Diagnostic accuracy of Bethesda system for reporting thyroid cytopathology: an institutional perspective

Critical Appraisal of the 2017 Bethesda System for Reporting Thyroid Cytopathology with Cytohistological Concordance and Estimation of Risk of Malignancy - An Institutional Study

Aim

Bethesda System for reporting thyroid cytopathology established in 2009 was updated for the first time in 2017. Since its introduction very few studies have been done on the utility of recently introduced "The 2017 Bethesda System for Reporting Thyroid Cytopathology" (TBSRTC II) and estimation of risk of malignancy in various categories.

Material and methods

This was a prospective study done on thyroid lesions in which lesions were evaluated cytologically and classified according to TBSRTC II. Histopathological correlation was done, wherever possible. ROM was calculated for each Bethesda category in both ways as per TBSRTC II i.e. with NIFTP and excluding NIFTP from the malignant category.

Results

Using 2017 TBSRTC, 190 cases of thyroid FNACs were classified into 6 diagnostic categories. Cytohistological correlation was available in 60 cases. ROM was calculated which changed only in category III and V as only these two categories showed one case each of NIFTP. However there was an overestimation of ROM in category II and III as there are selection biases and not all thyroid nodules underwent surgical resections.

Conclusion

To conclude, the risk of malignancy calculated in two ways in the recent 2017 Bethesda system may have higher clinical relevance as those lesions with high ROM are defined for surgical excision. Thus we recommend that "The 2017 Bethesda system for Reporting Thyroid Cytopathology" should be implemented uniformly in our country as it provides a homogenous and standardised terminology resulting in better management of patients with thyroid nodular disease.

Deep learning-based cell segmentation for rapid optical cytopathology of thyroid cancer

Fluorescence polarization (Fpol) imaging of methylene blue (MB) is a promising quantitative approach to thyroid cancer detection. Clinical translation of MB Fpol technology requires reduction of the data analysis time that can be achieved via deep learning-based automated cell segmentation with a 2D U-Net convolutional neural network. The model was trained and tested using images of pathologically diverse human thyroid cells and evaluated by comparing the number of cells selected, segmented areas, and Fpol values obtained using automated (AU) and manual (MA) data processing methods. Overall, the model segmented 15.8% more cells than the human operator. Differences in AU and MA segmented cell areas varied between - 55.2 and + 31.0%, whereas differences in Fpol values varied from - 20.7 and + 10.7%. No statistically significant differences between AU and MA derived Fpol data were observed. The largest differences in Fpol values correlated with greatest discrepancies in AU versus MA segmented cell areas. Time required for auto-processing was reduced to 10 s versus one hour required for MA data processing. Implementation of the automated cell analysis makes quantitative fluorescence polarization-based diagnosis clinically feasible.

Study of Fine Needle Aspiration Cytology (FNAC) of Thyroid Gland According to the Bethesda System

BACKGROUND

 Fine needle aspiration cytology (FNAC) of thyroid gland is a powerful diagnostic tool for thyroid nodules. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) classifies thyroid FNAC findings into six categories. It is a standardized, simple, and convenient method of reporting which also provides guidelines for management.

AIMS AND OBJECTIVES

 To study the cytomorphology of thyroid lesions and classify them as per TBSRTC. Determine the epidemiology and distribution of various thyroid lesions in our tertiary care hospital. Correlation of cytopathology with histopathological diagnosis in cases which were operated in our hospital.

METHODS AND MATERIAL

 This is a prospective analytical study of 105 patients with clinically enlarged thyroid gland presenting at G.K. General Hospital, Bhuj during July 2018 to August 2020. FNAC smears of these patients were studied and correlated with histopathology wherever available.

RESULTS

 Out of a total 105 cases, 94 were non-neoplastic, eight were neoplastic, and three were unsatisfactory for evaluation. There were 94 cases in the benign category (category II), with colloid goiter being the most common cytological diagnosis (38 cases). There were no cases in categories III and V, respectively. On cytology, two cases in category IV were diagnosed as follicular neoplasm. Category VI had six cases comprising papillary carcinoma of thyroid (five cases) and medullary carcinoma of thyroid (one case). Out of a total 105 cases, 55 patients were operated in our center and hence their cytopathological findings were correlated with histopathological findings. Out of 55 operated cases, 45 cases (81.8%) had benign lesion and 10 cases (18.2%) were malignant. The sensitivity of FNAC was 70% and specificity was 100%.

CONCLUSIONS

 Thyroid cytology proves to be a reliable, simple, and cost-effective first-line diagnostic procedure with high patient acceptance and with rare, usually easily treated and not life-threatening complications. The Bethesda system is very useful for a standardized and reproducible system of reporting thyroid FNAC. It satisfactorily correlates with the histopathological diagnosis and helps in comparing results amongst various institutes.

