninety-one (56.52%) patients <55 years old, 58 (36.02%) patients 55–75 years old, and 12 (7.45%) individuals >75 years old were identified. There were 130 (80.7%) females and 31 (19.3%) males with a mean age of 50.6 ± 16.12 years. Among the evaluated TNs, 142 (88.2%) were ultimately diagnosed as benign, and 19 (11.8%) were diagnosed as malignant. Younger age in patients was significantly related to malignancy outcome (p=0.024 for age <55 years). Patients aged 55–75 years had a significantly lower risk of TC than the other age categories (p=0.040). The risks of high vascularity and fast tumor growth were significantly higher in the youngest category than in the other categories (age <55 years old: p=0.045 and p=0.002, respectively).

Conclusion

Although patients with TNs classified as AUS/FLUS by ultrasound-guided fine needle aspiration biopsy (UG-FNAB) are not typically qualified for surgery, it is worth noting that younger patients with an AUS/FLUS diagnosis might be at a higher risk of TC.

Is Subdivision of Atypia of Undetermined Significance AUS/Follicular Lesion of Undetermined Significance Cases According to Detailed Nuclear Features Vital for Assessing the Risk of Malignancy?

Background:

It has been known that the “atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS)” category is the most problematic category in Bethesda system due to its highly heterogeneous morphological features. Recently, it has been reported that aspirates including nuclear atypia in the AUS/FLUS category have a higher risk of malignancy.

Aims:

This study aimed to assess each nuclear property in aspirates with cytological atypia and also to determine the relationship with the risk of malignancy.

Material and Methods:

We reviewed 980 AUS/FLUS fine-needle aspirations (FNAs) performed between '2012 and 2019' at a single institution. We classified these aspirates into four groups: AUS-N (nuclear atypia), AUS-A (architectural atypia), AUS-H (Hurthle cell change), and AUS-O (other). Nuclear features were detailed sub-classified; size and shape (enlargement, elongation, and overlapping), membrane irregularities (irregular contours, grooves, pseudoinclusion), and chromatin characteristics (pale chromatin). The estimated risk of malignancy (ROM) was calculated for each subgroup.

Results:

Of 980 AUS/FLUS cases, follow-up histological outcome data were available for 209 cases. Among these cases, the estimated ROM was 27.8%. The ROM were 26.4%, 15.4%, and 22.5% for AUS-N, A, and H, respectively. The most common nuclear findings associated with ROM were nuclear groove (67.9%); irregular contours (76.9%) suspected pseudoinclusion (100%) and overlapping (56%) (P < 0,001). But nuclear findings such as nuclear enlargement, mild pleomorphism, or pale chromatin have a similar ROM as architectural atypia.

Conclusion:

Although it is known that the presence of cytological atypia in an AUS/FLUS nodule increases the estimated risk of malignancy, all nuclear properties are not equally effective in predicting malignancy risk. Emphasizing nuclear atypia details in reports of AUS case may be a more sensitive way to identify nodules with a high risk of malignancy.

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.

Thyroid nodules: diagnostic evaluation based on thyroid cancer risk assessment

Thyroid nodules are extremely common and can be detected by sensitive imaging in more than 60% of the general population. They are often identified in patients without symptoms who are undergoing evaluation for other medical complaints. Indiscriminate evaluation of thyroid nodules with thyroid biopsy could cause a harmful epidemic of diagnoses of thyroid cancer, but inadequate selection of thyroid nodules for biopsy can lead to missed diagnoses of clinically relevant thyroid cancer. Recent clinical guidelines advocate a more conservative approach in the evaluation of thyroid nodules based on risk assessment for thyroid cancer, as determined by clinical and ultrasound features to guide the need for biopsy. Moreover, newer evidence suggests that for patients with indeterminate thyroid biopsy results, a combined assessment including the initial ultrasound risk stratification or other ancillary testing (molecular markers, second opinion on thyroid cytology) can further clarify the risk of thyroid cancer and the management strategies. This review summarizes the clinical importance of adequate evaluation of thyroid nodules, focuses on the clinical evidence for diagnostic tests that can clarify the risk of thyroid cancer, and highlights the importance of considering the patient's values and preferences when deciding on management strategies in the setting of uncertainty about the risk of thyroid cancer.

