Atypia of undetermined significance on thyroid fine needle aspiration: surgical outcome and risk factors for malignancy

Rates and Predictors of Malignancy in Bethesda III and IV Thyroid Nodules: A Prospective Study

AIM

Thyroid nodules, based on high-resolution ultrasonography (HRUS), are among the most common endocrine abnormalities that affect the general population because of their high estimated prevalence rates. Fine needle aspiration cytology (FNAC) is a safe, cost-effective modality to differentiate between benign and malignant thyroid nodules based on the Bethesda System for Reporting Thyroid Cytopathology (BSRTC), thus avoiding unnecessary surgery. However, categories III and IV of BSRTC remain a controversial issue in clinical practice, encompassing a wide range of risks of malignancy. Hence, our study aimed to assess the malignancy rates of thyroid nodules classified as Bethesda III and IV categories as evidenced by post-thyroidectomy histopathology; study the association between the American College of Radiologists Thyroid Image Reporting and Data System (ACR-TIRADS) score of these two categories and the postoperative histopathological analysis; and study the predictors of malignancy in these two categories.

MATERIALS AND METHODS

A prospective study was conducted on 242 patients who underwent FNAC throughout the study from December 2022 to August 2023. All patients who performed FNAC were primarily subjected to history taking, clinical examination, thyroid-stimulating hormone (TSH), thyroid autoantibodies (antithyroglobulin (anti-TG) and thyroid peroxidase antibodies (TPO Abs)), and HRUS with a further categorization of thyroid nodules according to the ACR-TIRADS scoring system. The cytological aspirates were categorized according to the BSRTC. Patients with Bethesda III and IV categories were resorted to surgery according to clinical factors, sonographic features, and patients' preferences.

RESULTS

A total of 17 cases with Bethesda III and 65 patients with Bethesda IV were included. Seventy-one out of 82 patients (86.6%) underwent surgical intervention. The proportions of malignant nodules classified as TIRADS-2, TIRADS-3, TIRADS-4, and TIRADS-5 scores were 0.0, 4.5 (n=1/22), 22.7 (n=5/22), and 72.7% (n=16/22), respectively. The rate of malignancy was 18.2% (n=2/11) among class III and 33.3% (n=20/60) among class IV-categorized Bethesda thyroid nodules. In univariate logistic regression analysis, age ≥ 40 years, body mass index ≥ 30 kg/m², higher TSH, positive anti-TG antibodies, radiation exposure, irregular borders, marked hypoechogenicity, ill-defined margins, microcalcifications, solid consistency, taller than wide growth, solitary nodule, and nodule size > 2 cm, and suspicious lymph nodes were associated with higher malignancy risk. In multivariate regression analysis, positive anti-TG Abs, radiation exposure, irregular borders, taller-than-wide growth, hypoechogenicity, calcifications, and solid consistency remain to be independent predictors of malignancy.

CONCLUSION

The malignancy rates of Bethesda class III and IV nodules in this study met the estimated malignancy risk proposed by BSRTC. TIRADS scores 4 and 5 confer a higher risk of malignancy in Bethesda III and IV thyroid nodules. Positive thyroglobulin antibodies and radiation exposure are independent factors of malignancy in Bethesda III and IV nodules. Moreover, ultrasound features, including irregular borders, taller-than-wider growth, hypoechogenicity, calcifications, and solid consistency, are associated with increased malignancy risk and should be considered in the surgical selection of patients.

The predictive value of hematologic parameters in the risk of thyroid malignancy in cases with atypia/follicular lesion of undetermined significance

BACKGROUND

Atypia/follicular lesion of undetermined significance (AUS/FLUS) is still the most challenging category in the Bethesda System for Reporting Thyroid Cytopathology. Therefore, the aim of the current study was to investigate the value of the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and mean platelet volume (MPV) in predicting malignancy in cases with AUS/FLUS nodules.

METHODS

A total of 200 patients with AUS/FLUS nodules who underwent thyroidectomy were included in this study. Preoperative hemogram parameters, ultrasonographic findings, fine-needle aspiration results, and postoperative final histopathological diagnoses of the patients were recorded retrospectively.