Fluorescence Polarization Imaging of Methylene Blue Facilitates Quantitative Detection of Thyroid Cancer in Single Cells

Simple Summary

Accurate diagnosis of thyroid fine-needle aspiration cytology is a significant clinical challenge. A method to detect thyroid cancer at the cellular level would be invaluable to reduce diagnostic uncertainty and improve clinical decision making. We studied the ability of confocal fluorescence polarization imaging of an exogenous fluorophore, methylene blue, to provide quantitative discrimination of cancerous cells in human samples. Our results indicate that fluorescence polarization imaging provides a reliable biomarker of thyroid cancer and holds the potential to shift the paradigm of cellular level cancer diagnosis from subjective visual assessment to objective measurement.

Abstract

Background: Diagnostic accuracy of the standard of care fine-needle aspiration cytology (FNAC) remains a significant problem in thyroid oncology. Therefore, a robust and accurate method for reducing uncertainty of cytopathological evaluation would be invaluable. Methods: In this double-blind study, we employed fluorescence emission and quantitative fluorescence polarization (Fpol) confocal imaging for sorting thyroid cells into benign/malignant categories. Samples were collected from malignant tumors, benign nodules, and normal thyroid epithelial tissues. Results: A total of 32 samples, including 12 from cytologically indeterminate categories, were stained using aqueous methylene blue (MB) solution, imaged, and analyzed. Fluorescence emission images yielded diagnostically relevant information on cytomorphology. Significantly higher MB Fpol was measured in thyroid cancer as compared to benign and normal cells. The results obtained from 12 indeterminate samples revealed that MB Fpol accurately differentiated benign and malignant thyroid nodules. Conclusions: The developed imaging approach holds the potential to provide an accurate and objective biomarker for thyroid cancer, improve diagnostic accuracy of cytopathology, and decrease the number of lobectomy and near-total thyroidectomy procedures.

Application of the Bethesda system for reporting thyroid cytopathology for classification of thyroid nodules: A clinical and cytopathological characteristics in Bhutanese population

INTRODUCTION

The existence of baseline data on the spectrum of thyroid nodules in Bhutanese patients is unknown. Fine-needle aspiration cytology (FNAC) is regarded as the gold standard diagnostic test for pre-op assessment of thyroid lesions.

MATERIALS AND METHODS

We conducted a retrospective study, involving 765 patients who underwent FNAC of the thyroid gland, at Jigme Dorji Wangchuck National Referral Hospital, Thimphu, between January-2018 to December-2020. We aimed to assess the cytomorphological spectrum of thyroid nodules, classify them as per The Bethesda system for reporting thyroid cytopathology (TBSRTC), assess risk of malignancy (ROM), and evaluate the accuracy of FNAC in diagnosing thyroid malignancy.

RESULTS

Colloid nodule (37.4%) and papillary thyroid carcinoma (4.2%) constituted the majority of benign and malignant cytological diagnoses, respectively. According to TBSRTC, majority of the cases (82.0%) fell under the Bethesda II category. Bethesda III was the least common (1.4%) category. As compared to histopathological diagnosis; the sensitivity, specificity, positive and the negative predictive values of FNAC in diagnosing thyroid malignancy were 90.0%, 93.3%, 93.10%, and 90.32% respectively. The ROM increased concurrently with the grade of the Bethesda category and was more or less close to the ROM reference range, published in the TBSRTC.

CONCLUSION

Benign thyroid nodules (82.0%) constituted a majority of thyroid nodules in Bhutanese patients. FNAC was found to be reliable in detecting thyroid malignancy. From the literature, TBSRTC was found to be a more convenient method for reporting thyroid cytology. Henceforth, as most institutes, we plan to implement TBSRTC for reporting thyroid cytopathology.

Utility of Fine Needle Aspiration Cytology in the Evaluation of Lymphadenopathy

Introduction

Fine needle aspiration cytology (FNAC) is a quick, effective and relatively inexpensive technique to evaluate the visibly accessible superficial masses. As cervical, axillary and inguinal lymphadenopathies are commonly encountered clinical problems, in this study, we evaluated the utility of FNAC for assessment of lymphadenopathy.

Methods

A retrospective observational study was conducted in the Department of Cytopathology, Liaquat National Hospital and Medical College, over the duration of three years. A total of 559 cases were included in the study that underwent FNAC. After palpation, two to three passes were performed with a 22-23 gauge needle along with a plunger for FNAC. The obtained material was spread on three slides that were then stained with hematoxylin and eosin (H & E), Papanicolaou (PAP), and Diff-Quik methods. The remaining material was used for cell block preparation.

