Factors that affect the false-negative outcomes of fine-needle aspiration biopsy in thyroid nodules

Delayed Cancer Diagnosis in Thyroid Nodules Initially Treated as Benign With Radiofrequency Ablation: Ultrasound Characteristics and Predictors for Cancer

OBJECTIVE

Regrowth after radiofrequency ablation (RFA) of symptomatic large thyroid nodules, initially treated as benign, sometimes turns out to be malignancies. This study aimed to assess the ultrasound (US) characteristics of thyroid nodules initially treated as benign with RFA and later diagnosed as cancers, predictive factors for cancers masquerading as benign, and methods to avoid RFA in these cancers.

MATERIALS AND METHODS

We reviewed the medical records of 134 consecutive patients with 148 nodules who underwent RFA between February 2008 and November 2016 for the debulking of symptomatic thyroid nodules diagnosed as benign using US-guided biopsy. We investigated the pre-RFA characteristics of the thyroid nodules, changes at follow-up after RFA, and the final surgical pathology.

RESULTS

Nodule regrowth after RFA was observed in 36 (24.3%) of the 148 benign nodules. Twenty-two of the 36 nodules were surgically removed, and malignancies were confirmed in seven (19.4% of 36). Of the 22 nodules removed surgically, pre-RFA median volume (range) was significantly larger for malignant nodules than for benign nodules: 22.4 (13.9-84.5) vs. 13.4 (7.3-16.8) mL (P = 0.04). There was no significant difference in the regrowth interval between benign and malignant nodules (P = 0.49). The median volume reduction rate (range) at 12 months was significantly lower for malignant nodules than for benign nodules (51.4% [0-57.8] vs. 83.8% [47.9-89.6]) (P = 0.01). The pre-RFA benignity of all seven malignant nodules was confirmed using two US-guided fine-needle aspirations (FNAs), except for one nodule, which was confirmed using US-guided core-needle biopsy (CNB). Regrown malignant nodules were diagnosed as suspicious follicular neoplasms by CNB. Histological examination of the malignant nodules revealed follicular thyroid carcinomas, except for one follicular variant, a papillary thyroid carcinoma.

CONCLUSION

Symptomatic large benign thyroid nodules showing regrowth or suboptimal reduction after RFA may have malignant potential. The confirmation of these nodules is better with CNB than with FNA.

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.

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.

Secondary thyroid malignancy - a rare clinical finding?

Metastases to the thyroid gland, while rarely seen in clinical practice, can pose a diagnostic and therapeutic challenge. Most commonly, they originate from lung, renal, and breast cancer, and are generally a sign of multiorgan metastatic disease. In most cases, metastases to the thyroid gland are diagnosed incidentally on imaging studies, since they are rarely symptomatic and often do not influence thyroid function tests. Thyroid ultrasonography and fine-needle aspiration biopsy play a pivotal role in their evaluation, as both classic immunocytochemical features, and more novel molecular markers can help in the differential diagnosis. Prognosis mainly depends on the biology of the primary tumor and its extension. Communication between clinicians is essential in such patients, in order to ensure that the treatment options are carefully balanced, thus raising the need for multidisciplinary teams in their management.

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.

A Nomogram to Predict the Outcome of Fine Needle Aspiration Cytology in Head and Neck Masses

Fine needle aspiration cytology (FNAC) is an important diagnostic tool for tumors of the head and neck. However, non-diagnostic or inconclusive results may occur and lead to delay in treatment. The aim of this study was to evaluate the factors that predict a successful FNAC. A retrospective search was performed to identify all patients who received an FNAC at the Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna. The variables were patients’ age and sex, localization and size of the punctured structure, previous radiotherapy, experience of the head and neck surgeon, experience of the pathologist and the FNAC result. Based on these parameters, a nomogram was subsequently created to predict the probability of accurate diagnosis. After performing 1221 FNACs, the size of the punctured lesion (p = 0.0010), the experience of the surgeon and the pathologist (p = 0.00003) were important factors for a successfully procedure and reliable result. FNACs performed in nodes smaller than 20 mm had a significantly worse diagnostic outcome compared to larger nodes (p = 0.0004). In conclusion, the key factors for a successful FNAC are nodal size and the experience of the head and neck surgeon and the pathologist.

Value of BRAF V600E in High-Risk Thyroid Nodules with Benign Cytology Results

BACKGROUND AND PURPOSE

Limitations of ultrasound-guided fine-needle aspiration include nondiagnostic, indeterminate cytology and false-negative results. The BRAF V600E mutation is a specific biomarker for papillary thyroid carcinoma. This study aimed to investigate the additional diagnostic role of the BRAF V600E mutation in high-risk thyroid nodules with benign cytology results.