RESULTS

Thyroid malignancies were detected in 122 of the patients (61.0%). Patients in the benign group (BG) were older than those in the malignancy group (MG) (52.0 ± 11.3 vs. 45.9 ± 12.3 years, p  < 0.001). The median TSH values of the two groups were comparable. Statistically significant differences were obtained between the two groups in respect of mean WBC of 7.53 ± 1.44 in MG and 6.87 ± 1.35 (10³/mm³) in BG, mean neutrophil of 4.65 ± 1.12 in MG and 3.95 ± 0.99 (10³/mm³) in BG, and median NLR of 2.18 (0.71-4.57) in MG and 1.75 (0.80-3.42) in BG (p  < 0.001). The median PLR and MPV values of the two groups were similar. When NLR cut-off point was designated as 2.24, the accuracy of NLR in distinguishing malignancy from the benign condition was 0.65 in ROC analysis (area under the curve, 0.665; specificity, 0.808; sensitivity, 0.492).

CONCLUSION

High NLR values may provide limited help in predicting thyroid malignancy in the AUS/FLUS nodule population, while PLR and MPV are not reliable parameters.

Surgical Outcome and Malignant Risk Factors in Patients With Thyroid Nodule Classified as Bethesda Category III

Background

Thyroid nodules are a very common finding in the general population. Fine-needle aspiration (FNA) has been recommended as the initial test for the evaluation of thyroid nodules. The trend on reporting as atypia of undetermined significance (AUS) has been significantly increased, but the malignant risk is still controversial among different studies. The aim of this study is to investigate the malignancy risk of thyroid nodules reported as Bethesda category III (AUS/FLUS) on initial FNA.

Method

We reviewed 272 papillary thyroid cancer (PTC) patients with suspicious thyroid nodules who underwent fine-needle aspiration and received surgical treatment during 2019 to 2020.

Results

One hundred ten (40.4%) patients were diagnosed with PTC. Multivariate analysis showed that microcalcification (p = 0.037, OR = 2.260, 95% CI: 1.051-4.860), shape (p = 0.003, OR = 4.367, 95% CI: 1.629-11.705), diameters (p = 0.002, OR = 0.278, 95% CI: 0.123-0.631), anti-thyroglobulin antibodies (TGAb) (p = 0.002, OR = 0.150, 95% CI: 0.046-0.494), anti-thyroid peroxidase antibody (A-TPO) (p = 0.009, OR = 4.784, 95% CI: 1.486-15.401), and nodule goiter (p < 0.001, OR = 0.100, 95% CI: 0.046-0.217) were independent malignant risk factors in patients with thyroid nodule classified as Bethesda category III.

Conclusion

In this study, malignant risk factors in patients with thyroid nodule classified as Bethesda category III were significantly associated with preoperative serum TGAb, A-TPO, microcalcification, irregular shape, and nodule diameters. Nodules with malignant factors should be carefully elevated; surgery may be the better option for those patients.

Atypia and Follicular Lesions of Undetermined Significance in Subsequent Biopsy Result: What Clinicians Need to Know

Atypia and follicular lesions of undetermined significance (AUS/FLUS) is the most controversial category of The Bethesda System. The risk of malignancy (ROM) in this group is estimated as 5–15%, however, the occurrence of two or more subsequent biopsy results with AUS/FLUS diagnosis makes these clinical situations more complex. We evaluated the ROM and prognostic value of aggressive ultrasound (US) features in 342 patients with thyroid nodules (TNs) with subsequent biopsy results of AUS/FLUS. We assessed US features and compared them with the final histopathological diagnosis. Overall, 121 (35.4%) individuals after first AUS/FLUS diagnosis underwent surgery and 221 (64.6%) patients had repeated biopsies. The ROM after first, second, and third biopsies with subsequent AUS/FLUS diagnosis were 7.4%, 18.5%, and 38.4% respectively. We demonstrated significantly higher rates of occurrence of aggressive US features in patients with malignancy (p < 0.0001). The age <55 years old was also a significant risk factor for TC (p = 0.044). Significant associations were found between aggressive US features and malignancy in patients after first diagnosis of AUS/FLUS (p < 0.05). The juxtaposition of US features with the number of biopsy repetitions of TN with consecutive AUS/FLUS diagnoses may simplify the decision-making process in surgical management. Two or three consecutive biopsy results with AUS/FLUS diagnosis increases the ROM.

