Large cystic/solid thyroid nodules: a potential false-negative fine-needle aspiration

Consistency in the Distribution of Bethesda System for Reporting Thyroid Cytology Categories Over 9 Years: A Single Institute, Retrospective Study

BACKGROUND

The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) has evolved since it was first introduced in 2009 to become a worldwide accepted cytologic analysis reference, due to its simplicity and reproducibility. To date, the consistency of BSRTC throughout time has yet to be investigated.

METHODS

Retrospective single institution case series with chart review of all patients who underwent fine-needle aspirations for a thyroid nodule in our institution between the years 2010 and 2018 with a documented BSRTC classification. Data collection included demographics, risk factors, sonographic evaluation, nodule size, and final pathology when feasible. The main outcome is the difference in the rates of BSRTC categories benign, atypia of undetermined significance (AUS), follicular neoplasm, suspicious for malignancy, and malignant (BSRTC II-VI, respectively) between the study years.

RESULTS

A total of 2830 thyroid nodules were included. BSRTC II-VI distribution was 83.9% (2373), 8.2%, (232), 2.7% (75), 3.3% (93), and 2.0% (57), respectively. There was no significant change in the overall trend of each BSRTC category distribution throughout the study. There was a significant increase in the benign cytology rate (BSRTC II) in 2011 compared to 2015 and 2018 (76.4% compared to 88.7% and 87.6%, respectively. P < .005) alongside a significant decline in the AUS category rate (BSRTC III) between the same years (13.0% compared to 4.8% and 5.5%, respectively. P < .005).

CONCLUSION

BSRTC showed consistency throughout the study across all observed categories. An overlap between AUS and benign may exist, possibly due to the heterogenic definition of AUS as reflected in the 2023 BSRTC subclassification for AUS.

Do large thyroid nodules (≥4 cm) without suspicious cytology need surgery?

Background

Fine-needle aspiration biopsy (FNAB) is a good diagnostic tool for thyroid nodules; however, its high false-negative rate for giant nodules remains controversial. Many clinicians recommend surgical resection for nodules >4 cm owing to an increased risk of malignancy and an increased false-negative rate. This study aimed to examine the feasibility of this approach and investigate the incidence of malignancy in thyroid nodules >4 cm without suspicious cytology based on medical records in our center.

Methods

This was a retrospective analysis of 453 patients that underwent preoperative FNAB for nodules measuring >4 cm between January 2017 and August 2022 at Severance Hospital, Seoul.

Results

Among the 453 patients, 140 nodules were benign and 119 were indeterminate. Among 259 patients, the final pathology results were divided into benign (149) and cancerous (110) groups, and the prevalence of malignancy was 38.9% in the benign group and 55.5% in the indeterminate group. Among the malignancies, follicular carcinoma and follicular variants of papillary carcinoma were observed in 83% of the cytologically benign group and 62.8% of the indeterminate group.

Conclusion

Preoperative FNAB had high false-negative rates and low diagnostic accuracy in patients with thyroid nodules >4 cm without suspicious cytologic features; therefore, diagnostic surgery may be considered a treatment option.

Risk of malignancy and diagnostic accuracy of fine-needle aspiration biopsy in thyroid nodules with diameters greater than 4 centimeters

Objective

The risk of malignancy and diagnostic accuracy of fine-needle aspiration biopsy (FNAB) of thyroid nodules (TN) with diameters ≥ 3-4 cm remains controversial. However, some groups have indicated surgical treatment in these patients regardless of the FNAB results. We aimed to evaluate the diagnostic accuracy of the FNAB in systematically resected ≥4 cm TN and if the risk of malignancy is higher in these patients.

Subjects and methods

We retrospectively evaluated 138 patients (142 nodules) with TN with diameters ≥4 cm who underwent thyroidectomy.

Results

The FNAB results were nondiagnostic/unsatisfactory (ND/UNS) in 2.1% of the cases and benign in 51.4%. They indicated atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) in 23.9% of cases, follicular neoplasia/suspicious for a follicular neoplasm (FN/SFN) in 9.2%, suspicion of malignancy (SUS) in 8.5%, and malignant in 4.9%. The histopathological analysis after thyroidectomy revealed a thyroid cancer rate of 100% in the FNABs classified as malignant, 33.3% in SUS cases, 7.7% in FN/SFN, 17.6% in AUS/FLUS, and 4.1% in benign FNABs. None of the ND/UNS FNABs were malignant. The global malignancy diagnosis was 14.8% (n = 21). However, the rate of false negatives for FNAB was low (4.1%).

Conclusion

We showed that the risk of malignancy in nodules with diameters ≥4 cm was higher compared to the risk of thyroid cancer in TN in general. However, we found a low rate of false-negative cytological results; therefore, our data do not justify the orientation of routine resection for these larger nodules.

Extent of thyroidectomy: When should hemithyroidectomy be performed? Recommendations from the Francophone Association for Endocrine Surgery, the French Society of Endocrinology and the French Society of Nuclear Medicine

These recommendations, drawn from current data in the medical literature, incorporate the risks of hemithyroidectomy (HT) and total thyroidectomy (TT) and clarify the place of these two procedures in clinical settings. Discussions leading to a consensus were then assessed by the Francophone Association for Endocrine Surgery (Association francophone de chirurgie endocrinienne [AFCE]), along with the French Society of Endocrinology (Société française d'endocrinologie [SFE]), and the French Society of Nuclear Medicine (Société française de médecine nucléaire [SFMN]). The complication rate was twice as high after TT compared to HT. Total thyroidectomy requires life-long thyroid hormone supplementation, whereas such supplementation is required in only 30% of patients after HT. When surgery is indicated for Bethesda category II nodules, and in the absence of any indication for surgery on the contralateral lobe, HT is recommended. In patients with thyroid cancer (TC)≤1cm requiring surgical management or TC≤2cm, in the absence of risk factors for TC and in the absence of pre- or intraoperative detection of extrathyroidal extension, lymph node metastases (cN0) and/or suspected contra-lateral disease, HT is the preferred technique as long as the patient accepts the possibility of TT which might be required when aggressive forms of cancer are detected on definitive cytohistology (extrathyroidal extension, lymphovascular invasion, high-grade histology). For TC measuring between 2 and 4cm, the debate between HT and TT remains open today, although some surgeons tend to prefer TT. In patients with TC>4cm, macroscopic lymph node involvement (cN1), signs of extrathyroidal extension or predisposing factors for TC, TT is the treatment of choice.

Diagnostic accuracy of fine needle aspiration biopsy versus postoperative histopathology for diagnosing thyroid malignancy

INTRODUCTION

Ultrasound-guided fine needle aspiration biopsy (FNAB) is currently widely used for the initial screening of patients with thyroid nodules enabling prevention of unnecessary surgery. The purpose of this study was to retrospectively analyse the diagnostic accuracy of thyroid FNAB compared with postoperative histopathology of a large cohort from Azerbaijan.

METHODS

We evaluated the FNAB results of 738 patients who underwent thyroid surgery at the National Centre of Oncology in Azerbaijan. The measures of diagnostic accuracy were calculated for the ultrasound-guided preoperative FNAB results (based on the six diagnostic categories of the Bethesda classification) compared with postoperative histopathologic results (benign or malignant) for correspondent areas.

RESULTS

Considering both DC V and DC VI categories (387 cases) as 'cytologic-positive' and DC II category (72 cases) as 'cytologic-negative', we found 14 false-positive and 10 false-negative results. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy were 97.4%, 86.1%, 96.4%, 81.6% and 94.8%, respectively. Conversely, when considering only the DC VI category as 'cytologic-positive', the sensitivity, specificity, PPV, NPV and diagnostic accuracy of FNA were 93.2%, 100%, 100%, 81.6% and 97.1%, respectively.

CONCLUSIONS

The results of our cohort demonstrated high levels of diagnostic accuracy, supporting FNAB's role as a reliable diagnostic tool in the preoperative evaluation of thyroid nodules. The sensitivity, specificity, NPV, PPV and accuracy of thyroid FNAB in our institution were comparable with those of other institutions.

Sonographic appearances of hobnail papillary thyroid carcinoma: A case report of a rare tumour

Introduction

Hobnail papillary thyroid carcinoma is a rare, recently described papillary thyroid carcinoma variant, with potential for a more aggressive clinical course of disease and poorer prognosis.

Case report

A 53-year-old man presented with a left thyroid mass. The ultrasound features of this mass included a predominantly cystic appearance with mobile internal echoes, vascularised internal septations, and murally based solid material. These ultrasound features were not deemed malignant by classification standards, which led to the patient being managed with active surveillance. However, the mass grew quickly and the patient underwent diagnostic hemithyroidectomy which led to hobnail variant papillary thyroid carcinoma being found on pathology.

Discussion

The ultrasound features of the hobnail variant of papillary thyroid carcinoma have not been previously described in detail in the literature and, in this case, are features that would not be deemed malignant by classification standards. The rapid growth of the mass is what led to clinical suspicion of malignancy and resulted in diagnosis.

Conclusion

The hobnail variant of papillary thyroid carcinoma may not have typical ultrasound findings associated with malignancy. Careful clinical correlation is advised in order to discern this difficult diagnosis and to facilitate appropriate treatment.

Navigating the Debate on Managing Large (≥4 cm) Thyroid Nodules

PURPOSE

Discordant practice guidelines for managing large thyroid nodules may result in unnecessary surgeries and costs. Recent data suggest similar false-negative rates in fine needle aspiration (FNA) biopsies between small (<4 cm) and large (≥4 cm) nodules, indicating that monitoring rather than surgery may be appropriate for large biopsy-negative nodules. We investigated the management of thyroid nodules ≥4 cm to determine the proportion of surgeries not necessary for diagnostic purposes and examined for potential predictors.