MATERIALS AND METHODS

A total of 787 high-risk nodules in 720 patients underwent ultrasound-fine-needle aspiration. A subsequent BRAF V600E mutation test was performed on thyroid nodules with benign cytology. Final pathology confirmed thyroid nodules with benign cytology that were positive for the BRAF V600E mutation. Ultrasound was performed on thyroid nodules with benign cytology results that were negative for the BRAF V600E mutation. Fine-needle aspiration was repeated on thyroid nodules with enlarged size or changed ultrasound features.

RESULTS

Among the 787 nodules, 292 thyroid nodules had benign cytology results with 256 nodules negative for the BRAF V600E mutation and 36 nodules positive for the BRAF V600E mutation. Thirty-one nodules positive for the BRAF V600E mutation were confirmed malignant, and 5 nodules were confirmed benign by pathology. Fine-needle aspiration was repeated on 11 enlarged thyroid nodules with benign cytology findings that were negative for the BRAF V600E mutation. The results of repeat fine-needle aspiration were 4 benign nodules, 2 follicular neoplasms or suspected follicular neoplasms, 3 suspected malignancies, and 2 malignant nodules. Among the 36 thyroid nodules positive for the BRAF V600E mutation, 25 (69.4%) had ≥2 suspicious ultrasound features and 11 (30.6%) nodules had 1 suspicious ultrasound feature.

CONCLUSIONS

The BRAF V600E mutation test can detect papillary thyroid carcinomas that might be missed by fine-needle aspiration. We recommend that fine-needle aspiration be routinely accompanied by the BRAF V600E mutation test in high-risk thyroid nodules with ≥2 suspicious ultrasound features.

2017 Thyroid Radiofrequency Ablation Guideline: Korean Society of Thyroid Radiology

Thermal ablation using radiofrequency is a new, minimally invasive modality employed as an alternative to surgery in patients with benign thyroid nodules and recurrent thyroid cancers. The Task Force Committee of the Korean Society of Thyroid Radiology (KSThR) developed recommendations for the optimal use of radiofrequency ablation for thyroid tumors in 2012. As new meaningful evidences have accumulated, KSThR decided to revise the guidelines. The revised guideline is based on a comprehensive analysis of the current literature and expert consensus.

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.

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.

FNAC accuracy in diagnosis of thyroid neoplasms considering all diagnostic categories of the Bethesda reporting system: A single-institute experience

BACKGROUND

Thyroid fine-needle aspiration cytology (FNAC) is a valuable test used for diagnosing diseases of the thyroid gland.

AIMS

Using all satisfactory categories of the Bethesda system, this study aimed to determine the accuracy with which FNAC diagnoses thyroid neoplasms. We also discuss the factors that affect diagnosis accuracy.

SETTINGS AND DESIGN

A comparison was drawn between FNAC results and final histological diagnosis using samples collected over a period of 3 years.

MATERIALS AND METHODS

For all patients, age, sex, cytological features, and histological types were determined. All cases of false negative (FN) and false positive (FP) diagnosis were reanalyzed.

STATISTICAL ANALYSIS USED

The chi-square test and univariate analysis were performed to examine the relationship between different variables.

RESULTS

About 52% of the cases were found malignant, and they were of six different histological types. Papillary carcinoma was the commonest type of malignancy at 76.9%. The rate of malignancy was 63% in males and 49.4% in females. In two of the FN cases, the tumor had a diameter of ≥35 mm. Of the 12 FP cases, nine were in the follicular neoplasm or suspicious for follicular neoplasm Bethesda category. FNAC diagnosis had 95.2% sensitivity, 68.4% specificity, 83.3% positive predictive value, 89.6% negative predictive value, and 85.14% accuracy.

CONCLUSIONS

FNAC was found to have a high level of sensitivity and an acceptable degree of specificity in diagnosing different types of thyroid neoplasms. The presence of microfollicular structures or crowded cellular clusters is a challenge to diagnosis, particularly in low-quality specimens.

SAME-DAY FINE-NEEDLE ASPIRATION CYTOLOGY DIAGNOSIS FOR THYROID NODULES ACHIEVES RAPID ANXIETY DECREASE AND HIGH DIAGNOSTIC ACCURACY

OBJECTIVE

The time between the moment of referral for the diagnostic workup for thyroid nodules and the outcome can be worrisome for patients. In general, patients experience high levels of anxiety during the evaluation of a lesion suspicious for cancer. Therefore, the implementation of same-day fine-needle aspiration cytology (FNAC) diagnosis is becoming standard-of-care for many solid tumors. Our aim was to assess the feasibility of same-day FNAC diagnosis for thyroid nodules and to assess patient anxiety during the diagnostic process.