The comparison of the histopathological results of the thyroid fine-needle aspiration biopsies in the 795 patients with thyroidectomy

BACKGROUND

We aimed to evaluate the effectiveness of preoperative fine-needle aspiration biopsies (FNAB) by the postthyroidectomy pathology results.

METHOD

Seven hundred and ninety-five patients with FNAB and following thyroid operations which have been performed between April 2008 and December 2019 were included in this study. By comparing the results of the FNAB and final pathologies, the specificity, sensitivity, FNR, false positivity ratio (FPR), accuracy and also the effect of nodule diameter on these have been evaluated. In Bethesda III subgroup according to FNAB, we investigated the malignancy rates and in whom this risk has been increased more.

RESULTS

In our study, the sensitivity of FNAB is 73.40%, the specificity is 95.33%, the accuracy is 91.81%, FNR is 26.60% and FPR is 4.67%. In the patients with nodules ≥4 cm and < 4 cm respectively, we calculated the sensitivity 20.0% vs 79.76%, specificity 95.73% vs 95.19%, accuracy 89.82% vs 92.78%, FNR 80.0% vs 20.24%, FPR 4.27% vs 4.8%.

CONCLUSION

Thyroid FNAB is an easy procedure with a high specificity and sensitivity. Nevertheless, when the nodule diameter was ≥4 cm, increased FNR and decreased sensitivity should be kept in mind while evaluating the patients.

Atypia of undetermined significance/follicular lesion of undetermined significance: Asian vs. non-Asian practice, and the Singapore experience

The Bethesda System for Reporting Thyroid Cytopathology has paved the way for comparisons of the practice of thyroid cytology in many different regions. However, there have been comparatively few studies documenting differences between Asian and non-Asian practice. Here, we aim to compare a few key parameters between the two regions, focusing on the indeterminate category of atypia of undetermined significance (AUS)/follicular lesion of undetermined significance (FLUS). We compared its incidence, resection rates (RRs), risk of malignancy (ROM), rate of repeat fine needle aspiration (rFNA), ROMs of cytomorphologic subcategories of nuclear atypia (AUS-N) vs. architectural atypia (AUS-A), and, finally, the incidence of papillary thyroid carcinoma (PTC) vs. follicular neoplasms (FNs) in resected AUS/FLUS cases in Asian and non-Asian regions. Where possible, these metrics were compared with the Singapore experience from a tertiary referral institution. While the incidence of AUS/FLUS was similar in both regions, we found geographical differences in the RRs and ROMs, which may reflect a higher collective threshold for surgery in Asian countries. However, both cohorts showed higher ROMs in the AUS-N subcategory as compared to the AUS-A subcategory, supporting the subclassification of the AUS/FLUS based on the presence of nuclear atypia. We also observed a higher incidence of AUS-N coupled with a higher incidence of PTC in resected AUS/FLUS nodules in Asian cohorts, while AUS-A and follicular-patterned neoplasms featured more prominently in the non-Asian cohorts. These incidences may account for the starkly different molecular approaches that we noted-in Asian (chiefly Korean and Chinese) centers, BRAF mutational analysis was favored, while gene panels and gene expression classifiers were more frequently applied in non-Asian centers (chiefly in the United States of America). Overall, the data from Singapore appears more closely aligned to non-Asian trends, despite its geographical location in Southeast Asia and its predominantly Asian population. We conclude that there is significant heterogeneity in the outcomes of the AUS/FLUS categories between and within regions, which is only partially explained by regional variations, and may also reflect different regional diagnostic and management practices. This highlights the importance of understanding the local context in the interpretation of indeterminate Bethesda categories, rather than adopting a "one-size fits all" approach.