METHODS

This was a retrospective cohort study of patients who received a FNA of nodule(s) ≥4 cm between 11/1/2014 and 10/31/2019 at the University of Vermont Medical Center. A surgery was considered unnecessary if the FNA result was benign in the absence of any of the following: compressive symptoms, family history of thyroid cancer in a first degree relative, history of neck irradiation, toxic nodule or toxic multinodular goiter, or substernal extension. Data were analyzed with Wilcoxon rank sum tests, chi square, or Fisher's exact tests.

RESULTS

177 patients had a ≥4 cm nodule during the timeframe and half (54.2%) had surgery. Patients who underwent surgery were significantly younger (51.5 years vs. 62 years; P < 0.001), more likely to report obstructive symptoms (34.4% vs. 12.1%; P < 0.001) and had a larger nodule size (5.0 cm vs. 4.7 cm; P=0.26). Forty-one patients with benign (Bethesda II) FNA results had surgery, all with negative surgical pathology. Thirteen percentage (23/177) of surgeries were potentially not necessary for diagnostic purposes.

CONCLUSION

Approximately half of our patients with ≥4 cm nodules had surgery, with 13% having surgery not necessary for diagnostic purposes revealing opportunities for improving care and costs.

Large thyroid nodules: should size alone matter?

BACKGROUND

The management of thyroid nodules ≥ 4 cm is controversial due to conflicting evidence on the prevalence of malignancy and diagnostic accuracy of fine-needle aspiration cytology (FNAC). Some literature recommends routine excision of large thyroid nodules due to high cytology false negative rates (FNR). We aim to investigate the diagnostic accuracy of FNAC, prevalence of malignancy in large (≥ 4 cm) thyroid nodules compared to nodules < 4 cm, and the clinical and ultrasound characteristics of those large nodules with false negative cytology.

METHODS

This was a retrospective case-log review in a tertiary referral hospital. All thyroid nodules subjected to Ultrasound (US)-guided FNAC by the Interventional Radiology department between December 2011 and November 2017 were included. Data on patient demographics, thyroid US features, cytology findings, and surgical histology were collected and analyzed. Sensitivity, specificity, and FNR were calculated based on FNAC results and final post-operative histology. Factors associated with a false negative result were analyzed using univariate and multivariate analyses.

RESULTS

A total of 4982 nodules were studied, including 4419 < 4 cm and 563 ≥ 4 cm. Malignancy rates were similar in both groups. For nodules ≥ 4 cm, FNAC sensitivity was 40%, specificity 100%, and FNR 6.6% compared to 4.2% in nodules < 4 cm. Within malignant nodules, there was a significantly higher proportion of follicular and Hurthle cell carcinomas in nodules ≥ 4 cm. Amongst nodules ≥ 4 cm, multivariate analysis revealed male gender to be an independent predictor of FNR (OR 3.32; 95% CI 1.29-8.59).

CONCLUSION

Larger nodules ≥ 4 cm have a similar malignancy rate as nodules < 4 cm, and FNAC FNR is low at 6.6%. Management of large thyroid nodules should be individualized based on their clinical, sonographic and cytological features rather than routine surgery.

LEVEL OF EVIDENCE

3.

Current Evaluation of Thyroid Nodules

Thyroid nodules may be discovered in a variety of settings. Familiarity with their management is important for medical specialists. Workup should start with history and physical examination, proceed to laboratory studies, and then to imaging. Nodules are selected for fine needle aspiration (FNA) biopsy based on imaging criteria. Most nodules can be accurately diagnosed on cytopathology, but some may require additional molecular testing to evaluate risk of malignancy. Patients with malignant lesions require additional investigation before referral to an experienced thyroid surgeon. Those who have benign lesions may require monitoring by periodic ultrasound to identify nodules requiring reevaluation.

A Scoring System for Assessing the Risk of Malignant Partially Cystic Thyroid Nodules Based on Ultrasound Features

Objective

To assess the ultrasound (US) features of partially cystic thyroid nodules (PCTNs) and to establish a scoring system to further improve the diagnostic accuracy.

Methods

A total of 262 consecutive nodules from September 2017 to March 2020 were included in a primary cohort to construct a scoring system. Moreover, 83 consecutive nodules were enrolled as an validation cohort from May 2018 to August 2020. All nodules were determined to be benign or malignant according to the pathological results after surgery or ultrasound-guided fine-needle aspiration (US-FNA). The US images and demographic characteristics of the patients were analyzed. The ultrasound features of PCTNs were extracted from primary cohort by two experienced radiologists. The features extracted were used to develop a scoring system using logistic regression analysis. Receiver operating characteristic (ROC) curves were applied to evaluate the diagnostic efficacy of the scoring system in both the primary cohort and validation cohort. In addition, the radiologists evaluated the benign and malignant PCTNs of the validation cohort according to the ACR TI-RADS guidelines and clinical experience, and the accuracy of their diagnosis were compared with that of the scoring system.

Results

Based on the eight features of PCTNs, the scoring system showed good differentiation and reproducibility in both cohorts. The scoring system was based on eight features of PCTNs and showed good performance. The area under the curve (AUC) was 0.876 (95% CI, 0.830 - 0.913) in the primary cohort and 0.829(95% CI, 0.730 - 0.903) in the validation cohort. The optimal cutoff value of the scoring system for the diagnosis of malignant PCTNs was 4 points, with a good sensitivity of 71.05% and specificity of 87.63%. The scoring system (AUC=0.829) was superior to radiologists (AUC= 0.736) in diagnosing PCTNs and is a promising method for clinical application.

Conclusions

The scoring system described herein is a convenient and clinically valuable method that can diagnose PCTNs with relatively high accuracy. The use of this method to diagnose PCTNs, which have been previously underestimated, will allow PCTNs to receive reasonable attention, and assist radiologist to confidently diagnose the benignity or malignancy.

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.

Thyroid Nodules Located in the Lower Pole Have a Higher Risk of Malignancy than Located in the Isthmus: A Single-Center Experience

PURPOSE

The aim of our study is to investigate whether thyroid nodules (TNs) localization has value as a predictor of malignancy. Ultrasonography provides very valuable information in the evaluation of TNs, but it does not correlate perfectly with histopathologic findings. Therefore, studies that will include new diagnostic methods that can improve these unknowns can be welcomed gratefully.

METHODS

This study was carried out retrospectively in a tertiary care center from September 2016 to January 2020. The study included 862 adult patients who have one or more nodules. Ultrasonography of characteristics of nodules such as echogenicity, content, margins, calcifications, size, and localization was recorded. Fine-needle aspiration biopsy (FNAB) was performed on dominant and suspicious 1142 nodules.

RESULTS

The patients were composed of 692 (80.3%) females and 170 (19.7%) males. Compared to nodules located in the isthmus; the malignancy risk increased 8.39 (OR: 8.39 (2.34-30.12), p = 0.001) times in the lower pole, 4.27 (OR: 4.27 (1.16-15.72), p = 0.029), times in the middle pole, 8.09 (OR: 8.09 (2.11-30.94), p = 0.002) times in the upper pole, and 7.63 (OR: 7.63 (1.95-29.81), p = 0.003) times in the nodules covering the whole of the lobe. Although the most nodular location was in the middle pole, the risk of malignancy was less than that in the lower and upper poles.

CONCLUSIONS

Unlike the other localization studies, we found a higher risk of malignancy in the lower and similarly upper thyroid poles. Besides well-defined malignancy indicators in the literature and guidelines, localization information is promising for this purpose in the future.

The Risk of Thyroid Cancer in Patients with Thyroid Nodule 3 Cm Or Larger

OBJECTIVE

There are conflicting data on the risk of thyroid cancer in thyroid nodules 3 cm or larger, and few such studies on this issue have been conducted in Asia. This study aimed to examine the risk of thyroid cancer in patients with thyroid nodules 3 cm or larger.

METHODS

This was a 7-year retrospective study conducted in a tertiary referral hospital in Taiwan. All patients with a thyroid nodule measuring ≥3 cm who underwent thyroid operation with or without fine-needle aspiration biopsy (FNAB) were included. The prevalence rate of thyroid cancer, as well as the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and false-negative rate of FNAB for thyroid nodule ≥3 cm were also examined.

RESULTS

A total of 132 patients were included in this study. Thyroid cancer was detected in 19 of 132 (14.4%) thyroid nodules measuring ≥3 cm. The performance of FNAB for detecting cancer in nodules 3 cm or larger without considering other ultrasonography parameters was relatively poor with a sensitivity of 50%, but the specificity (100%), PPV (100 %), and NPV (93.4 %) were excellent.

CONCLUSION

The risk of thyroid cancer for thyroid nodules ≥3 cm in this study was low. The PPV and NPV of FNAB were high for the detection of cancer in large nodules. The decision to perform thyroidectomy should not be solely based on nodule size and should include other factors, such as ultrasound characteristics and surgical risk.

False-negative Results with the Bethesda System of Reporting Thyroid Cytopathology: Predictors of Malignancy in Thyroid Nodules Classified as Benign by Cytopathologic Evaluation

The benign category of the Bethesda System for reporting thyroid cytopathology (BSRTC) predicts an incidence of malignancy from zero to three per cent. However, recent series report higher rates of malignancy ranging from eight to 14 per cent. Surgery is often performed for reasons other than their fine needle aspiration biopsy (FNAB) such as symptoms, nodule enlargement, or worrisome imaging. We hypothesized that an analysis of patients who underwent thyroidectomy despite a benign FNAB would identify predictors of malignancy, an area not currently addressed by American Thyroid Association guidelines. We performed a retrospective analysis of patients with benign FNAB results who underwent thyroidectomy from October 2007 to October 2012. Data collected included symptoms, imaging findings, FNAB results, and operative and histopathology results, all of which were obtained by chart review. Findings were compared between patients with and without a diagnosis of malignancy. Statistical significance was set as P < 0.05. Of 3839 FNABs, 2838 were benign. Of these, 180 underwent surgery for indications other than the FNAB category. Twenty-four (13.4%) malignancies were identified: 12 (6.7%) incidental microcarcinomas and 12 (6.7%) significant cancers (papillary greater than 1.0 cm, any nonpapillary histology). No patient's symptoms or signs reached significance as a predictor of malignancy. Suspicious ultrasound appearance was significantly associated with an underlying carcinoma ( P = 0.004). The false-negative result with benign FNAB is higher in surgical series than suggested by the BSRTC. Patients with tolerable symptoms may be observed in the face of a benign FNAB. Additionally, despite a benign FNAB, recommendations for closer follow-up or surgical intervention are warranted if the ultrasound appearance is suspicious.