METHODS

For feasibility of same-day FNAC diagnosis, we assessed the proportion of patients receiving a diagnosis at the end of the visit. Accuracy was measured by comparing histology with the FNAC result. Patient anxiety was measured by the State Trait Anxiety Inventory at 6 moments during the diagnostic workup.

RESULTS

Of the 131 included patients, 112 (86%) were female, and the mean age was 53 years. All patients, except those with a nondiagnostic FNAC result (n = 26; 20%), had a diagnosis at the end of the day. There were only two discordant results. Anxiety levels at the beginning of the day were high throughout the group, State Trait Anxiety Inventory (STAI) score 43.1 (SD 2.0) and decreased significantly more in patients with a benign FNAC result (STAI score 30.2), compared to patients with a malignant or indeterminate result (STAI score 39.6).

CONCLUSION

Distress of patients with a thyroid nodule undergoing same-day FNAC diagnostics was high. Same-day FNAC diagnosis is feasible and accurate for the evaluation of thyroid nodules. Therefore, same-day FNAC diagnosis seems a safer, more patient-friendly approach to diagnose thyroid nodules.

Intact parathormone measurement 1 hour after total thyroidectomy as a predictor of symptomatic hypocalcemia

OBJECTIVE

Postoperative iPTH assay may predict significant hypocalcemia after thyroid surgery. The present study aimed to evaluate the ability of iPTH assay to monitor parathyroid function and to identify the risk of postoperative hypocalcemia in patients underwent thyroid surgery.

MATERIALS AND METHODS

One hundred patients participated in the study (7 male and 93 female). Hypocalcemia was defined as a serum calcium concentration less than 8.0 mg/dL and symptoms of hypocalcemia. Concomitant serum calcium and iPTH levels were measured before operation and at 1(st) h for iPTH, 24(th) h for calcium after thyroidectomy.

RESULTS

Postoperative hypocalcemia was observed in 31 patients. The mean postoperative serum calcium concentration in normocalcemic patients was 8.8 ± 0.5 mg/dL, whereas it was 7.6 ± 0.3 mg/dL in hypocalcemic patients. The mean postoperative 1(st) hour iPTH of patients in the hypocalcemia group was 9.1 ± 4.9 pg/mL, whereas patients of the normocalcemia group had a mean postoperative iPTH of 35.8 ± 20.2 pg/mL.

CONCLUSION

Postoperative 1(st) hour iPTH < 8 pg/mL with drop in iPTH level ≥ 81.5% together showed the highest diagnostic accuracy in predicting postoperative hypocalcemia.

Molecular characterization of 54 cases of false-negative fine-needle aspiration among 1347 papillary thyroid carcinomas

BACKGROUND

Fine-needle aspiration (FNA) has been widely accepted as the most crucial step in the preoperative assessment of thyroid nodules, but the false-negative rates are generally reported to be between 3.6% and 10.2%. To lower the overall incidence of this false-negative testing, new reporting systems encourage the molecular testing of thyroid nodules. However, to the authors' knowledge, the role of molecular testing in false-negative FNA has not yet been evaluated.

METHODS

In total, 1347 consecutive papillary thyroid carcinomas (PTCs) with both cytological and histological diagnoses were collected from the same center. A blinded revision of the false-negative cases was performed. An analysis of the BRAF and Ras genes in the false-negative cases was then performed.

RESULTS

The false-negative rate at the time of primary FNA diagnosis was 4.8% (65 of 1347 cases). False-negative cases were 15 follicular variant PTCs, 2 classical variant, and 1 solid variant that lacked peculiar PTC cytomorphological features. Adequate cellular material for molecular analysis was available only in 54 of the 65 false-negative cases. Mutations were found in 6 cases (11%), and Ras alterations were present in 16 cases (29.6%). The addition of molecular analysis decreased the false-negative rate to 0.4% (5 of 1347 cases).

CONCLUSIONS

The results of the current study confirm the feasibility of BRAF and Ras analysis in routine FNA. However, when the false-negative FNA rate is low, the cost-benefit analysis of the detection of BRAF and Ras mutations should be carefully evaluated. Consequently, the authors suggest that preoperative molecular assessment could be helpful for benign nodules, but only in the presence of clinical suspicion of malignancy.