Preoperative prediction of non-invasive follicular thyroid neoplasm with papillary-like nuclear features: a Canadian single-Centre experience

Background

An international group of experts recommended reclassifying non-invasive follicular variant of papillary thyroid cancers (FVPTC) as ‘non-invasive follicular thyroid neoplasm with papillary-like nuclear features’ (NIFTP) in April 2016. The purpose of this study was to establish preoperative clinical, laboratory, ultrasonographic, and cytological variables, which can differentiate NIFTP from FVPTC.

Methods

We conducted a retrospective chart review of consecutive patients from a single institution evaluated between January 2012 and December 2017. 203 adult patients underwent lobectomy or total thyroidectomy for a FVPTC during that period. Each patient’s medical chart was reviewed and information on pre-operative variables was recorded. An expert pathologist reviewed all surgical specimens and reclassified a subset of FVPTC as NIFTP according to the specific criteria.

Results

Overall, 44 patients were included in the NIFTP group and 159 in the non-NIFTP group. Mean age was 50.1 years in the NIFTP group and 50.7 in the non-NIFTP group. Most patients were female (86.4% (38/44) in the NIFTP group vs 79.8% (127/159) in the non-NIFTP group). More patients underwent lobectomy in the NIFTP group (50% (22/44) vs 16.4% (26/159) in the non-NIFTP group, p = < 0.0001). Less patients received radioactive iodine in the NIFTP group (31.8% (14/44) vs 52.2% (83/159) in the non-NIFTP group, p = 0.0177). Preoperative thyroglobulin levels were lower in NIFTP patients (Median 25.55 mcg/L +/− 67.8 vs 76.06 mcg/L +/− 119.8 in Non-NIFTP, p = 0.0104). NIFTP nodules were smaller (Mean size 22.97 mm +/− 12.3 vs 25.88 mm +/− 11.2 for non-NIFTP, p = 0.0448) and more often solid than non-NIFTP (93.2% (41/44) vs 74.8% (119/159) for non-NIFTP, p = 0.0067). 2017 ACR TIRADS nodule category of 1–4 on ultrasound had a negative predictive value and a sensitivity of 100% for NIFTP. ROC Curve Analysis demonstrated that a preoperative thyroglobulin level of 31.3 mcg/L had a sensitivity of 75% and a specificity of 62.5% to differentiate NIFTP from non-NIFTP cancers.

Conclusion

Lower preoperative thyroglobulin levels, smaller nodule size, solid texture and 2017 ACR TIRADS Category of 1–4 are more strongly associated with NIFTP than FVPTC and can favour less invasive surgical options such as lobectomy.

Prognosis of patients with differentiated thyroid carcinomas having a preoperative cytological report of indeterminate at low or high risk. A multicenter study

BACKGROUND

Italian cytology system for thyroid fine-needle aspiration (FNA) includes indeterminate lesions at low- (Tir 3A) and high-risk (Tir 3B). The present retrospective multicenter study was undertaken to compare the histological type of cancers and disease-free survival in these two groups.

METHODS

Eight institutions participated. Thyroid cancer patients diagnosed and followed-up after Tir 3A or Tir 3B were reviewed. Histological diagnosis was adopted as the gold standard. Patients were defined with cancer recurrence or no evidence of disease. Disease-free survival (DFS) was calculated. A non-parametric statistical analysis was used. DFS was estimated by Kaplan-Meier method and Hazard Ratio (HR) defined the slope of curves.