Is patient age associated with risk of malignancy in a ≥4 cm cytologically benign thyroid nodule?

BACKGROUND

Current data regarding the risk of malignancy in a large thyroid nodule with benign fine-needle aspiration biopsy(FNAB) is conflicting. We investigated the impact of patient age on the risk of malignancy in nodules≥4 cm with benign cytology.

METHODS

We performed a single-institution retrospective review of patients who underwent surgery from 07/2008-08/2019 for a cytologically benign thyroid nodule ≥4 cm. The relationship between malignant histopathology and patient and ultrasound features was assessed with multivariable logistic regression.

RESULTS

Of 474 nodules identified, 25(5.3%) were malignant on final pathology. In patients <55 years old, 21/273(7.7%) nodules were malignant, compared to 4/201(2.0%) in patients ≥55. Patient age ≥55 was independently associated with significantly lower risk of malignancy(OR:0.2,95%CI:0.1-0.7,p = 0.011). Increasing nodule size >4 cm and high-risk ultrasound features were not associated with risk of malignancy(OR:1.0,95%CI:0.7-1.4,p = 0.980, and OR:9.6,95%CI:0.9-107.8,p = 0.066, respectively).

CONCLUSIONS

Patients <55 years old are 3.7-fold more likely to have a falsely benign FNA biopsy in a nodule≥4 cm.

The relationship of thyroid nodule size on malignancy risk according to histological type of thyroid cancer

Background

Although several studies have examined the value of thyroid nodule size as a malignancy predictor, the results are conflicting.

Purpose

To investigate the relationship between nodule size and malignancy risk and to evaluate the impact of nodule size on the false-negative rate of fine needle aspiration or core needle biopsy according to the histological type of thyroid cancer.

Material and Methods

From January 2013 to December 2013, 3970 thyroid nodules that underwent ultrasound-guided fine needle aspiration or core needle biopsy were retrospectively reviewed. We assessed the relationship between nodule size and malignancy risk according to histological type of thyroid cancer. In addition, we compared the false-negative rate by thyroid nodule size category.

Results

Of 3970 thyroid nodules, 1170 nodules were malignant. For papillary thyroid carcinoma, nodule size was inversely related to malignancy risk, whereas in nodules of follicular carcinoma and follicular variant papillary thyroid carcinoma, nodule size was positively related to malignancy risk ( P < 0.001). The false-negative rate tended to increase as nodule size increased ( P = 0.002) for all nodules and the overall false-negative rate was 2.3%.

Conclusion

Overall, nodule size does not correlate with risk of malignancy, but the relationship between nodule size and malignancy risk depends on the histological type of thyroid cancer.

Causes of misdiagnoses by thyroid fine-needle aspiration cytology (FNAC): our experience and a systematic review

Objective

FNA is a simple, safe, cost-effective and accurate diagnostic tool for the initial screening of patients with thyroid nodules. The aims of this study were to determine the diagnostic utility of FNAC performed in our institution, assess the cytomorphologic features that contribute to diagnostic errors and propose improvement measures.

Methods

A total of 2781 FNACs were included in the study, and 1122 cases were compared with their histological diagnoses. We retrospectively reexamined our discordant (both false-negative and false-positive) cases and performed a systematic review of previous studies on causes of misdiagnoses.

Results

When DC V and DC VI were both considered cytologic-positive, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy were 98.3, 30.9, 94.9, 58.3 and 93.5%, respectively. If DC VI was considered cytologic-positive, the sensitivity, specificity, PPV, NPV and diagnostic accuracy of FNAC were 98.0, 84.0, 99.4, 58.3, and 97.5% respectively. The main cause of false-negative diagnoses was sampling error (13/15, 86.7%), while interpretation error led to the majority of the false-positive diagnoses (38/47, 80.9%). Overlapping cytological features in adenomatous hyperplasia, thyroiditis and cystic lesions were the major factors contributing to interpretation errors, while the size and number of nodules may have led to false-negative diagnoses because of heterogeneity and unsampled areas.

Conclusions

The sensitivity and PPV of thyroid FNAC in our institution were higher than those in the published data, while the specificity and NPV were lower. Regarding the FNA category DC V, a frozen section analysis during diagnostic lobectomy is necessary. Multiple passes should be performed in various parts of a large nodule or from different nodules to reduce the risk of false-negative findings. Cytopathologists should strengthen their criteria for the identification of adenomatous hyperplasia, thyroiditis and cystic lesions to avoid false-positive diagnoses. NIFTP has little effect on diagnostic accuracy and the distribution of diagnostic errors.

Association between thyroid nodule size and malignancy rate

INTRODUCTION

The diagnostic performance of ultrasound-fine needle aspiration to identify thyroid nodules harbouring malignancy remains variable. The aim of this study was to determine thyroid nodule size and cytological classification as predictors of malignancy risk.

MATERIALS AND METHODS

We conducted a retrospective cohort analysis at an academic hospital involving 499 consecutive patients who underwent thyroid surgery between 2004 and 2015.

RESULTS

A total of 503 thyroid nodules (499 patients, 84% female; mean age 50.8 years, standard deviation, SD, 15.4 years) were analysed. Of these, 19.5% were malignant. The mean (± SD) nodule size was 3.28 ± 1.63 cm and 3.27 ± 1.54 cm for benign and malignant nodules, respectively. The odds of malignancy for thyroid nodules less than 3.0 cm was similar to those for nodules of 3.0 cm or greater (0.26 compared with 0.29; p=0.77). Overall, the sensitivity and specificity of fine-needle aspiration in this cohort were 71.4% and 100%, respectively. The overall false negative rate was 5.4%. When the cut-off of 3.0 cm was used, the false negative rate in thyroid nodules less than 3.0 cm was 0% compared with 7.0% in nodules of 3.0 cm or greater. Thus, class (p<0.01) but not nodule size (p=0.49), was associated with higher malignancy risk.

CONCLUSIONS

Our results suggest that thyroid nodule size did not accurately predict the risk of thyroid malignancy irrespective of fine-needle aspiration cytology. Routine diagnostic thyroid lobectomy solely owing to thyroid nodule size of 3.0 cm or greater is currently not justified.

Predictors for malignancy risk in subcentimeter thyroid nodules categorized as atypia/follicular lesion of undetermined significance by fine needle aspiration

Little work has been done on the prediction of malignancy risk in patients with subcentimeter thyroid nodule (TN) categorized as atypia/follicular lesion of undetermined significance (AUS/FLUS). We performed a retrospective analysis on the medical records of subcentimeter TNs whose initial fine-needle aspiration (FNA) diagnosis was AUS/FLUS at our center between November 2013 and August 2018. Univariate analysis and multivariate logistic regression analysis were used to select independent factors associated with malignancy. Of the 324 patients who were classified as AUS/FLUS on initial FNA, 153 patients underwent surgical procedures and showed an associated malignancy rate of 45.10% (69/153). The malignancy rates in AUS/FLUS settings with and without repeat FNA were 38.30% (18/47), and 48.11% (51/106), respectively, p = 0.260. Multivariate logistic regression analysis revealed that age < 55 (OR 3.015, 95% CI 1.196-7.596), microcalcification (OR 9.162, 95% CI 3.332-25.916) and taller than wide shape (OR 10.785, 95% CI 4.108-28.319) were three independent predictors for malignancy. The malignancy rates in the patients with one or none of predictor and patients with two or three above predictors were 20.5% (17/83) and 74.3% (52/70), respectively, p < 0.001 (OR 11.216, 95% CI 5.266-23.885). In conclusion, our study showed that for subcentimeter TNs with AUS/FLUS category, patient's age, taller than wide shape and microcalcification were three independent predictive factors for malignancy, which was helpful for decision-making of surgery or observation in such patient population.

Treatment of solitary thyroid nodules according to size, preoperative fine-needle aspiration cytology and frozen section: a retrospective single centre study

Background: In order to avoid unnecessary thyroidectomies, it is important to predict the nature of thyroid nodules the more accurately possible. The size of the nodule as a predictive factor for malignancy is very controversial. Another point of debate is the accuracy of preoperative fine-needle aspiration cytology (FNAC) and frozen section (FS). The aim of our study is to correlate the nodule size with the final histological diagnosis and to estimate the accuracy of preoperative FNAC and FS. Methods: Retrospective study including 387 operated patients with ultrasound-detected solitary thyroid nodules from 01 January 2001 to 31 December 2013. The following data were collected: patient age and sex, nodule size, FNAC, FS and final histology results. Results: The odds ratio for malignancy within nodules <40 mm was 2.12 (95% CI: 1.104-4.084). The specificity of FNAC was 97.78% and the negative predictive value (NPV) was 97.78% for nodules ≥40 mm and 93.2% and 96.5% for nodules <40 mm, respectively. The observed specificity and NPV of FS ranged from 98% to 100% and from 87.4% to 98%, respectively. When combining FNAC and FS, the specificity and the NPV were 99% and 98%, respectively. Conclusions: The nodule size is not a predictive factor for thyroid cancer and therefore nodules ≥40 mm should not be routinely resected. A lege artis preparation and performance of FNAC along with an expertise on cytological interpretation can considerably diminish false-negative rate. FS can offer additional accuracy on FNAC results and should, therefore, be a part of patient treatment.

The influence of thyroid nodule size on the diagnostic efficacy and accuracy of ultrasound guided fine-needle aspiration cytology

BACKGROUND

Diagnostic accuracy of fine-needle aspiration cytology (FNAC) in large and subcentimeter nodules is still debated. We aimed to evaluate the impact of nodule size on efficacy of the ultrasound-guided FNAC.