Results

The mean age of the patients was 37.05±18.03 years. In 98.7% of cases, the material was adequate for a satisfactory cytological examination. The most common site of FNAC was the cervical lymph node and tuberculous lymphadenitis (37%) was the most common diagnosis on FNAC, followed by reactive lymphadenitis (27.2%). Reactive lymphadenitis was seen more frequently in the younger age group (<15 years), whereas metastatic carcinoma was more commonly seen in the older age group (>50 years). Tuberculous lymphadenitis was noted more frequently in the middle age group (16-35 years). Moreover, tuberculous lymphadenitis was noted more commonly in cervical lymph nodes, while metastatic carcinoma was more frequently observed in axillary and inguinal lymph node FNACs.

Conclusion

FNAC is a quick and reliable method to categorize the cause of lymphadenopathy into reactive, inflammatory/infectious, metastatic, and lymphoproliferative, avoiding the necessity of an incisional/trucut biopsy. Moreover, age, gender, and site of involvement are useful predictors of the cause of lymphadenopathy. We noted that in the younger age group, reactive lymphadenitis was more common, whereas tuberculous lymphadenitis and metastatic carcinoma were more frequent in middle and older age groups, respectively. On a similar note, tuberculous lymphadenitis was more frequent in cervical lymph nodes than axillary and inguinal lymph nodes, while metastatic carcinoma was more common in these latter two sites.

Indian experience of AUS/FLUS diagnosis: is it different from rest of Asia and the West?-A systematic review and meta-analysis

Background

Atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) is the most heterogeneous subcategory of the Bethesda system for thyroid cytopathology with laid down permissible limits of frequency and risk of malignancy (ROM). Due to differences in thyroid clinical practice worldwide, variations have been found in frequency, resection rates (RR) and ROM. Therefore, this systematic review and meta-analysis of AUS/FLUS across different regions was conducted and comparison of data from India was done with the rest of Asia and the West.

Methods

We searched PubMed and Google search engines from January 2009-Dec 2019 using terms "AUS Thyroid" and "FLUS Thyroid". Meta-analysis was performed using DerSimonian-Laird method and 95% confidence intervals were calculated using random effects model. Independent samples t-test was used to compare frequency, RR, and ROM of AUS/FLUS between India, rest of Asia and the West.

Results

Out of 15,000 studies on internet, 60 (18 Indian, 12 Asian and 30 Western) were included. Total aspirates were 201,657; 14,279 Indian, 62,448 Asian, 124,930 Western. Pooled estimates were: frequency 7.3% (6.3-8.3%), RR 41.9% (37.4-46.6%), ROM 33.3% (26.8-39.9%). Pooled prevalence of rate did not vary significantly across the three regions. Pooled prevalence of RR was highest in India (52.9%) and lowest in rest of Asia (26.5%); of ROM was highest in Asia (45.9%), lowest in the West (26.3%) (P<0.01). Statistical analysis demonstrated publication bias, limited to Indian and Western studies. Papillary thyroid carcinoma was the most common surgical diagnosis (87.9%; 1,082/1,231).

Conclusions

This meta-analysis showed differences in thyroid clinical practice followed in India, rest of Asia and the West. Although pooled prevalence of rate of AUS/FLUS was similar across the three, pooled RR and ROM varied. AUS/FLUS nodules were more frequently resected in Indian and Western studies than in rest of Asia. ROM was higher than recommended values in all three areas, being intermediate for India.

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

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

Differences in cytopathologist thyroid nodule malignancy rate

OBJECTIVES

The accuracy of a cytological diagnosis obtained by fine needle aspiration is influenced by several factors including the technique used and the experience of both the aspirator as well as the cytologist. In this project we planned to evaluate the interobserver differences of thyroid nodule cytopathology in our medical centre.

METHODS

The study was conducted using retrospective pathology reports from a single academic centre from August 2013 to September 2017. We compared the sensitivity, specificity, negative and positive predictive values, malignancy rates, and accuracy of two cytopathologists who evaluated thyroid nodules.

RESULTS

We included 287 fine needle aspirations of thyroid nodules in the study. Approximately one fifth (18.5%) of patients had surgery and the rate of malignancy was 40%. There was a similar frequency of use of all thyroid Bethesda system (TBS) categories with the exception of TBS 3 (8.0% and 21.2%, P = .01). As a consequence, the malignancy rate was different in TBS 3 category (40% vs 17%, P = .545).

CONCLUSIONS

There are interobserver differences in the evaluation of thyroid nodules. Clinicians should be aware of such differences because they affect the malignancy rate in each TBS category.