Can Repeat Biopsies Change the Prognoses of AUS/FLUS Nodule?

OBJECTIVE

Experience with atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS) showed that this category exhibited a marked variability in incidence and malignant outcome in resection specimens. We aimed to determine the utility of repeated fine-needle aspiration biopsies (FNABs) and ultrasonography to determine the malignancy rate in AUS/FLUS nodules.

METHODS

23,587 nodules were biopsied, and 1,288 had at least one AUS/FLUS cytology. Ultrasonographic features including solid hypoechoic status, irregular margins, microcalcifications, nodule taller than wider, or an extrathyroidal extension were also recorded. Nodules for which only 1 FNAB revealed AUS/FLUS cytology were termed Group 1; nodules that underwent 2, 3, and 4 FNABs were termed Groups 2, 3 and 4, respectively. We compared these groups according to malignancy rates.

RESULTS

576 of nodules underwent only 1 FNAB (Group 1); 505, 174, and 33 underwent 2 (Group 2), 3 (Group 3), and 4 FNABs (Group 4), respectively. Fifty-six (30.6%), 45 (27.3%), 18 (30%), and 5 (33.3%) of Groups 1-4 were malignant, respectively. The risk of malignancy was similar in each group (p > 0.05). Suspicious ultrasonographic features were encountered in malignant nodules more than benign nodules (p < 0.05, for each).

CONCLUSION

Repeat biopsy of AUS/FLUS nodules did not enhance the identification of malignancy. Ultrasonographic features may be a better guide for the decision of either surveillance or diagnostic surgery.

THE ROLE OF THYROID FINE-NEEDLE ASPIRATION CYTOLOGY IN THE TREATMENT AND FOLLOW-UP OF THYROID NODULES IN THE PEDIATRIC POPULATION

Objective

Thyroid fine-needle aspiration (FNA) and cytology is a reliable diagnostic method used in the assessment of malignancy when evaluating thyroid nodules, in conjunction with clinical and ultrasonographic findings. The aim of this study is to compare clinical, ultrasonographic, cytological and histopathological findings in children who underwent thyroid FNA.

Methods

Subjects comprised 80 patients (52 female) aged 13.7±2.8 years at the time of FNA who where evaluated for thyroid nodules. Clinical, ultrasonographic and cytological findings of patients were evaluated retrospectively.

Results

Autoimmune thyroiditis was present in 30% and history of radiotherapy to the head or neck in 10%. The cytological diagnosis of patients included: inadequate or hemorrhagic sample in 10%; benign in 42.5%; atypia or follicular lesion of undetermined significance (AUS/FLUS) in 15%; suspicion of follicular neoplasia (SFN) in 7.5%; suspicion of malignancy (SM) in 8.8%; and malignant in 16.3%. Thirty-seven patients underwent thyroidectomy. Malignancy rates for histopathologic follow-up were 75%, 85.7% and 100% for SFN, SM and malignant categories, respectively. Only one benign and two AUS/FLUS FNAs were found to be malignant on histopathological examination. Among patients who had received radioiodinetherapy, 87.5% had malignancy. In this study, the sensitivity of FNA was 96%, specificity 50%, positive predictive value 90.9%, negative predictive value 75%, and diagnostic value of FNA was 89.2%.

Conclusion

Thyroid FNA results were highly compatible with histopathological examination. Sensitivity, positive predictive value and diagnostic value of FNA were high.

WHICH FACTORS ARE ASSOCIATED WITH MALIGNANCY IN THYROID NODULES CLASSIFIED AS BETHESDA CATEGORY 3 (AUS/FLUS) AND HOW DO THEY INFLUENCE THE PATIENT'S MANAGEMENT?

Background

Thyroid nodules are a common pathology worldwide. Fine needle aspiration biopsy (FNAB) is an important diagnostic method for the investigation of malignancy in thyroid nodules. However, according to the Bethesda System used to classify the results, patients with atypia of undetermined significance/follicular lesion of undetermined significance (AUS / FLUS) may not be classified as benign or malignant. Therefore, it may be necessary to determine some clinical risk factors to apply the best treatment in these patients.