RESULTS

Two hundred and nine patients (median DFS 24 months) were enrolled and a 6.3% of these recurred. Tir 3B group had higher age (p = 0.014), larger cancer size (p = 0.0002), shorter DFS (p = 0.003), higher number of aggressive cancers (p = 0.006), and relapse frequency double than Tir 3A. At survival curves analysis, Tir 3B group had HR of 2.37 with respect to Tir 3A. At Cox's proportional hazard regression analysis histology was the only significant predictor of relapse.

CONCLUSIONS

While patients with thyroid FNA of Tir 3B should be addressed to surgery due to high likelihood of more aggressive cancer, a diagnostic surgery could be avoided in patients with Tir 3A if concurrent unsuspicious clinical features are found.

Combination of contrast-enhanced ultrasound and strain elastography to assess cytologically non-diagnostic thyroid nodules

The aim of the present study was to investigate the benefits of combining contrast-enhanced ultrasound (CEUS) and strain elastography (SE) for the diagnosis of thyroid nodules with non-diagnostic fine-needle aspiration cytology (FNAC) results. Between October 2013 and March 2017, CEUS and SE were performed in 226 patients (236 thyroid nodules) with non-diagnostic FNAC results prior to thyroidectomy. The diagnostic value of CEUS, SE and their combination (CEUS+SE) in distinguishing malignant from benign thyroid nodules was evaluated, using surgical pathology as a reference. Receiver operating characteristic curve analysis was used to assess the diagnostic performance of CEUS, SE and CEUS+SE in determining malignant thyroid nodules. Subsequently, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of CEUS, SE and CEUS + SE were calculated. The malignancy rate in patients with thyroid nodules and non-diagnostic FNAC results was 26.3% in the present study. The sensitivity, specificity, PPV, NPV, accuracy and area under the curve in predicting malignant thyroid nodules were 80.6, 85.6, 66.7, 92.5, 84.3 and 0.831%, respectively, using SE alone; 59.7, 95.9, 84.1, 86.9, 86.4 and 0.778%, respectively, using CEUS alone; and 83.9, 89.1, 73.6, 94.5, 88.1 and 0.865%, respectively, using the combination of CEUS and SE. Overall, the combination of CEUS with SE resulted in higher sensitivity, NPV and accuracy in the diagnosis of cytologically non-diagnostic thyroid nodules compared with CEUS or SE alone.

Evaluation of thyroid nodules classified as Bethesda category III on cytology and their malignancy rate: An institutional experience

Background:

Thyroid gland nodules are common and fine-needle aspiration (FNA) is the gold standard for screening those nodules. The Bethesda system for reporting thyroid cytolopathology standardized reporting thyroid nodules aspirations, but atypia of undetermined significance or follicular lesion of undetermined significance (Bethesda category III) was the most controversial category. The aim of our study is to review our institutional experience and analyze the clinical implications of making a diagnosis of AUS/FLUS (Bethesda category III).

Methods:

This is a retrospective study of an 889 thyroid FNAs from 825 patients in Salmaniya Medical Complex, during (January 2013–December 2017).

Results:

The most common cause for designating cases as AUS/FLUS (Bethesda category III) was the presence of features suggestive of papillary thyroid carcinoma, but not quite fulfilling the criteria for such diagnosis. Ninety-six cases were diagnosed as AUS/FLUS (10.7%), in which 26 (27%) patients underwent surgery without repeating the FNA, 25 (26%) underwent a second FNA and 43 (44.7%) patients were followed up by ultrasound. On repeating the FNA, 1 (4%) was unsatisfactory, 13 (52%) were benign, 10 (40%) were AUS/FLUS, and only 1 (4%) was categorized as malignant. Thirty cases were surgically excised, in which 4 (13.3%) were diagnosed as follicular adenoma, 2 (6.6%) as Hurthle cell adenoma, 9 (30%) as multinodular goiter, 5 (16.6%) as multinodular goiter with Hashimoto thyroiditis, 1 (3.3%) as colloid nodule with Hashimoto thyroiditis, and 9 (30%) as papillary thyroid carcinoma. Among all the cases diagnosed initially as AUS/FLUS (Bethesda category III), 9 (9.3%) cases were diagnosed as papillary thyroid carcinoma.