METHODS

B-mode grayscale ultrasound (US), US-guided FNAC according to Bethesda system and histopathological data of 514 nodules from 371 patients, who underwent thyroidectomy were examined retrospectively. Nodules were grouped by maximal diameter; group A nodules were smaller than 10 mm (n = 59), group B nodules were between 10 and 29 mm (n = 218), and group C nodules were 30 mm or greater (n = 130).

RESULTS

Sensitivity, specificity, and accuracy of FNAC was 92.0%, 100%, and 95.1% in group A, 80.7%, 99.1%, and %92.9 in group B, 70.0%, 98.9%, and 95.8% in group C nodules, respectively. The prevalence of papillary thyroid cancer (PTC) and incidental PTC were 44.2% (n = 164) and 6.4% (n = 24), respectively. Malignancy rate was more frequent in group A when compared to groups B and C (P < 0.01). Nodule size was positively associated with follicular cancer risk (P = 0.009). The thyroid stimulating hormone level was positively associated with malignancy (P = 0.02) and optimal cut-off value was 0.96 mIU/L. False-negative rate was 8.0%, 19.3%, and 30.0% in groups A, B, and C nodules, respectively.

CONCLUSIONS

Although the malignancy rate was low in nodules ≥30 mm, diagnostic surgery for large nodules should be considered because of decreased reliability of FNAC, ineffectiveness of clinical and sonographic criteria. False-negative rate was relatively low and malignancy rate was high in subcentimeter nodules, supporting the accuracy of FNAC.

Large Cytologically Benign Thyroid Nodules Do Not Have High Rates of Malignancy or False-Negative Rates and Clinical Observation Should be Considered: A Meta-Analysis

Background: Management of large thyroid nodules is controversial, as data are conflicting regarding overall rates of malignancy (ROM) in all nodules and frequency of false-negative fine-needle aspiration results (FNR) in cytologically benign nodules. This meta-analysis aimed to evaluate and compare ROM and FNR in small versus large nodules published in the literature. Methods: Articles indexed in PubMed, written in English, published electronically or in print on or prior to December 8 2017 were searched for "false negative thyroid size or cm" and "malignancy rates benign thyroid nodules." Three hundred fifty-two unique citations were identified. Multiple reviewers selected a final set of 35 articles that contained nodules stratified by size (3, 4, or 5 cm), with benign or all cytologic diagnoses, and with postsurgical histologic diagnoses. Multiple observers extracted data, including numbers of total, cytologically benign, and histologically malignant nodules. Size cutoffs of 3, 4, and/or 5 cm were analyzed in 14, 24, and 1 article, respectively. Results: ROM in all nodules ≥3 cm (13.1%) and ≥4 cm (20.9%) was lower than those <3 cm (19.6%) and <4 cm (19.9%; odds ratio [OR] = 0.72 [confidence interval (CI) 0.64-0.81] and OR = 0.85 [CI 0.77-0.95]). FNR in nodules ≥3 cm (7.2%) was not different from smaller nodules (5.7%; OR = 1.47 [CI 0.80-2.69]). FNR in nodules ≥4 cm (6.7%) was slightly higher than those <4 cm (4.5%; OR = 1.38 [CI 1.06-1.80]). The most frequently reported false-negative diagnosis was papillary thyroid carcinoma. Conclusions: Rates of malignancy and false-negative FNA results vary but, in most studies, are not higher in larger nodules. Patients with large, cytologically benign thyroid nodules need not undergo immediate surgical resection, as false-negative FNA rates are low and are expected to decrease in light of nomenclature revision of a subset of follicular variants of papillary thyroid carcinoma.

Thyroid nodule size calculated using ultrasound and gross pathology as predictors of cancer: A 23-year retrospective study

BACKGROUND

Thyroid nodules are very common. Ultrasound (US) and fine needle aspiration (FNA) are both integral in cancer screening. This study investigated the concordance between thyroid nodule sizes measured by US and gross pathologic examination and their relationship with malignancy.

METHODS

A retrospective design was used to select consecutive patients with proven carcinoma of the thyroid. The number and maximum diameter of nodules, rates and types of malignancy, as well as predictors of malignancy were determined.

RESULTS

The 10 944 patients examined had 15 283 thyroid nodules, 44.6% of which were malignant. Of the 4449 nodules sampled by FNA and the 8748 not sampled by FNA, 76.5% and 30.5% were malignant, respectively. The sensitivity, specificity, positive and negative predictive values (NPVs), and overall accuracy of FNA based on final pathology were 97.9%, 96.3%, 98.8%, 93.5%, and 97.5%, respectively. Nodule sizes determined by US were comparable with most nodules having either the same size range (n = 2959, 77.7%) or differing only by one size range (n = 770, 20.5%).

CONCLUSIONS

Thyroid nodule size is inversely related to malignancy risk, as larger nodules have lower malignancy rates. Nodule size estimated by US shows relatively good correlation with final pathologic size. However, thyroid nodules should undergo FNA regardless of size. If the FNA is not benign, nodule size should influence therapeutic decision making.

The Value of Negative Diagnosis in Thyroid Fine-Needle Aspiration: a Retrospective Study with Histologic Follow-Up

The Bethesda System for reporting thyroid cytopathology (BSRTC) predicts an incidence of malignancy of less than 5% in thyroid nodules with a benign diagnosis on fine-needle aspiration (FNA). However, recent series have suggested that the true rate of malignancy might be significantly higher in this category of patients. We reviewed our experience by performing a retrospective analysis of patients with benign thyroid FNA results who underwent thyroidectomy between 2008 and 2013 at a large academic center. Information including demographics, ultrasound features, FNA diagnosis, and surgical follow-up information were recorded. Slides were reviewed on cytology-histology discrepant cases, and it was determined whether the discrepancy was due to sampling or interpretation error. A total of 802 FNA cases with a benign diagnosis and surgical follow-up were identified. FNA diagnoses included 738 cases of benign goiter and 64 cases of lymphocytic thyroiditis. On subsequent surgical resection, 144 cases were found to be neoplastic, including 117 malignant cases. False negative, defined as interpretation error and inadequate biopsy of the nodule harboring malignancy, was 6%. When cases of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) were excluded from the analysis, false-negative rate was 5%. When microPTC cases were excluded, false-negative rate was 3% and was slightly less than 3% when both microPTC and NIFTP cases were excluded from the analysis. Retrospective review of neoplastic cases showed that 57% were due to sampling error and 43% were due to interpretation error. Interpretation error was more likely to occur in follicular patterned neoplasms (75%), while sampling error was more common in non-follicular variants of papillary thyroid carcinoma (non-FVPTC) (61%). With the exclusion of microPTC, interpretation errors were still more likely to occur in follicular neoplasms (79%) but there was no significant difference in sampling error between non-FVPTC (37%) and follicular patterned neoplasms (42%). Tumor size was larger in cases with interpretation error (mean = 2.3 cm) compared to cases with sampling error (mean = 1.4 cm). This study shows that the false-negative rate of thyroid FNA at our institution is not significantly above the rate suggested by the BSRTC. Interpretation errors were more likely to occur in follicular patterned neoplasms, while non-FVPTC was more frequently found in false negative cases due to inadequate sampling.

Size and Ultrasound Features Affecting Results of Ultrasound-Guided Fine-Needle Aspiration of Thyroid Nodules

OBJECTIVES

Our goal was to assess the diagnostic efficacy of ultrasound (US)-guided fine-needle aspiration (FNA) of thyroid nodules according to size and US features.

METHODS

A retrospective correlation was made with 1745 whole thyroidectomy and hemithyroidectomy specimens with preoperative US-guided FNA results. All cases were divided into 5 groups according to nodule size (≤5, 5.1-10, 10.1-15, 15.1-20, and >20 mm). For target nodules, static images and cine clips of conventional US and color Doppler were obtained. Ultrasound images were reviewed and evaluated by two radiologists with at least 5 years US working experience without knowing the results of pathology, and then agreement was achieved.

RESULTS

The Bethesda category I rate was higher in nodules larger than 15 mm (P < .05). The diagnostic accuracy was best in nodules of 5 to 10 mm in diameter. The sensitivity, accuracy, PPV, and LR for negative US-guided FNA results were better in nodules with a size range of 5 to 15 mm. The specificity, negative predictive value (NPV), and LR for positive results and the Youden index rose with increasing nodule size. Seventeen false-positive and 60 false-negative results were found in this study. The false-negative rate rose with increasing nodule size. However, the false-positive rate was highest in the group containing the smallest nodules. Nodules with circumscribed margins and those that were nonsolid and nonhypoechoic and had no microcalcifications correlated with Bethesda I FNA results. Nodules with circumscribed margins and those that were nonsolid, heterogeneous, and nonhypoechoic and had increased vascularity correlated with false-negative FNA results. Borders correlated with Bethesda I false-negative and false-positive FNA results.

CONCLUSIONS

Tiny nodules (≤5 mm) with obscure borders tended to yield false-positive FNA results. Large nodules (>20 mm) with several US features tended to yield false-negative FNA results.

Impact of Nodule Size on Malignancy Risk Differs according to the Ultrasonography Pattern of Thyroid Nodules

Objective

To test whether the impact of thyroid-nodule size on the malignancy risk differs according to the ultrasonography (US) patterns of nodules.

Materials and Methods

This study is a post hoc analysis using data from the Thyroid Imaging Reporting and Data System (TIRADS) multicenter retrospective study which included 2000 consecutive thyroid nodules (≥ 1 cm) with final diagnoses. A total of 2000 consecutive thyroid nodules from 1802 patients (1387 women and 613 men; mean age, 51.2 ± 12.2 years) were enrolled in this study. The malignancy risk of the nodules was assessed according to the nodule size and US patterns (Korean-TIRADS).