Aim

To determine the factors that increase the risk of malignancy in this patient group.

Methods

A retrospective study including 138 patients with an FNAB categorized as AUS/FLUS and operated between June 2015-September 2018. Demographical, Laboratory (TSH) and Ultrasound variables (number, size and characteristics of nodules) of the patients were compared among postoperative histopathological results.

Results

Hypo-echoic structure, microcalcification and irregular margin of the nodules were detected to be associated with malignancy in patients with FNAB results of AUS/FLUS (p <0.001).

Conclusion

We suggest that surgical treatment should be considered if the patients have nodules with the hypo-echoic structure, microcalcification and irregular margin with an FNAB histopathological result of AUS / FLUS.

Cytomorphologic, Imaging, Molecular Findings, and Outcome in Thyroid Follicular Lesion of Undetermined Significance/Atypical Cell of Undetermined Significance (AUS/FLUS): A Mini-Review

OBJECTIVES

Since the introduction of the entity of "Atypical cell of undetermined significance /follicular lesion of undetermined significance" (AUS/FLUS) by The Bethesda System for Reporting Thyroid Cytology (TBSRTC) in 2007, there have been many published studies about the cytomorphologic criteria, subclassification, outcome, and management of patients with the diagnosis of AUS/FLUS. There have been many studies in different aspects of this indeterminate category, i.e., cytologic and molecular findings, ultrasonographic findings, and in some instances even core-needle biopsy to address a better and safer way of the management of patients with this fine-needle aspiration cytology diagnosis. The second edition of TBSRTC and the 2015 American Thyroid Association guidelines provide an update on the follow-up and management of AUS/FLUS. A multidisciplinary team consisting of pathologists, endocrinologists, surgeons, and radiologists should be involved in the diagnosis and management of AUS/FLUS, and all of them should be aware of the heterogeneity of this lesion for the prediction of the treatment and outcome.

STUDY DESIGN

In this review, we consider different research platforms (2008-2017) to find the best and key reports for the above-mentioned challenging aspects of AUS/FLUS.

CONCLUSION

AUS/FLUS is now a well-defined group of thyroid lesions, which can be most accurately diagnosed and managed with cytomorphology, molecular, and ancillary studies.

Thyroid cancer detection rate and associated risk factors in patients with thyroid nodules classified as Bethesda category III

Background Ultrasound guided fine-needle aspiration (FNA) is a standard procedure for thyroid nodules management and selecting patients for surgical treatment. Atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS), as stated by The Bethesda System for Reporting Thyroid Cytopathology, is a diagnostic category with an implied malignancy risk of 5-15%. The aim of our study was to review cytology and histopathology reports, as well as clinical and ultrasound data, for thyroid nodules reported as AUS/FLUS, in order to evaluate the malignancy rate and to assess factors associated with malignant outcome. Patients and methods A total of 112 AUS/FLUS thyroid nodules in 105 patients were evaluated, of which 85 (75.9%) were referred to surgery, 21 (18.8%) were followed-up by repeat FNA and 6 nodules (5.3%) were clinically observed. Each was categorized in two final diagnostic groups - benign or malignant, which were further compared to clinical data of patients and ultrasonographic features of the nodules. Results Final diagnosis of malignancy was reached in 35 cases (31.2%) and 77 (68.8%) had benign lesions. The most frequent type of cancer was papillary thyroid carcinoma (PTC) - 58.1% PTC and 25.8% had follicular variant of PTC. Patients' younger age, smaller nodule size, hypoechoic nodule and presence of calcifications were shown to be statistically significant risk factors for malignancy. Conclusions The rate of malignancy for the AUS/FLUS diagnostic category in our study was higher than estimated by the Bethesda System. Clinical and ultrasound factors should be considered when decision for patient treatment is being made.

