Reproducibility of 'The Bethesda System for reporting Thyroid Cytopathology': A MultiCenter Study with Review of the Literature

Interobserver Reliability of Milan and Modified Milan System for Reporting Salivary Gland Cytopathology: An Institutional Experience

Background

In 2018, the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was published, defining a diagnostic categorization scheme. However, this system of classification was criticized due to its suboptimal diagnostic accuracy and low interobserver reliability. For these reasons, the modified Milan system was recently proposed by a few authors claiming it to be more clinically reliable. The present study aimed to analyze the interobserver reliability of MSRSGC and modified MSRSGC.

Methods

A total of 100 salivary gland fine-needle aspirations were reviewed over a 1-year period and classified by two independent observers according to MSRSGC and modified MSRSGC. Interobserver reproducibility was estimated using observed agreement and chance-corrected agreement (Cohen's kappa).

Results

An overall chance corrected agreement of 0.37 (fair) was obtained for the original Milan system and 0.41 (moderate) for the modified one. In addition, subcategories of modified MSRSGC performed better than the MSRSGC in terms of interobserver reliability.

Conclusion

The present study suggests that modified MSRSGC should be accepted worldwide as the clinical relevance of any categorization scheme requires diagnostic accuracy along with excellent interobserver reproducibility.

Repeat thyroid FNAC: Inter-observer agreement among high- and low-volume centers in Naples metropolitan area and correlation with the EU-TIRADS

Our institution (University Hospital "L. Vanvitelli" - Naples, Italy) is a high-volume (HV) center in Naples metropolitan area and many patients are referred there to repeat thyroid fine-needle aspiration cytology (FNAC) after initial FNAC performed in low-volume institutions (LV). The aims of the study were to 1) examine the inter-observer agreement between HV and LV institutions according to the Italian thyroid cytology system, and 2) explore how the discordant FNAC reports were distributed in the European Thyroid Imaging and Reporting Data System (EU-TIRADS) categories. All consecutive cases of repeat FNAC performed at University Hospital "L. Vanvitelli" from January 2016 to December 2021 were retrospectively reviewed. Fleiss' kappa (κ) was used to assess the inter-observer agreement, and categorical variables were compared by chi-square testing. P < 0.05 was considered statistically significant. A total of 124 nodules from 124 adults (mean age 49 years; mean maximum diameter 19 mm) were evaluated. Initial FNAC reports at LV were: 4 (3.2%) TIR1c, 64 (51.6%) TIR2, 48 (38.7%) TIR3A, 8 (6.5%) TIR3B, 0 TIR4, 0 TIR5. The overall FNAC reports were significantly different between the LV and HV institutions. At repeated FNAC, cytological diagnosis was unchanged in 64 (51.6%) cases including TIR2 and TIR3A results. A downgraded FNAC diagnosis (i.e., TIR2 vs TIR3A, TIR2 vs TIR3B) was observed in 36 (29%) nodules. An upgraded FNAC diagnosis (i.e., TIR3B vs TIR2, TIR3B vs TIR3A, TIR4 vs TIR3A, TIR5 vs TIR2, TIR5 vs TIR3B) was recorded in 24 (19.4%) nodules. The weighted inter-observer agreement between LV and HV institutions was poor (κ=0.133). Changed FNAC results were significantly (p=0.0023) more frequent in nodules at intermediate/high-risk (i.e., EU-TIRADS 4/5) than in those at no/low risk (EU-TIRADS 2/3) [i.e., 32/48 (66.7%) and 28/76 (36.8%), respectively]. Downgraded FNAC results were significantly more frequent in EU-TIRADS 2/3 (p=0.001) while upgraded FNAC were present only in EU-TIRADS 4/5 (24/24, 100.0%). The inter-observer agreement among LV and HV thyroid services was poor. The EU-TIRADS 4 and 5 categories included all the malignant nodules with FNAC results reclassified as higher risk (i.e., TIR3B-TIR4-TIR5) by the high-volume cytology service.

Low reproducibility of equivocal categories of the Bethesda System for Reporting Thyroid Cytology makes the associated risk of malignancy specific to the diagnostic center

PURPOSE

Equivocal categories (III, IV, V) of the Bethesda System for Reporting Thyroid Cytology (BSRTC) are characterized by high variability of the estimated risk of malignancy. The aim of the study was to analyze the reproducibility of classification of nodules into an equivocal category and the frequency of malignancy (FoM) observed in such categories.

METHODS

Five experienced cytopathologists from three centers (A, B, C) independently performed reclassification of smears obtained from 213 thyroid nodules with equivocal routine cytology and known results of the postoperative histopathological examination.

RESULTS

The interobserver agreement among all cytopathologists was poor, with a Krippendorff's alpha coefficient equaling 0.34. The intra-center agreement was higher than the inter-center (fair vs poor). Pathologists of the center A classified smears into categories II and III significantly less often and categories IV and V more often than pathologists of centers B and C. The joint FoM of nodules classified into any of categories IV-VI (regarded as an indication for surgery) was different among centers (A: 40.0%, B: 66.7%, C: 80.6%). The FoM of category III nodules with features of nuclear atypia (AUS) in center B and C was two times higher than that of other nodules of category III (FLUS), while in center A the FoM was similar.