Results

Overall, the malignancy risk did not increase as nodules enlarged. In high-suspicion nodules, the malignancy rate had no association with nodule size (p = 0.467), whereas in intermediate- or low-suspicion nodules there was a trend toward an increasing malignancy risk as the nodule size increased (p = 0.004 and 0.002, respectively). The malignancy rate of large nodules (≥ 3 cm) was higher than that of small nodules (< 3 cm) in intermediate-suspicion nodules (40.3% vs. 22.6%, respectively; p = 0.001) and low-suspicion nodules (11.3% vs. 7.0%, respectively; p = 0.035). There was a trend toward a decreasing risk and proportion of papillary carcinoma and an increasing risk and proportion of follicular carcinoma or other malignant tumors as nodule size increased (p < 0.001, respectively).

Conclusion

The impact of nodule size on the malignancy risk differed according to the US pattern. A large nodule size (≥ 3 cm) showed a higher malignancy risk than smaller nodules in intermediate- and low-suspicion nodules.

Validation of the 2015 American Thyroid Association Management Guidelines for Thyroid Nodules With Benign Cytologic Findings in the Era of the Bethesda System

OBJECTIVE

The purpose of this study is to investigate follow-up strategies for cytologically benign thyroid nodules according to size and ultrasound (US) pattern according to the 2015 American Thyroid Association (ATA) guidelines in the era of the Bethesda system.

MATERIALS AND METHODS

This retrospective study included 1208 patients with 1230 nodules that were cytologically benign at initial fine-needle aspiration performed from June 2012 to December 2014. False-negative rates (FNRs) were calculated by considering nodule size and US pattern according to the 2015 ATA guidelines and were compared between nodules with the high-suspicion US pattern and nodules with the high- or intermediate-suspicion US patterns according to size.

RESULTS

Twenty-five of the 1230 nodules (2.0%) were malignant. The FNRs were 5.1% (8/158) for nodules with the high-suspicion US pattern and 1.6% (17/1072) for nodules with other US patterns. With regard to nodule size, the FNRs were 3.2% (9/277) for nodules 3 cm or larger and 5.2% (6/115) for nodules 4 cm or larger. The FNRs of nodules with the high-suspicion pattern were not significantly higher than those of nodules with the high- or intermediate-suspicion patterns among nodules 2 cm or larger (2.5% vs 1.9%; p = 0.208), 3 cm or larger (3.4% vs 2.9%; p = 0.498), and 4 cm or larger (5.4% vs 3.8%; p = 0.353).

CONCLUSION

Thyroid nodules with initial benign cytologic findings had a low malignancy rate in the era of the Bethesda system, regardless of US pattern and size. Therefore, any immediate diagnostic intervention may be discouraged in cytologically benign nodules.

Large (≥3cm) thyroid nodules with benign cytology: Can Thyroid Imaging Reporting and Data System (TIRADS) help predict false-negative cytology?

Background

There is controversy about the accuracy of the fine-needle aspiration (FNA) cytology results in large sized thyroid nodules. Our aim was to evaluate the false-negative rate of FNA for large thyroid nodules and the usefulness of the Thyroid Imaging Reporting and Data System (TIRADS) in predicting false-negative cytology for large thyroid nodules with benign cytology.

Methods

632 thyroid nodules larger than or equal to 3cm in size with subsequent benign cytology on US-guided FNA were included. US features of internal composition, echogenicity, margin, calcifications, and shape were evaluated, and nodules were classified according to TIRADS. TIRADS category 3 included nodules without any of the following suspicious features:solidity, hypoechogenicity or marked hypoechogenicity, microlobulated or irregular margins, microcalcifications, and taller-than-wide shape. Category 4a, 4b, 4c, and 5 were assigned to nodules showing one, two, three or four, or five suspicious US features, respectively. US features associated with malignancy for these lesions were analyzed and malignancy risk according to TIRADS was calculated.

Results

Of the 632 lesions, 23 lesions(3.6%) were malignant and 609(96.4%) were benign, suggesting a 3.6% false-negative rate for FNA cytology. Of the 23 malignant lesions, final pathology was mainly follicular carcinoma minimally invasive(65.2%, 15/23) and the follicular variant of papillary carcinoma(26.1%, 6/23). The malignancy risks of categories 3, 4a, 4b, and 4c nodules were 0.9%, 4.6%, 10.0%, and 11.8%, respectively.

Conclusion

Large thyroid nodules with benign cytology had a relatively high false-negative risk of 3.6% and TIRADS was helpful in predicting false-negative cytology for these lesions.

Underestimated risk of cancer in solitary thyroid nodules ≥3 cm reported as benign

BACKGROUND

The study aims to assess the risk of cancer in solitary thyroid nodules ≥30 mm in size reported as Bethesda II, and its implications.

METHOD

The clinical records of 202 patients, who underwent thyroid lobectomy for solitary nodules measuring ≥30 mm, reported as Bethesda II on preoperative FNAC between Jan 2015 and Apr 2016 were reviewed. Data collected included nodule size and consistency, and final histopathology results. The risk of cancer and the recommended management according to ATA guidelines were the outcomes of interest. Comparisons were then made between two size categories: (30-40 mm; n = 72; C1) and (>40 mm; n = 130; C2), and two nodule consistencies.

RESULTS

Mean nodule size was 43.2 mm (range 30-92). Ninety-five percent were solid and 5% were predominantly cystic. The risk of cancer was 22.8% (46/202) with no size threshold, or graded increase in risk observed. Based on biologic behavior, 50% of cancers were considered clinically significant. Accordingly, the risk of cancer for which surgery is recommended was 11.4% (23/202). The risk of cancer requiring total thyroidectomy was 9.4% and was influenced by nodule size (19 vs. 60% in C1 and C2, respectively; p = 0.01). Predominantly cystic nodules had a greater risk of malignancy compared to predominantly solid nodules even after adjusting for size (40 vs. 9.9%; p = 0.01 and 40 vs. 12.5%; p = 0.02, respectively).

CONCLUSION

The risk of malignancy in Bethesda II solitary nodules ≥30 mm is considerable implying a need for changing the way these are approached and refining cytopathology reporting.

Thyroid Nodule Size at Ultrasound as a Predictor of Malignancy and Final Pathologic Size

BACKGROUND

Thyroid-related mortality has remained constant despite the increasing incidence of thyroid carcinoma. Most thyroid nodules are benign; therefore, ultrasound and fine needle aspiration (FNA) are integral in cancer screening. We hypothesize that increased nodule size at ultrasound does not predict malignancy and correlation between nodule size at ultrasound and pathologic exam is good.

METHODS

Resected thyroids with preoperative ultrasounds were identified. Nodule size at ultrasound, FNA diagnosis by Bethesda category, size at pathologic examination, and final histologic diagnosis were recorded. Nodule characteristics at ultrasound and FNA diagnoses were correlated with gross characteristics and histologic diagnoses. Nodules for which correlation could not be established were excluded.

RESULTS

Of 1003 nodules from 659 patients, 26% were malignant. Nodules <2 cm had the highest malignancy rate (∼30%). Risk was similar (∼20%) for nodules ≥2 cm. Of the 548 subject to FNA, 38% were malignant. Decreasing malignancy rates were observed with increasing size (57% for nodules <1 cm to 20% for nodules >6 cm). At ultrasound size cutoffs of 2, 3, 4, and 5 cm, smaller nodules had higher malignancy rates than larger nodules. Of the 455 not subject to FNA, 11% were malignant. Ultrasound size alone is a poor predictor of malignancy, but a relatively good predictor of final pathologic size (R² = 0.748), with less correlation at larger sizes. In nodules subject to FNA, false negative diagnoses were highest (6-8%) in nodules 3-6 cm, mostly due to encapsulated follicular variant of papillary carcinoma.

CONCLUSIONS

Thyroid nodule size is inversely related to malignancy risk, as larger nodules have lower malignancy rates. However, the relationship of size to malignancy varies by FNA status. All nodules (regardless of FNA status) demonstrate a risk trough at ≥2 cm. Nodules subject to FNA show step-wise decline in malignancy rates by size, demonstrating that size alone should not be considered as an independent risk factor. Size at ultrasound shows relatively good correlation with final pathologic size. False negative rates are low in this series. Lesions with the appropriate constellation of clinical and radiographic findings should undergo FNA regardless of size. Both size and FNA diagnosis should influence the clinical decision-making process.

The impact of presence of Hashimoto's thyroiditis on diagnostic accuracy of ultrasound-guided fine-needle aspiration biopsy in subcentimeter thyroid nodules: A retrospective study from FUSCC

The incidence of PTMC has been increasing in the recent years. This study aimed to investigate the diagnostic value of US-FNA in thyroid nodules ≤1 cm and whether the presence of Hashimoto's thyroiditis (HT) in thyroid could influence the accuracy. The patients who accepted US-FNA at FUSCC from December 2012 to November 2015 and followed our criteria were enrolled in this study. We extracted the cytological, pathological, and follow-up US/US-FNA data of patients with subcentimeter nodules. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), false-negative rate (FNR), false-positive rate (FPR), and AUC were calculated to define FNA diagnostic performance in patients. The association of HT with cytological results was analyzed in univariate and multivariate logistic regression analysis. In total, 754 patients with 817 subcentimeter nodules were collected to comprise the FUSCC cohort. Of the 817 nodules, the cytological results were ND/UNS in 80 nodules (9.8%), benign in 74 (9.1%), AUS/FLUS in 80 (9.8%), FN/SFN in 6 (0.7%), suspicious for malignancy (SM) in 222 (27.2%), and malignant in 355 (43.5%). The sensitivity, specificity, PPV, NPV, and AUC of US-FNA for the subcentimeter nodules were 98.8%, 90.5%, 98.8%, 90.5%, and 94.7%, respectively. In comparison with HT-positive subcentimeter nodules, the diagnostic value of US-FNA for HT-negative nodules was significantly higher (HT-positive: AUC = 91.6%, HT-negative: AUC = 95.9%, P = 0.028). The coexistent HT was found to increase the risk of the FNR and indeterminate cytological results. US-FNA demonstrated an effective method for diagnosis of subcentimeter thyroid nodules with a low nondiagnostic rate in our study. The presence of HT in thyroid could be a risk factor for the increased FNR and indeterminate cytological results during US-FNA.