Predictive Factors of Malignancy in Cytology of Indeterminate Follicular and Hürthle Cell Neoplasms of the Thyroid Gland

The objective of the current study was to determine the risk of malignancy in patients with thyroid nodules with cytology of indeterminate follicular and indeterminate Hürthle cell neoplasm (HN). The cytologic diagnosis of follicular neoplasm (FN) or HN remains a diagnostic challenge. Often, surgery is recommended for such lesions. A retrospective analysis was performed on 80 patients who underwent thyroid surgery following a diagnosis of indeterminate FN and indeterminate HN in thyroid fine-needle aspiration biopsy. Sex; age; family history of thyroid cancer and radiation exposure; coexisting thyroid conditions, such as solitary nodule; multinodularity; cytologic diagnosis; sonographic features; type of surgical treatment; and histopathologic results were recorded. Of the 80 patients, 52 (65%) had FN on fine-needle aspiration biopsy cytology and 28 (35%) had HN. A total of 23 patients (28.7%) had primary thyroid cancers on surgical pathology, and 57 (71.3%) had benign diagnoses. Univariate analysis showed no differences between the benign and malignant groups by sex, nodule size, family history of thyroid cancer, history of radiation exposure, presence of solitary nodule or multinodularity in the nodular features. In multivariate binary logistic regression analysis, the factors that were statistically significant predictors of malignancy were microcalcification [odds ratio (OR), 10.9; 95% confidence interval (CI), 2.18–54.7; P = 0.004], being older than 45 years (OR, 4.2; 95% CI, 1.25–14.63; P = 0.02]. The independent predictors of malignancy in FN and HN are micorcalcification and being older than 45 years, the use of which may predict the risk of thyroid cancer.

Risk stratification of thyroid nodules with Bethesda category III results on fine-needle aspiration cytology: The additional value of acoustic radiation force impulse elastography

To assess the value of conventional ultrasound, conventional strain elastography (CSE) and acoustic radiation force impulse (ARFI) elastography in differentiating likelihood of malignancy for Bethesda category III thyroid nodules. 103 thyroid nodules with Bethesda category III results on fine-needle aspiration cytology (FNAC) in 103 patients were included and all were pathologically confirmed after surgery. Conventional ultrasound, CSE and ARFI elastography including ARFI imaging and point shear wave speed (SWS) measurement were performed. Univariate and multivariate analyses were performed to identify the independent factors associated with malignancy. Area under the receiver operating characteristic curve (Az) was calculated to assess the diagnostic performance. Pathologically, 65 nodules were benign and 38 were malignant. Significant differences were found between benign and malignant nodules in ARFI. The cut-off points were ARFI imaging grade ≥ 4, SWS > 2.94 m/s and SWS ratio > 1.09, respectively. ARFI imaging (Az: 0.861) had the highest diagnostic performance to differentiate malignant from benign nodules, following by conventional ultrasound (Az: 0.606 - 0.744), CSE (Az: 0.660) and point SWS measurement (Az: 0.725 - 0.735). Multivariate logistic regression analysis showed that ARFI imaging grade ≥ 4 was the most significant independent predictor. The combination of ARFI imaging with point SWS measurement significantly improved the specificity (100% vs. 80.0%) and positive predictive value (100 % vs. 72.9%) in comparison with ARFI imaging alone. ARFI elastography is a useful tool in differentiating malignant from benign thyroid nodules with Bethesda category III results on FNAC.

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

BACKGROUND

Indeterminate categories of thyroid cytopathology (categories B-III and B-IV of the Bethesda system) are integrated by a heterogeneous spectrum of cytological scenarios that are generally clustered for analysis and management recommendations. It has been suggested that aspirates exhibiting nuclear atypia have a higher risk of malignancy. This study aimed to assess whether cytologically indeterminate thyroid nodules with nuclear atypia have a significantly higher cancer risk than those without nuclear atypia.