Diagnostic accuracy of fine needle aspiration biopsy in pediatric small round cell tumors

Objective

Fine needle aspiration biospy (FNAB) is a simple, cost effective procedure, which can be carried out in the out-patient department. The objective of our study was to determine the diagnostic accuracy of fine needle aspiration biopsy in small round cell tumors of childhood, keeping histopathology as the gold standard.

Results

Out of these 50 cases, 35 (70%) were small round cell tumors and 15 (30%) cases of other childhood malignancies and certain reactive conditions. In our study, the most common malignant small round cell tumor (SRCT) on histopathology was Wilms tumor (10 cases) followed by non Hodgkin lymphoma (9 cases). FNAB results were correlated with the histological findings and the diagnostic accuracy of SRCT came out to be 98%. The sensitivity and specificity of FNAB in diagnosing SRCT was 97% and 100% respectively. FNAB was found to be a very useful technique in the initial evaluation of any palpable lesion of childhood. Although the small round cell tumors appear cytologically similar, in the hands of experienced cytopathologists, the subtle morphological features can help towards the final diagnosis. In addition, clinical and radiological findings are invaluable assets, which help to reach the final diagnosis.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3678-x) contains supplementary material, which is available to authorized users.

Evaluation of thyroid nodules classified as Bethesda category III on FNAC

Background:

The Bethesda (BSRTC) category III has been ascribed a malignancy rate of 5–15%, however, the probability of malignancy remains variable.

Aim:

To evaluate category III with respect to its rate and risk of malignancy and substratify it.

Settings and Design:

Atypia of undetermined significance/Follicular lesion of undetermined significance (AUS/FLUS) percentage, cytohistological correlation, and risk of malignancy were analyzed and substratification was done.

Material and Methods:

Category III cases over a 2-year period were analyzed retrospectively.

Statistical Analysis:

Two-tailed Fisher exact test, with a level of significance set at 0.05, was performed for data analysis.

Results:

Of 1169 thyroid fine needle aspirations (FNAs), 76 (6.5%) were category III. A total of 48 patients had follow up; 24 patients underwent surgery, 12 repeat FNA, and 12 were clinically followed. Repeat FNA cytology was unsatisfactory in 8.3%, benign in 66.7%, AUS in 8.3%, and follicular neoplasm in 16.7%. Of the 24 operated, 8 (33.3%) were malignant (follicular variants of papillary thyroid carcinoma), 5 (20.8%) were follicular adenomas, and 11 (45.8%) were non-neoplastic. Among all AUS/FLUS nodules with follow-up, malignancy was confirmed in 16.7% (8/48) whereas with nodules triaged to surgery only, the malignancy rate was 33.3% (8/24). Substratification into categories of “cannot exclude PTC” and “favor benign” helped detect malignancy better, as 85.7% cases in the first subcategory (P < 0.001) and none (P < 0.02) in the last proved malignant.

Conclusion:

Though the rate of Category III in our study is in accordance to BSRTC, the risk of malignancy in AUS/FLUS nodules is higher. Substratification of AUS/FLUS may help better patient management.

Fine needle aspiration biopsy of thyroid nodules: cytologic and histopathologic correlation of 1096 patients

Via routinely used thyroid function tests, scintigraphy and ultrasonography (USG), important information is obtained in the clinical and diagnostic practice for thyroid nodules. However, the distinction between benign and malignant lesions cannot precisely be performed with these tests. Thyroid fine needle aspiration biopsy (FNAB) is considered the most reliable diagnostic method in the differentiation between benign and malignant thyroid nodules. It has recently been likely to perform aspiration from deeper nodules via the implemention of FNAB along with USG. Today, in cytopathological examination of thyroid FNAB, standardized Bethesda System for Reporting Thyroid Cytopathology (BSRTC) system is used. Here, FNAB was performed in 1096 patients with thyroid nodules in the Medical School of Selcuk University between January 2009 and July 2014. Patients consisted of 919 women and 177 men between 12 and 87 years of age. Evaluated via BSRTC, the results were classified as unsatisfactory, benign, atypia (or follicular lesions) of undetermined significance (AUS), follicular neoplasm or lesions suspicious for follicular neoplasm (FN), suspected malignant and malignant. After FNAB, 183 patients were operated and evaluated histopathologically. Histological malignancy rates of the categories were as follows: 16% (5), 15% (6) 14% (1) 60% (9), 72% (18) and 97% (63), respectively. In our study, we aimed to compare FNAB results of thyroid nodules with histopathology results after thyroidectomy and to show the sensitivity and specificity of FNAB technique to be higher in the follow-up and diagnosis of thyroid lesions. Given the malignancy detection rate in the follow-up of patients whose cytology was reported as inadequate, we also consider follow-ups are important in these patients.