Conclusion:

Diagnostically, we almost meet the international standards of designating cases with AUS/FLUS (Bethesda category III) and approximate the risk of malignancy. However, the clinical management's guidelines should be followed to decrease the risk of unnecessary surgeries and their complications. There is a statistically significant correlation between the age and gender with the final histopathology report, respectively.

Subcategorisation of AUS/FLUS thyroid lesions as per the 2017 Bethesda System for Reporting Thyroid Cytopathology: a retrospective study from a tertiary care centre analysing risk of malignancy (ROM) of the different subcategories

Aims

The 2017 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) recommends subclassification of atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS) into six subcategories. The present study evaluates the risk of malignancy (ROM) and risk of neoplasm (RON) among these.

Methods

All thyroid aspirates reported as AUS/FLUS over a 4.5-year period, with available histology, were reviewed and subclassified as per TBSRTC. ROM and RON were calculated and compared.

Results

Of 2554 thyroid aspirates, 281 (11.0%) were AUS/FLUS. Eighty-one with available histology were evaluated. ROM was 51.8%. Cytologic and architectural atypia (AUS-C&A) was the most prevalent (62.9%), followed by Hürthle cell type (19.6%), AUS-A (11.1%), AUS-not otherwise specified (NOS) (7.4%), cytologic atypia (AUS-C) (4.9%) and atypical lymphoid cells (1.2%). Papillary thyroid carcinoma (PTC) and adenomatous goitre (AG) were the most common histological diagnoses (27% each). On histology, AUS-C had 2/4 PTC and 2/4 AG on histology. AUS-A had 4/9 follicular neoplasm (FN) and 2/9 non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) while AUS C&A had 18/51 PTC, 13/51 AG, 11/51 NIFTP and 5/51 FN. ROM and RON were similar across subcategories, ROM was the highest for AUS-C&A (58.8%), AUS-C (50%) and AUS-NOS (50%). NIFTP reclassification as non-malignant reduced ROM to 35.8% (absolute reduction of 16% and a relative decrease of 31%) with the greatest relative decrease seen in AUS-A (50%), followed by AUS-C&A (37%), and none in others.

Conclusions

AUS/FLUS subcategorisation helped to indicate risk for the more likely neoplasm, whether PTC or FN. ROM was the highest for cases with cytological atypia but did not differ significantly across different subcategories. NIFTP changed the ROM of AUS-A and AUS-C&A, since both NIFTP and FN have microfollicles.

Indeterminate thyroid nodules (TIR3A/TIR3B) according to the new Italian reporting system for thyroid cytology: A cytomorphological study

OBJECTIVE

The Italian reporting system for thyroid cytology classifies indeterminate lesions as TIR3A (low risk) or TIR3B (high risk) and is meant to provide practical guidance rather than a detailed consideration of morphological features. We aimed to assess which cytological features have the most diagnostic value and whether they are effective in classifying nodules as either TIR3A or TIR3B and in predicting histological outcomes.

METHODS

Thyroid fine-needle aspirates from 111 indeterminate nodules were reviewed blinded to clinical information, TIR3A/TIR3B classification, and histology in order to assess which cytological features (pooled into artefacts, smear background, architectural and nuclear atypia, and oncocytes) differentiate TIR3A from TIR3B, and benign from malignant histological outcomes.

RESULTS

Of the cytological features examined, those specific for TIR3B included high cellularity, nuclear atypia, oncocyte predominance and transgressing vessels. Features specific for TIR3A included artefacts, low cellularity and oncocyte sparseness. Other features, such as microfollicules/trabeculae, were non-specific. Due to the different distributions of these features, three TIR3B subgroups were identifiable: follicular lesions with oncocytic changes, pure follicular lesions, and follicular lesions with nuclear atypia, whereas no subgroups were identifiable in TIR3A. Nuclear atypia was a significant indicator of malignancy, whereas oncocyte predominance was not a reliable predictor of malignancy. High cellularity and microfollicules/trabeculae were not indicative of any histological outcome.