Effects of nodule characteristics on sampling number and duration of thyroid fine-needle aspiration biopsy: size does not matter, but cystic degeneration ratio does

Background Ultrasound-guided fine needle aspiration biopsy (FNAB) of thyroid nodules, though the most accurate method to rule out malignancy, still has an inherent risk of yielding non-diagnostic specimens despite immediate assessment of specimen adequacy by an on-site cytopathologist. Purpose To evaluate the effects of nodule volume and extent of cystic degeneration on total biopsy time and number of aspirations required for obtaining an adequate specimen. Material and Methods A total of 510 patients underwent FNAB by a single radiologist accompanied by a cytopathologist who immediately assessed each sample for specimen adequacy. All sampled nodules were single and had one maximum diameter > 10 mm. Nodule volumes and cystic degeneration ratios were calculated prior to the intervention. Aspirations were repeated until the cytological material was deemed adequate by the cytopathologist; the number of aspirations and total biopsy time were then recorded. Results Nodule volumes did not have significant effect on neither number of aspirations necessary for achieving specimen adequacy ( P > 0.05) nor total biopsy time (r = -0.148 with P = 0.001). Predominantly cystic nodules, compared to predominantly solid nodules, required more sampling per nodule (4.58 ± 1.11 vs. 3.44 ± 1.19 aspirations, P = 0.001) and longer total biopsy time (16.40 ± 6.19 vs. 11.15 ± 6.18 min, P = 0.001). Conclusion Predominantly cystic nodules require allocation of more time for biopsy. To ensure specimen adequacy when immediate specimen evaluation by an on-site cytopathologist is not possible, four samples from predominantly solid nodules and five passes through predominantly cystic nodules are required.

Reliability of fine needle aspiration biopsy in large thyroid nodules

OBJECTIVE

Fine needle aspiration biopsy provides one of the most important data that determines the treatment algorithm of thyroid nodules. Nevertheless, the reliability of fine needle aspiration biopsy is controversial in large nodules. The aim of this study was to evaluate the adequacy of fine needle aspiration biopsy in thyroid nodules that are four cm or greater.

MATERIAL AND METHODS

We retrospectively examined 219 patients files who underwent thyroidectomy for thyroid nodules that were greater than four centimeter between May 2007 and December 2012. Seventy-four patients with hyperthyroidism, and 18 patients without preoperative fine needle aspiration cytology were excluded from the study. Histopathologic results after thyroidectomy were compared with preoperative cytology results, and sensitivity and specificity rates were calculated.

RESULTS

False-negativity, sensitivity and specificity rates of fine needle aspiration biopsy of thyroid nodules were found to be 9.7%, 55.5%, and 85%, respectively. Within any nodule of the 127 patients, 28 (22.0%) had thyroid cancer. However, when only nodules of at least 4 cm were evaluated, thyroid cancer was detected in 22 (17.3%) patients.

CONCLUSION

In this study, fine needle aspiration biopsy of large thyroid nodules was found to have a high false-negativity rate. The limitations of fine-needle aspiration biopsy should be taken into consideration in treatment planning of thyroid nodules larger than four centimeters.

Clinical Factors Influencing the Performance of Gene Expression Classifier Testing in Indeterminate Thyroid Nodules

BACKGROUND

Molecular diagnostic testing is increasingly used in the management of indeterminate thyroid nodules. Limited data exist regarding the influence of clinical factors on gene expression classifier (GEC) test performance. This study examined the positive and negative predictive value of GEC as stratified by nodule size.

METHODS

A prospectively maintained pathology database from a single tertiary referral center was queried from 2012 to 2015 for indeterminate thyroid nodules that underwent GEC testing. Nodule size, patient demographics, Bethesda classification, and Hürthle cell-predominant nodules (HCNs) were evaluated as predictors of GEC performance.

RESULTS

Two hundred and thirty-one patients with 245 indeterminate nodules were examined. Assuming all nodules to be benign unless proven malignant on histopathology, the sensitivity and specificity of GEC testing were 95.2% and 60.1%, respectively. The malignancy rate among resected nodules was 25.3%. The positive predictive value was consistent across nodule sizes: 45.5% for nodules <1 cm, 42.9% for nodules 1-1.9 cm, 36.0% for nodules 2-2.9 cm, 54.2% for nodules 3-3.9 cm, and 50.0% for nodules ≥4 cm. The negative predictive value ranged from 93.3% to 100% and was not affected by nodule size. HCNs had a high rate of GEC suspicious results (77.4% vs. 50.5% for nodules without Hürthle cell predominance, p < 0.01), though this did not correspond to a difference in the rate of malignancy (25.8% vs. 25.3%).

CONCLUSIONS

Nodule size did not affect GEC test performance in the present cohort. GEC benign results remain reliable in large nodules. GEC suspicious nodules >3 cm carry a similar risk of malignancy compared to smaller nodules, and do not warrant more aggressive treatment. GEC testing has limited clinical utility for HCNs due to the high rate of false-positive results.

Value of fine-needle aspiration in evaluating large thyroid nodules

BACKGROUND

The American Thyroid Association (ATA) recommends using ultrasound-guided fine-needle aspiration (FNA) in order to evaluate supracentimetric and suspect thyroid nodules. The purpose of this study was to evaluate the effective use of FNA before surgery for nodules over 3 cm in diameter.

METHODS

In this retrospective study, we analyzed the results of ultrasound-guided FNA and postoperative histological analysis in 843 nodules >3 cm.

RESULTS

The FNA was informative in 42.6%. The correlation with the final histological analysis was 94.8% for benign nodules and 71.0% for malignant nodules. The FNA had a positive predictive value of 71%, a specificity of 97%, a sensitivity of 56%, and a 4.7% rate of false-negative results.

CONCLUSION

Because there is a nonnegligible FNA risk of error, notably allowing the evolution of a cancer in 1 of 20 cases, the FNA data should not delay surgical intervention for potentially suspect nodules >3 cm in diameter. © 2016 Wiley Periodicals, Inc. Head Neck 39: 32-36, 2017.

Malignancy risk and false-negative rate of fine needle aspiration cytology in thyroid nodules ≥4.0 cm

BACKGROUND

We aimed to evaluate malignancy rate and to determine false negativity of fine needle aspiration biopsy (FNAB) in thyroid nodules ≥4.0 cm.

METHODS

The medical records of patients who underwent thyroidectomy between January 2007 and December 2014 were reviewed. Demographic and clinical data as well as preoperative ultrasonography findings were analyzed. The nodules in these patients were grouped as ≥4.0 cm and <4.0 cm according to ultrasonography measurements. Nodules <4.0 cm were further divided into 1.0-3.9 cm and <1.0 cm. Histopathologically malignant nodules with preoperative benign cytology were defined as having false-negative FNAB.

RESULTS

There were 1,008 nodules that measured ≥4.0 cm, 4,013 nodules that measured 1.0-3.9 cm, and 540 that measured nodules <1.0 cm. Based on histopathologic findings, 8.5%, 10.2%, and 25.6% of nodules ≥4.0 cm, 1.0-3.9 cm, and <1.0 cm were malignant, respectively (P < .001). There was no significant difference between 1.0-3.9-cm and ≥4.0-cm nodules with respect to malignancy (P = .108). False-negativity rates were 4.7% in nodules ≥4.0 cm, 2.2% in nodules measuring 1.0-3.9 cm, and 4.8% in <1.0-cm nodules. Nodules measuring <1.0 cm and ≥4.0 cm had similar false-negativity rates (P = .93), while 1.0-3.9-cm nodules had statistically lower false-negativity rates than those found in the other two groups (P = .03 and P < .001, respectively).

CONCLUSION

Of the nodules that were operatively excised, nodules ≥4.0 cm had a similar risk of malignancy as nodules 1.0-3.9 cm. The rate of false-negative FNAB in nodules ≥4.0 cm was twice as high as in nodules 1.0-3.9 cm; however, we do not think it is high enough to recommend a routine operation when cytology results are benign.

The McGill Thyroid Nodule Score's (MTNS+) role in the investigation of thyroid nodules with benign ultrasound guided fine needle aspiration biopsies: a retrospective review

Background

Ultrasound guided fine needle aspiration (USFNA) biopsies of thyroid nodules sometimes create a decision-making dilemma for surgeons as they may yield falsely benign results. The McGill Thyroid Nodule Score + (MTNS+) was developed to aid in clinical guidance regarding the management of patients with these USFNA results. The aim of this study was to assess the MTNS+ as a clinical tool in patients with benign preoperative thyroid nodule USFNAs and to analyze the relationship between nodule size and malignancy in these patients.

Methods

We conducted a retrospective chart review of 1312 patients who underwent thyroidectomies between 2010 and 2015 at the McGill University Teaching Hospitals. Patients with Bethesda II (benign) USFNA results, calculated MTNS+, and nodule size evaluated on ultrasound were included in the study. The false-negative rate was calculated, and MTNS+ and nodule size were each compared to final pathology results. Binary logistic regression was used for statistical analysis.

Results

Of the 1312 patients, 101 met the inclusion criteria and together had an average MTNS+ score of 6.83, which corresponds to a predicted malignancy rate between 25 and 33 %. Final pathology revealed malignancy in 16 (15.8 %) subjects. The average MTNS+ of patients with malignant nodules on surgical pathology was 8.25, while that of patients with benign nodules was 6.56.

Patients with nodule size 1–1.9 cm (a) and 2–2.9 cm (b) each had an equal rate of malignancy of 2.97 % (n = 3), nodule size 3–3.9 cm (c) had a rate of 1.98 % (n = 2), and nodule size ≥4 cm (d) a rate of 7.92 % (n = 8).