METHODS

On June 30, 2016, PubMed and EMBASE were searched for articles in English or Spanish using a search strategy developed by an endocrinologist and a librarian. Case reports were excluded, and no date limits were used. The references of all included studies were also screened for relevant missing studies. Studies were included if the prevalences of malignancy of cytologically indeterminate thyroid nodules with histological confirmation with and without nuclear atypia were reported. Studies were excluded if they had: (i) nodules suspicious for malignancy; (ii) nodules with non-indeterminate (B-III or B-IV) cytology on repeated biopsy, if performed; (iii) nodules not consecutively evaluated; or (iv) cohorts overlapping with another larger series. Two investigators independently assessed the eligibility and risk of bias of the studies. PRISMA and MOOSE guidelines were followed. Summary data were extracted from published reports by one investigator and independently reviewed by another. Data were pooled using a random-effects model. Heterogeneity was explored using subgroup analysis and mixed-effect model meta-regression. The odds ratio for malignancy of cytologically indeterminate thyroid nodules with nuclear atypia over cytologically indeterminate thyroid nodules without nuclear atypia was calculated.

RESULTS

Of 2571 retrieved studies, 20 were eligible. The meta-analysis was conducted on summary data of 3532 cytologically indeterminate thyroid nodules: 1162 with and 2370 without nuclear atypia. The odds ratio for malignancy in cytologically indeterminate thyroid nodules with nuclear atypia was 3.63 [confidence interval 3.06-4.35]. There was no evidence of publication bias, and heterogeneity was insignificant (I² < 0.01%, p = 0.40).

CONCLUSIONS

Nuclear atypia is a significant indicator of malignancy in cytologically indeterminate thyroid nodules and needs to be standardized and implemented into clinical practice.

Thyroid nodules classified as atypia or follicular lesions of undetermined significance deserve further research: Analysis of 305 surgically confirmed nodules

OBJECTIVE

The objective of the present study was to determine the malignancy risk for nodules categorised as atypia or follicular lesions of undetermined significance atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) and to investigate the predictors of malignancy.

METHODS

All nodules diagnosed as AUS/FLUS on fine needle aspiration (FNAs) performed between January 2011 and December 2015 were retrospectively reviewed. Clinical data, ultrasonographic features, follow-up data and the final pathological results were recorded. After further exclusion, only nodules that underwent surgical excision were included in the final analysis. The malignancy rate and the range of malignancy rates were calculated. Clinical and ultrasound features were examined to determine the predictors of malignancy.

RESULTS

During the study period, FNA was performed on 9938 nodules, and 1019 (10.2%) nodules were diagnosed as AUS/FLUS. After further exclusion, 976 nodules were evaluated. After the initial diagnosis of AUS/FLUS, 139 (14.2%) patients underwent surgery, 518 (53.1%) had repeated FNAs. A total of 305 (31%) had undergone surgical excision at different time points. For surgically confirmed nodules, the malignancy rate after the initial FNA was 34.5% (the lower and upper thresholds for the malignancy rate were 19.3% and 66.3%, respectively), and 37.9% after the repeated FNA. No ultrasound feature was determined as a predictor, whereas age (>55 years) was a predictor for malignancy.

CONCLUSIONS

The overall malignancy rate for nodules diagnosed as AUS/FLUS and the malignancy rate for nodules that underwent repeated FNA after AUS/FLUS were higher than the expected malignancy rates of the National Cancer Institute. It is, therefore, suggested that the current recommendations should be reconsidered.

Ultrasound is helpful to differentiate Bethesda class III thyroid nodules: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Fine-needle aspiration (FNA) is the most dependable tool to triage thyroid nodules for medical or surgical management. However, Bethesda class III cytology, namely "follicular lesion of undetermined significance" (FLUS) or "atypia of undetermined significance" (AUS), is a major limitation of the US-FNA in assessing thyroid nodules. As the most important imaging method, ultrasound (US) has a high efficacy in diagnosing thyroid nodules. This meta-analysis aimed to assess the role of US in evaluating Bethesda class III thyroid nodules.

METHODS

With keywords "Undetermined Significance," "Bethesda Category III," "Bethesda system," "Cytological Subcategory," "AUS/FLUS," "Atypia of Undetermined Significance," and "Ultrasound/US," papers in PubMed, Cochrane Library, Medline, Web of Science, Embase, and Google Scholar from inception to December 2016 were searched. A meta-analysis of these trials was then performed for evaluating the diagnostic value of thyroid ultrasound in Bethesda Category III thyroid nodules.