CONCLUSIONS

The majority of the assessed features were good predictors of histological outcomes. The TIR3A category included undefined nodules due to the absence of characterising features, whereas the TIR3B category included nodules with a greater number of distinguishing features.

Risk of Malignancy According to the Sub-classification of Atypia of Undetermined Significance and Suspicious Follicular Neoplasm Categories in Thyroid Core Needle Biopsies

The objective of this study was to evaluate the risk of malignancy (ROM) associated with atypia of undetermined significance (AUS) and suspicious follicular neoplasm (SFN) core needle biopsy (CNB) categories after further sub-classification. Data from 2267 thyroid nodules evaluated by ultrasound-guided CNB, from January to December 2015, were retrospectively reviewed. AUS nodules (n = 556) were sub-classified as follows: (1) architectural atypia (AUS-A; n = 369, 66.4%), (2) cytologic atypia (AUS-C; n = 35, 6.3%), (3) cytologic/architectural atypia (AUS-C/A; n = 85, 15.3%), or (4) oncocytic atypia (AUS-O; n = 67, 12.1%). SFN nodules (n = 172) were sub-classified as follows: (1) architectural atypia only (SFN-A; n = 110, 64%), (2) cytologic/architectural atypia (SFN-C/A; n = 24, 14%), or (3) oncocytic atypia (SFN-O; n = 38, 22%). Diagnostic surgery was performed in 162 (30.2%) AUS cases and 105 (61%) SFN cases. The ROM of each sub-category was evaluated. The overall ROM was 15.3-52.5% in AUS nodules and 35.5-58.1% in SFN nodules. The ROM was higher in the AUS-C (22.9-88.9%) and AUS-C/A (32.9-90.3%) groups than AUS-A (11.9-40%) and AUS-O (7.5-41.7%). In the SFN category, ROM in the SFN-C/A group was also higher than SFN-A or SFN-O (37.5-75%, 40-57.9%, and 21.1-47.1%, respectively). Our study shows that the ROM was higher in AUS or SFN sub-categories with cytologic atypia than those without cytologic atypia. Because of the heterogeneous nature of AUS and SFN categories, sub-classification may be a more effective approach for risk stratification, allowing optimal management of patients with thyroid nodules.

Diagnostic Performance of Ultrasound Patterns by K-TIRADS and 2015 ATA Guidelines in Risk Stratification of Thyroid Nodules and Follicular Lesions of Undetermined Significance

OBJECTIVE. The objective of our study was to assess the malignancy rates of thyroid nodules in the cytologically determined subclass of atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) and to assess the diagnostic performance of ultrasound (US) patterns defined by the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and the 2015 American Thyroid Association (ATA) guidelines for risk stratification of AUS/FLUS nodules. MATERIALS AND METHODS. From January 2010 to December 2016, 1340 thyroid nodules were diagnosed as AUS/FLUS via fine-needle aspiration biopsy. Of these, 683 cytopathologically confirmed nodules were included in this study. Each nodule was assigned to a category and US pattern, as defined by the K-TIRADS and ATA guidelines. US patterns were compared between benign and malignant nodules, and malignancy rates were calculated according to the subclasses of AUS/FLUS nodules and the K-TIRADS and ATA guidelines. Predictors of malignancy were assessed using logistic regression analysis. RESULTS. The overall malignancy rate of AUS/FLUS nodules was 47.4% (324/683). There were significant differences in malignancy risk among the subclasses (p = 0.001). There were significant differences in malignancy rates according to US patterns, K-TIRADS categories, and ATA categories (p < 0.001). The malignancy rates in the K-TIRADS categories of benign, low, intermediate, and high suspicion were 0%, 1.99%, 34.66%, and 89.00%, respectively (p < 0.001). The malignancy rates in the ATA categories of benign, very low, low, intermediate, and high suspicion were 0%, 0%, 3.33%, 33.54%, and 87.67% (p < 0.001). CONCLUSION. AUS/FLUS nodules with a final diagnosis of malignancy had significantly higher rates of suspicious US features and different K-TIRADS and ATA categories than benign nodules. US categories by K-TIRADS and ATA guidelines can be useful in predicting malignancy and risk stratification, and management planning can be adjusted according to US pattern.