Conclusion

The rate of malignancy (15.8 %) is higher than expected when reviewing the risk of malignancy in nodules considered as Bethesda class 2. On the other hand, the rate is lower than the 25–33 % predicted by the MTNS+. We also found a higher malignancy rate for nodules above 4 cm in size, but size was a poor predictor of malignancy when used alone. Therefore, while the MTNS+ may be helpful at helping to identify USFNAs that are incorrectly classified as benign, the percentage risk of malignancy is lower than expected.

DO ALL THYROID NODULES >4 CM NEED TO BE REMOVED? AN EVALUATION OF THYROID FINE-NEEDLE ASPIRATION BIOPSY IN LARGE THYROID NODULES

OBJECTIVE

Controversy exists regarding the ability of fine-needle aspiration (FNA) biopsy to rule out malignancy when thyroid nodules exceed 4 cm in diameter. The goal of this study was to provide data regarding FNA accuracy in a clinical setting for detecting/ruling out malignancy in large thyroid nodules (≥4 cm) and discuss FNA utility in guiding surgical decisions.

METHODS

All thyroid FNA cases performed at Marshfield Clinic from 1/1/2000 to 12/31/2010 followed by complete or partial thyroidectomy on nodules of at least 4 cm were identified. Demographics, medical history, nodule biopsy characteristics, surgical procedures, and diagnosis data were abstracted. FNA was compared to histologic evaluation of surgical specimens.

RESULTS

A total of 198 patients with large thyroid nodules were identified. Most had a single large nodule, but ~40% were multinodular, and 206 total nodules were assessed. Females outnumbered males, and the mean age was ~50 years. After surgery, cancer was histologically identified in 49/206 (23.8%) nodules, including 9/123 nodules that had been categorized as benign by FNA, corresponding to a false-negative rate of 7.3%. Sensitivity/specificity for detecting malignancy by FNA was ~80%. The positive predictive value (PPV) was just below 60%, and the negative predictive value (NPV) was 93% but rose to 96% when papillary microcarcinomas were excluded.

CONCLUSION

While FNA sensitivity in large nodules was relatively low, NPV was high, especially if incidental papillary microcarcinomas were excluded. When cancer prevalence and NPV are known, FNA can be a reliable "rule out" test in nodules ≥4 cm. This information is critical and can help guide the surgery decision, especially in high-risk patients. The decision for surgery should not be solely based on nodule size but should consider additional factors including cancer prevalence, clinical history, ultrasound features, surgical risk, and life expectancy.

ABBREVIATIONS

FNA = fine-needle aspiration NPV = negative predictive value PPV = positive predictive value.

Does Tumor Size Influence the Diagnostic Accuracy of Ultrasound-Guided Fine-Needle Aspiration Cytology for Thyroid Nodules?

Background. Fine-needle aspiration cytology (FNAC) is diagnostic standard for thyroid nodules. However, the influence of size on FNAC accuracy remains unclear especially in too small or too large thyroid nodules. The objective of this retrospective cohort study was to investigate the effect of nodule size on FNAC accuracy. Methods. All consecutive patients who underwent thyroidectomy for nodules in 2010 were enrolled. FNAC results (according to the Bethesda system) were compared to pathological diagnosis. The nodules were categorized into groups A-E on the basis of maximal diameter on ultrasound (≤0.5, >0.5-1, >1-2, >2-4, and >4 cm, resp.). Results. There were 502 cases with 690 nodules. Overall FNAC sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 95.4%, 98.2%, 99.4%, 86.4%, and 96.0%, respectively. False-negative rates (FNRs) of groups A-E were 3.2%, 5.1%, 1.3%, 13.3%, and 50%, respectively. Accuracy rates of groups A-E were 96.8%, 94.8%, 99%, 94.7%, and 87.5%, respectively. Conclusion. Although accuracy rates of FNAC in thyroid nodules smaller than 0.5 cm are comparable to the other group, thyroid nodules larger than 4 cm with benign cytology carry a higher risk of malignancy, which suggest that those should be considered for intensive follow-up or repeated biopsy.

Fine-needle aspiration study of cystic papillary thyroid carcinoma: Rare cytological findings

Background:

Cystic papillary thyroid carcinoma (CPTC) is a variant of papillary carcinoma that has many mimickers in cytological grounds.

Aim:

To study the cytomorphologic features of CPTC and compare them to those of other cystic thyroid lesions using fine-needle aspiration cytology (FNAC). We also aimed to identify the cytomorphologic features that distinguish CPTC from other cystic thyroid lesions.

Materials and Methods:

Seventy-three cases of CPTC were included in the study. The cytomorphologic features of these cases were analyzed. The FNA smears of other thyroid lesions with cystic changes (300 colloid goiters, 290 adenomatoid nodules, 11 follicular neoplasms, and 9 hurtle cell neoplasm) were also studied.

Results:

The smears in CPTC revealed isolated follicular cells, small groups of cells with scalloped margins, cell swirls, small clusters with a cartwheel pattern, papillary clusters, intranuclear inclusions, nuclear grooves, sticky colloid, intracellular colloids, psammoma bodies, multinucleated giant cells, and foamy and hemosiderin laden macrophages. Small groups of cells with scalloped borders, cellular swirls, and small clusters with a cartwheel pattern were seen in CPTC, but not in other cystic lesions. Interestingly, mesothelial-like cells and hemophagocytic cells were seen in five and three cases of CPTC, respectively, but not in other cystic lesions.

Conclusion:

Mesothelial-like cells and hemophagocytic cells were observed in five and three cases of CPTC, respectively. Similar finding have not been previously reported in the literature.

An analysis of trends of incidence and cytohistological correlation of papillary carcinoma of the thyroid gland with evaluation of discordant cases

Background:

The role of fine-needle aspiration cytology (FNAC) in thyroid nodules has been well-studied but there is a paucity of studies solely involving papillary thyroid carcinoma (PTC). The diagnostic criteria for PTC are established but still there is a worrisome possibility of false positive and false-negative results, which can have a serious impact on patient care. This article correlates the cytological and histological diagnosis of PTC with an eventual aim of analyzing the cause of false positive and false negative results in order to prevent misdiagnosis. An increase in the incidence of PTC in the younger population has been noted.

Aims:

To analyze the epidemiological trends and cytohistological correlation of PTC and evaluate the discordant cases and pitfalls of FNAC.

Materials and Methods:

Seventy-two cases who had undergone both FNAC and histopathological examination (HPE) of the thyroid gland were selected. Age and sex distribution as well as cytohistological correlation were done for all the cases.

Results:

Cytohistological correlation was 81.94%. False positives were 5.56% and the false negative rate was 13.2%. Sensitivity was 86.7% and the positive predictive value was 93.6%. The peak age was 31-40 years among females and 41-60 years among males. Seven of our patients were <20 years of age (10%).

Conclusion:

FNAC is an indispensible tool for the early diagnosis of PTC. However, certain conditions of the thyroid gland can cause diagnostic dilemma. Awareness of pathologists regarding these pitfalls can prevent misdiagnosis and provide better patient care. Increasing the incidence of PTC with a more striking increase in the younger population makes early diagnosis all the more important owing to better prognosis in this age group.

Factors associated with the sensitivity of fine-needle aspiration cytology for the diagnosis of follicular variant papillary thyroid carcinoma

BACKGROUND

The purpose of this study was to evaluate the factors associated with diagnostic accuracy of preoperative fine-needle aspiration (FNA) for follicular variant papillary thyroid carcinoma (FVPTC).

METHODS

The patients with FVPTC who underwent thyroidectomy were divided into 2 groups: "group A" (Bethesda category II, III, or IV) versus "group B" (category V or VI).

RESULTS

A total of 225 patients (117 in group A and 108 in group B) were included. Group B was associated with older age, malignant ultrasonographic features, smaller tumor size, extrathyroidal extension, higher stage, and B-type Raf (BRAF)(V600E) mutation compared with group A. In multivariable analysis, malignant ultrasonographic features and tumor size ≤3.0 cm were independent predictive factors for group B.

CONCLUSION

FVPTCs >3.0 cm are unlikely to be diagnosed as category V or VI. Clinicians should keep FVPTC in mind and consider diagnostic lobectomy for the nodules regardless of FNA or ultrasonographic findings. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1467-E1471, 2016.

Thyroid fine needle aspiration biopsy: do nodule volume and cystic degeneration ratio affect specimen adequacy and cytological diagnosis time?

BACKGROUND

A fine needle aspiration biopsy (FNAB) of thyroid nodules - the least invasive and most accurate method used to investigate malignant lesions - may yield non-diagnostic specimens even under ultrasonographic guidance.

PURPOSE

To evaluate the effects of thyroid nodule volume and extent of cystic degeneration on both the non-diagnostic specimen ratio as well as cytopathologist's definitive cytological diagnosis time.

MATERIAL AND METHODS

In this single center study, FNAB was performed on 505 patients with single thyroid nodules greater than 10 mm. Nodule volume was calculated prior to FNAB and cystic degeneration ratio was recorded. All biopsies were performed by a single radiologist who also prepared specimen slides. Specimen adequacy and final diagnosis were made in the pathology laboratory by a single-blinded cytopathologist based on the Bethesda system. Definitive cytological diagnosis time was recorded upon reaching a definitive diagnosis.

RESULTS

The specimen adequacy ratio was 85.3%. The mean nodule volume of adequate specimens was larger than those of non-diagnostic samples (6.00 mL vs. 3.05 mL; P = 0.001). There was no correlation between nodule volume and cytopathologist's definitive cytological diagnosis time (r = 0.042). Biopsy of predominantly solid nodules yielded better specimen adequacy ratios compared to predominantly cystic nodules (87.8% vs. 75.3%; P = 0.028). Definitive cytological diagnosis times were longer in predominantly cystic nodules compared to predominantly solid nodules (376 s vs. 294 s; P = 0.019).