RESULTS

Fourteen studies including 2405 nodules were analyzed. According to the criteria for US diagnosis of thyroid nodules in each article, with any one of suspicious features as indictors of malignancy, US had a pooled sensitivity of 0.75 (95% CI 0.72-0.78) and a pooled specificity of 0.48 (95% CI 0.45-0.50) in evaluating Bethesda Class III Nodules. The pooled diagnostic odds ratio was 10.92 (95% CI 6.04-19.74). The overall area under the curve was 0.84 and the Q* index was 0.77. With any 2 or 3 of US suspicious features as indictors of malignancy, the sensitivity and specificity were 0.77 (95% CI 0.71-0.83) and 0.54 (95% CI 0.51-0.58), 0.66 (95% CI 0.59-0.73) and 0.71 (95% CI 0.68-0.74), respectively.

CONCLUSIONS

US was helpful for differentiating benign and malignant Bethesda class III thyroid nodules, with the more suspicious features, the more likely to be malignant.

Risk factors associated with malignancy and with triage to surgery in thyroid nodules classified as Bethesda category III (AUS/FLUS)

BACKGROUND

Selection of nodules for surgery diagnosed as Bethesda category III [atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) category] is very important. We aimed at to define the predictive factors for malignancy and factors associated with triage to surgery.

METHODS

The records of all patients with nodules who underwent fine needle aspiration biopsy (FNAB) and classified by Bethesda reporting system as AUS/FLUS between 2011 and 2015 at our institution were reviewed. Univariate and multivariate analysis were performed to select independent factors associated with thyroid cancer and with triage to surgery. Using independent risk factors for malignancy predictive index categories were created.

RESULTS

Of the 485 patients who were classified as AUS/FLUS on initial FNAB, 153 underwent surgery with the associated malignancy rate of 22.8%. The malignancy rates for AUS/FLUS patients with and without repeat FNAB were 37.5% and 16.2%, respectively. Multivariate logistic regression analysis revealed that solid structure, microcalcification, hypoechogenicity, increased vascularization, and irregular margin were found to be significant and independent risk factors associated for malignancy, and solid structure, microcalcifications, increased nodule size (≥2 cm) and younger patient age (<65 years) were associated with triage to surgery.

CONCLUSIONS

Our findings showed that using predictive factors for malignancy in AUS/FLUS category as risk indices, an important proportion of patients (35%) who had nodules without any risk factors could be spared unnecessary surgery. We suggest that predictive indices should be considered for selection of the patients to triage to surgery.

Thyroid nodules with atypia or follicular lesions of undetermined significance (AUS/FLUS): analysis of variables associated with outcome

BACKGROUND

The Bethesda System for Reporting Thyroid Cytopathology is one of the main classification systems for thyroid nodules. It expects that 7% of all fine needle aspiration biopsies will be reported as atypia or follicular lesions of undetermined significance, and 5-15% of these undetermined nodules are malignant. Our study is a retrospective analysis of variables that may be associated with outcome in patients with indeterminate thyroid nodules.

MATERIALS AND METHODS

Patients who underwent thyroidectomy in our institution between 2010 and 2014 were retrieved from the institutional records database. Patient demographics and medical histories were recorded. All ultrasonography reports were examined for nodule features and biochemical blood levels, hormone levels and complete blood counts were recorded.

RESULTS

A total of 103 patient cytopathology reports were regarded as belonging to the undetermined category. Some 35% of patients had malignant nodules. Median preoperative red cell distribution width (RDW) level was 13.6 inthe benign group, while it was 14.3 in patients with malignancy, demonstrating a significant correlation (p=0.003). Only calcification presence was significantly different between benign and malignant groups on ultrasonography (p=0.034).

CONCLUSIONS

Ultrasonography is one of the primary tools for this matter. RDW levels may become another promising tool to predict malignancy.