Rethinking Malignancy Risk in Indeterminate Thyroid Nodules with Positive Molecular Studies: Southern California Permanente Experience

Objectives

To recognize that thyroid nodules with atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS; Bethesda III) have different risks of malignancy based on genetic mutation and to consider molecular testing of nodules with AUS/FLUS to help avoid unnecessary morbidity or cost.

Study Design

Retrospective cohort study.

Setting

Multiple locations within Southern California Permanente Medical Group.

Subjects and Methods

Patients included those with indeterminate thyroid nodules and AUS/FLUS on 2 separate fine-needle aspirations with positive ThyGenX testing from 2014 to 2017 who underwent thyroid surgery. Patients were classified as having benign or malignant disease. Noninvasive follicular thyroid neoplasm with papillary-like nuclear features was considered benign.

Results

A total of 231 patients had repeat AUS/FLUS with positive molecular testing and surgery. The most frequent type of malignancy was papillary carcinoma, followed by follicular carcinoma. The overall prevalence of malignancy in nodules with mutations was 74.0%, although there was considerable variation: BRAF = 100%, RET = 100%, PAX8-PPARγ = 84.6%, HRAS = 70.7%, NRAS = 63.4%, and KRAS = 33%—a statistically significant finding ( P < .001).

Conclusions

Not all molecular mutations in thyroid nodules with AUS/FLUS have a high risk of malignancy. Of note, patients with BRAF and RET mutations in our population had a 100% risk of malignancy. Patients with PAX, HRAS, or NRAS mutations had a high risk of malignancy, while patients with KRAS mutations had a lower risk of malignancy. Further studies are needed to determine if the presence of certain molecular mutations can help personalize care and aid in the decision for thyroid surgery.

Italian consensus for the classification and reporting of thyroid cytology: the risk of malignancy between indeterminate lesions at low or high risk. A systematic review and meta-analysis

BACKGROUND

Italian consensus for the classification and reporting of thyroid cytology has proposed to discriminate the cancer prevalence of high (Tir 3B) vs. low (Tir 3A) risk indeterminate nodules. To obtain more robust evidence on this topic, we performed a meta-analysis of the Odds Ratio (OR) of malignancy of Tir 3B vs. Tir 3A nodules.

METHODS

A comprehensive literature exploration of online databases was conducted until May 2018. Original articles reporting histology of nodules cytologically classified as Tir 3A and Tir 3B were eligible. Pooled cancer prevalence in Tir 3A and Tir 3B, and OR of Tir 3B vs. Tir 3A were calculated.

RESULTS

The search revealed 95 articles, and 10 were included for the meta-analysis. Overall, 1168 indeterminate lesions were reported (441 Tir 3A and 727 Tir 3B), of which 391 were cancers. The pooled cancer prevalence was 17% in Tir 3A and 47% in Tir 3B. The OR of Tir 3B vs. Tir 3A was 4.24 (95% CI 2.75 to 6.53) with mild heterogeneity and without publication bias. When we considered non-invasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP) as non-malignant, cancer rate was lower, and OR of Tir 3B against Tir 3A was 2.93 (95% CI 1.60 to 5.37), with no heterogeneity but with publication bias.

CONCLUSIONS

The Italian system for thyroid cytology is reliable to assess indeterminate lesions at low and high risk, being Tir 3B associated with a cancer risk significantly higher than Tir 3A, also when considering NIFTP as non-malignant entity.