CONCLUSION

Predominantly cystic nodules are likely to benefit from repeated nodular sampling until the specimen is declared adequate by an on-site cytopathologist. If a cytopathologist is not available, obtaining more specimens per nodule may achieve desired adequacy ratios.

Diagnostic accuracy of fine needle aspiration cytology of thyroid and evaluation of discordant cases

INTRODUCTION

The main role of fine needle aspiration cytology (FNAC) lies in differentiating between a malignant and benign thyroid nodule. It greatly influences the treatment decision. The current study was undertaken to evaluate the cytology-histopathology correlation and to analyze the cause of diagnostic errors with an eventual aim to improve diagnostic accuracy.

MATERIALS AND METHODS

This is a retrospective study comparing cytology and corresponding histopathology report in 724 thyroid cases. The statistical analysis included false positive rate, false negative rate, sensitivity, specificity, positive predictive value, negative predictive value and accuracy.

RESULTS

On cytological examination, 635/724 were reported as benign, 68 malignant and 21 suspicious. On histopathological examination, 626/635 cases were confirmed as benign but there were 9 discordant cases. Among the other cases histopathology diagnosis of malignancy matched in 66/68 and 11/21 cases. Diagnosis correlated in 703/724 cases (97%) [p<0.001]. False positive and false negative rates were 1.9% and 10.5%, respectively. The sensitivity and specificity were 89.5% and 98%, respectively. The positive predictive value was 84.6% and negative predictive value was 98.6%. Accuracy of FNA was 97%.

CONCLUSION

In spite of high accuracy of FNAC in differentiating between a benign and malignant lesion, certain pitfalls should be kept in mind. The common false negative diagnoses were follicular pattern cases which constitute a 'gray zone', cystic papillary thyroid carcinoma (PTC) and papillary microcarcinoma. The reason for false positive diagnoses was the occurrence of nuclear features characteristic of PTC in other thyroid lesions. Awareness of pathologist regarding these pitfalls can minimize false negative/positive diagnoses.

The diagnostic accuracy of ultrasound-guided fine-needle aspiration biopsy for thyroid nodules three centimeters or larger in size

BACKGROUND AND PURPOSE

Whether under ultrasonography (US) guidance or not, fine-needle aspiration biopsy (FNAB) has some limitations, particularly in larger nodules. In this study, we aimed to evaluate the diagnostic value of US-guided fine-needle aspiration biopsy (US-FNAB) in thyroid nodules equal to or larger than 3 cm.

MATERIALS AND METHODS

Data of 267 patients operated for nodular goiter in the period of January 2006 and March 2012 were reviewed retrospectively. The study group (40 males, 104 females; mean age 42.3 ± 12.3, between 17 and 71) consisted of patients with nodules with a diameter of 3 cm or larger. Patients with nodules less than 3 cm in diameter were considered as the control group (27 males, 96 females; mean age 44.4 ± 11.9, between 18 and 71).

RESULTS

For nodules smaller than 3 cm, US-FNAB had an accuracy rate of 60% and a false negativity rate of 21.9%. In nodules equal to or larger than 3 cm, the accuracy rate of US-FNAB was 80%, with a false negativity rate of 6.7%. Malignancy was observed in 16% of the study group and 42.3% of the control group.

CONCLUSION

This study showed that increased nodule diameter is not associated with limitations in the diagnostic value of US-FNAB. We also found that the malignancy rate was smaller for larger nodules. This finding reflects the importance of accurate and rational diagnostic work-up and clinical management for detecting malignancy and surgical decision-making.

False negative cytology in large thyroid nodules

BACKGROUND

Controversy exists regarding the accuracy of fine-needle aspiration (FNA) in large thyroid nodules. Recent surgical series have documented false-negative rates ranging from 0.7 to 13 %. We examined the accuracy of benign FNA cytology in patients with thyroid nodules ≥3 cm who underwent surgical resection and identified features characteristic of false-negative results.

METHODS

We retrospectively studied all thyroidectomy specimens between January 2009 and October 2011 and identified nodules ≥3 cm with corresponding benign preoperative FNA cytology. We collected clinical information regarding patient demographics, nodule size, symptoms, sonographic features, FNA results, and final surgical pathology. For comparison, we analyzed nodules <3 cm from this cohort also with benign FNA cytology.

RESULTS

A total of 323 nodules with benign preoperative cytology were identified. Eighty-three nodules were <3 cm, 94 nodules were 3-3.9 cm, and 146 nodules were ≥4 cm in size. The false-negative rate was 11.7 % for all nodules ≥3 cm and 4.8 % for nodules <3 cm (p = 0.03). Subgroup analysis of nodules ≥3 cm revealed a false-negative rate of 12.8 % for nodules 3-3.9 cm and 11 % for nodules ≥4 cm. Age ≥55 years and asymptomatic clinical status were the only patient characteristics that reached statistical significance as risk factors. Final pathology of the false-negative specimens consisted mainly of follicular variant of papillary thyroid cancer and follicular thyroid cancer.

CONCLUSIONS

When referred for thyroidectomy, patients with large thyroid nodules demonstrate a modest, yet significant, false-negative rate despite initial benign aspiration cytology. Therefore, thyroid nodules ≥3 cm may be considered for removal even when referred with benign preoperative cytology.

Impact of thyroid nodule size on prevalence and post-test probability of malignancy: a systematic review

OBJECTIVES/HYPOTHESIS

Large thyroid nodules may be associated with higher risk of malignancy and less-accurate fine-needle aspiration (FNA) results, but there is currently no overarching consensus. We therefore tested two null hypotheses: 1) thyroid nodule size >3 to 4 cm is not associated with a higher baseline prevalence of malignancy (i.e., the associated pretest probability is the same, regardless of size), and 2) thyroid nodule size >3 to 4 cm is not associated with worse diagnostic accuracy (i.e., the associated sensitivity, false-negative rate, and post-test probability of malignancy is not affected by nodule diameter).

STUDY DESIGN

Computerized searches of PubMed, Embase, and The Cochrane Library through July 2013 were performed, supplemented with manual searches.

METHODS

A priori criteria were defined to determine inclusion and exclusion of studies. Searches and data extraction were performed by independent reviewers and focused on FNA histopathologic findings and their relationship to nodule size, study design, and potential confounders.

RESULTS

Criterion-meeting studies (n = 15) included a total of 13,180 participants. The preponderance of prospective comparative studies showed a statistically significantly higher prevalence of malignancy in large nodules. Although data are mixed, evidence from the best-reported studies suggests sensitivity, false-negative rates, and frequency of true negatives among benign FNA results are worse in large nodules.

CONCLUSIONS

Large nodules have a higher pretest probability of malignancy. Data from larger studies suggest reduced FNA diagnostic accuracy in nodules >3 to 4 cm in diameter. Surgery represents a reasonable clinical option for nodules >3 cm.

What is the Role of Diffusion Weigh Magnetic Resonance Imaging in Evaluation of Thyroid Nodules?

This study aimed to compare ultrasonography (US), contrast-enhanced computed tomography (CCT) of the neck, and diffusion-weigh magnetic resonance imaging (DW-MRI) in differentiating between benign and malignant nodules while approaching to thyroid nodules, and to estimate sensitivity and specificity of these methods. On thyroid US, echogenicity, calcification, presence/absence of halo, nodule size being larger/smaller than 20 mm, and nodule nature (cystic/solid nature) were evaluated. Findings on CCT of the neck were grouped according to the heterogeneity/homogeneity, presence/absence of enhancement, and intensity. On DW-MRI, diffusion restriction was evaluated. The findings of these tests were compared with postoperative histopathological findings, and specificity and sensitivity of the tests in differentiating malignant and benign nodules were assessed. The study included 38 patients (34 females, 4 males). The sensitivity and specificity of DW-MRI were 20 and 75 %, respectively. Presence of a >20 mm nodule in thyroid US had the highest sensitivity, whereas thyroid fine-needle aspiration biopsy (FNAB) had the highest specificity in detecting malignancy. The sensitivities and specificities of CCT of the neck and DW-MRI appeared relatively low. Evaluation of thyroid US findings together with thyroid FNAB findings provided high specificity and sensitivity and yielded better results than findings of CCT of the neck and DW-MRI.

Ultrasound-guided fine-needle aspiration of thyroid nodules: does size matter?

PURPOSE

Some authors have questioned the benefit of fine-needle aspiration (FNA) of thyroid nodules ≥ 4 cm. They report that the results of the FNA are not as reliable when compared to nodules <4 cm. The aims of this study are to evaluate the accuracy and predictive values of ultrasound-guided FNA (USFNA) of thyroid nodules ≥ 4 cm and compare these findings to nodules <4 cm.

METHODS

A retrospective study of 998 patients who underwent thyroid surgery between 2006 and 2012 at the McGill University Thyroid Cancer Center was performed. USFNA and post-operative pathology diagnoses of nodules ≥ 4 cm versus those <4 cm were compared. Pre-operative USFNA results were divided into three groups: benign, indeterminate, and malignant/suspicious for malignancy subgroups. Post-operative results were separated into benign and malignant groups.

RESULTS

There were 225 patients with nodules ≥ 4 cm and 773 patients with nodules <4 cm. The sensitivity, specificity, positive predictive value and negative predictive value for USFNA of nodules ≥ 4 cm were 84.62% (CI 71.91-93.10), 91.49% (CI 79.6-97.58), 91.67% (CI 80.0-97.63) and 84.31% (CI 71.4-92.95), respectively. The sensitivity, specificity, positive predictive value and negative predictive value for USFNA of nodules <4 cm were 90.48% (CI 86.1-93.8), 85.92% (CI 75.6-93.02), 95.8% (CI 92.41-97.96) and 71.76% (CI 60.95-81.0), respectively. The difference in diagnostic accuracy of USFNA between both groups was not statistically significant (p>0.05).

CONCLUSION

This study shows that the sensitivity, specificity, positive predictive value and negative predictive value for USFNA of nodules ≥ 4 cm are similar to that of smaller nodules. It is therefore suggested that these nodules undergo USFNA.