Tumor Growth Rate Does Not Predict Malignancy in Surgically Resected Thyroid Nodules Classified as Bethesda Category III with Architectural Atypia

BACKGROUND

It is unknown whether the growth of thyroid nodules with a Bethesda category III cytology (atypia of undetermined significance [AUS]) is predictive of malignancy, especially in cases with architectural atypia (AUS-A). This study evaluated whether tumor growth rates can help distinguish malignant from benign nodules in the AUS-A subcategory.

METHODS

This retrospective, single-center cohort study included 172 patients who underwent diagnostic thyroid surgery because of a nodule with a cytological diagnosis of AUS-A. The growth kinetics of nodules was assessed by serial preoperative neck ultrasonography over a median follow-up of 52.6 months (range 12.7-198.3 months).

RESULTS

Pathologic examinations showed that 112 (65%) and 60 (35%) patients had benign and malignant nodules, respectively. The largest diameter and volume of both benign and malignant nodules increased gradually (p < 0.001). However, there was no significant difference in the growth rates of benign and malignant nodules based on the largest diameter (p = 0.132) and volume (p = 0.200). The time to tumor growth curves and estimated median time to significant tumor growth from baseline were not significantly different in malignant nodules compared to benign nodules (p = 0.458 and p = 0.568, respectively). The relative risk (RR) of malignancy of growing and stable nodules did not differ significantly based on the largest diameter (RR = 0.5; p = 0.064) and volume (RR = 0.9; p = 0.748).

CONCLUSIONS

The size of thyroid nodules classified as AUS-A increased linearly, regardless whether these nodules were benign or malignant. These results suggest that growth kinetics on serial preoperative neck ultrasonography cannot predict malignancy in the AUS-A subcategory.

A Proposal for Separation of Nuclear Atypia and Architectural Atypia in Bethesda Category III (AUS/FLUS) Based on Differing Rates of Thyroid Malignancy

Objectives

Bethesda category III (atypia of undetermined significance/follicular lesion of undetermined significance) includes sparsely cellular specimens with nuclear atypia (3N) and/or architectural atypia (3A). This study investigates whether the two types of atypia have different rates of malignancy (ROMs).

Methods

Cytologic and histologic diagnoses of resected thyroid nodules were recorded. ROM was calculated for all Bethesda categories and for 3N and 3A subcategories. Possible noninvasive follicular thyroid neoplasms with papillary-like nuclear features were reviewed and removed from malignancies, and ROM was recalculated.

Results

A total of 1,396 nodules were included. ROM of 3N (33.3%-26.0%) was higher than 3A (7.7%-5.0%) (P < .0001) and was similar to suspicious for follicular neoplasm (25.0%-20.3%) (P = .3). ROM of 3A approached benign (2.4%-1.5%) (P = .02).

Conclusions

Strong consideration should be given to separating 3N (nuclear atypia with higher risk for papillary thyroid carcinoma) from 3A (architectural atypia with higher chance of being benign) to convey different ROMs.

Updates in Thyroid Cytology

Genomic, clinical, and pathologic studies have prompted a more risk-stratified approach to the management of patients with thyroid nodules. The recent nomenclature change concerning noninvasive follicular thyroid neoplasm with papillary-like nuclear features reflects the clinical trend toward conservative treatment choices for carefully selected low-risk thyroid neoplasms. These developments have occurred in parallel with a growing array of molecular tests intended to improve clinical triage for patients with indeterminate fine needle aspiration diagnoses. This review discusses the implications of the nomenclature revision on the interpretation of thyroid fine needle aspiration and updates available ancillary molecular tests for thyroid fine needle aspirations.

Cytologic Diagnosis of Oncocytic Neoplasms of the Thyroid Gland: The Importance of the Clinical Scenario

It is a diagnostic challenge to differentiate benign and malignant thyroid neoplasms made up of Hürthle (or oncocytic) cells on cytologic material. They are large, polygonal cells with marked eosinophilic, granular cytoplasm reflective of overly abundant mitochondria. These cells commonly occur in nodular goiters and dominant adenomatous or hyperplastic nodules though they may also be the predominant component of neoplastic lesions. There are significant controversies concerning the optimal management of patients with oncocytic cell carcinoma. This review provides an overview of the most significant studies addressing the distinction between benign and malignant Hürthle cell lesions on cytology and histology.

Prevalence and associated malignancy of Bethesda category III cytologies of thyroid nodules assigned to the "cytological atypia" or "architectural atypia" groups

OBJECTIVE

To ascertain the prevalence of Bethesda category III cytologies and their malignancy rate, and to analyze differences in the second cytology, malignancy rate, type of carcinoma, and TNM stage between the cytological atypia (CA) and architectural atypia (AA) groups.

PATIENTS AND METHOD

A retrospective study of 973 biopsies. Bethesda category III cytologies were classified as CA when nuclear atypia was seen but they were not diagnostic or suspicious of malignancy, and as AA when smears had few cells but had a predominantly microfollicular pattern and minimal or absent colloid. The cytological and pathological results were correlated.

RESULTS

There were 87 (8.9%) Bethesda category III cytologies (34 CC, 53 AA). Second cytologies were performed in 23 patients (16 with CA, 7 with AA), and a benign result was found in 68.7% of CA and 71.4% of the AA group. Sixty-four patients (23 CA, 41 AA) underwent surgery and 15 of these (23.4%) had a malignant disease: 39.1% CA vs 14.6% AA (P=.029). There was a false negative result in the CA group. The follicular variant of papillary thyroid carcinoma was the most common malignancy (60%). There were no differences in type of carcinoma or TNM stage between CA and AA patients.

CONCLUSIONS

The reported prevalence of Bethesda category III cytologies was as expected. The malignancy rate was significantly higher in the CA group, but there were no differences in the result of the second cytology, type of carcinoma found, or TNM stage. The division of Bethesda category III cytologies is useful to provide a better stratification of the risk of malignancy.

Role of Strain Elastography and Shear-Wave Elastography in a Multiparametric Clinical Approach to Indeterminate Cytology Thyroid Nodules

Background

In thyroid nodules with indeterminate cytology, further clinical assessment aimed at ruling out malignancy is often mandatory. Ancillary imaging techniques and genetic mutation analysis can improve the risk stratification of such lesions, thereby facilitating the clinician’s decision to undertaken surgery or simple follow-up. The aim of this study was to evaluate the diagnostic performance of shear-wave elastography (SW), strain elastography (ELX 2/1), conventional ultrasound (US), contrast-enhanced ultrasound (CEUS), and BRAF V600E mutation analysis in the aforementioned lesions.

Material/Methods

We enrolled 81 patients, each with 1 indeterminate-cytology thyroid nodule. Thyroid function, thyroperoxidase antibodies and calcitonin were known in each case. SW, ELX 2/1, US, CEUS, and BRAF mutation analysis were subsequently performed, followed by a second FNAB. If the lesion was not downgraded to benign, surgery was recommended and histological reports collected.

Results

There were 28 nodules (34%) that proved benign on the second FNAB; 38 nodules (47%) underwent surgery (17 benign, 21 malignant), and 15 nodules (19%) refused surgery. The only techniques related to histological outcome were US (AUC=0,766), ELX 2/1 (AUC=0.701), and BRAF analysis (AUC=0.762). ELX 2/1 and SW reports were not correlated with each other (P=0.45). A scoring system taking into account all the variables considered performed better than the single variables alone (AUC=0.831).

Conclusions

In indeterminate-cytology thyroid lesions, repeating FNAB can avoid unnecessary surgery. ELX 2/1 seems to perform better than SW in distinguishing malignancy; these techniques could, however, be complementary in describing such lesions. A multiparametric approach appears the most accurate in predicting nodule histology.