CONCLUSIONS

The use of published data on the risk of malignancy in nodules of particular BSRTC categories without concern for the uniqueness of the diagnostic center may lead to erroneous conclusions.

The Papanicolaou Society of Cytopathology guidelines for respiratory cytology: Reproducibility of categories among observers

Introduction:

The Papanicolaou Society of Cytopathology (PSC) has developed a set of guidelines for reporting respiratory cytology. While the malignancy risk for each category is known, the interobserver reproducibility of these diagnostic categories has not been well described.

Methods:

Fifty-five cytologic specimens obtained by fine needle aspiration from the pulmonary nodules were independently reviewed by four board-certified cytopathologists and assigned to the diagnostic categories described by the PSC guidelines for respiratory specimens. Statistical analysis for diagnostic accuracy was performed for absolute agreement and chance-corrected agreement (kappa). Differences in frequency of distribution of diagnoses between raters were assessed using the Kruskal–Wallis test.

Results:

No significant differences in distribution of scores by raters were observed. On average, the absolute agreement was 49.5% and the chance-corrected agreement (kappa) was 20%. 34.5% of interrater comparisons were in full agreement, and total lack of agreement between the four categories was found in 3% of cases. Combining the “suspicious for malignancy” category with the “malignant” category did not significantly alter interrater agreement statistics.

Conclusions:

The PSC categories showed only fair reproducibility among four cytopathologists. Agreement between raters was at best fair and did not improve significantly when the categories “suspicious for malignancy” and “malignant” were combined. The most common source of disagreement appeared to be between the categories “suspicious” and “malignant.”

Reproducibility of "The Bethesda System for Reporting Thyroid Cytopathology:" A Retrospective Analysis of 107 Patients

Objectives:

Fine-needle aspiration cytology (FNAC) has emerged as an indispensable tool to discriminate thyroid lesions into benign or malignant for appropriate management. The need for simplicity of communication and standardization of terminology for thyroid FNAC reporting led to introduction of “The Bethesda system for reporting Thyroid Cytopathology” (TBSRTC) in a conference held at the National Cancer Institute in 2007. This study aims at establishing the reproducibility of TBSRTC for diagnosing thyroid lesions.

Materials and Methods:

The present study comprised thyroid FNAC from 107 patients retrospectively over a period of 1.5 year (June 2013 to December 2014), which were reviewed by two trained cytopathologists and re-categorized according to TBSRTC. The interobserver variation and reproducibility of the reporting system was statistically assessed using Cohen's kappa.

Results:

The cytopathologists were in agreement in 98 out of 107 cases (91.5%). Maximum concordance was noted in benign category (91 of 96 cases; 92.85%), followed by 2 cases each in nondiagnostic/unsatisfactory (ND/US) and follicular neoplasm/suspicious for follicular neoplasm (FN/SFN) category (2.04% each) and 1 case each in atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), suspicious for malignancy (SUS), and malignant category (1.02% each). The highest diagnostic disagreement was noted among ND/US and benign and benign and FN/SFN categories.

Conclusion:

The utilization of TBSRTC for reporting thyroid cytology should be promoted in our country because it provides a homogeneous, standardized, and unanimous terminology for cytological diagnosis of thyroid lesions. The present study could substantiate the diagnostic reproducibility of this system.

Thyroid Cytology in India: Contemporary Review and Meta-analysis

Fine-needle aspiration cytology (FNAC) is a screening test for triaging thyroid nodules, aiding in subsequent clinical management. However, the advantages have been overshadowed by the multiplicity of reporting systems and a wide range of nomenclature used. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was formulated in 2007, to give the world a uniform thyroid cytology reporting system, facilitating easy interpretation by the clinicians. Here, we review the status of thyroid FNAC in India in terms of various reporting systems used including a meta-analysis of the previously published data. An extensive literature search was performed using internet search engines. The reports with detailed classification system used in thyroid cytology were included. The meta-analysis of published data was compared with the implied risk of malignancy by TBSRTC. More than 50 studies were retrieved and evaluated. TBSRTC is currently the most widely used reporting system with different studies showing good efficacy and interobserver concordance. Ancillary techniques have, as of now, limited applicability and acceptability in thyroid cytology in India. Twenty-eight published articles met the criteria for inclusion in the meta-analysis. When compared with TBSRTC recommendations, the meta-analysis showed a higher risk of malignancy for categories I and III. Thyroid FNAC is practiced all over India. TBSRTC has found widespread acceptance, with most institutions using this system for routine thyroid cytology reporting. However, reasons for a high malignancy risk for categories I and III need to be looked into. Various possible contributing factors are discussed in the review.

A study of Galactin-3 on fine needle aspiration as a diagnostic marker differentiating benign from malignant thyroid neoplasm

Background & Objective:

Thyroid nodules are very common in our setup and their diagnosis on fine needle aspiration is not easy and is a taxing affair. It is a challenge to differentiate between follicular adenoma and follicular carcinoma without histology. Our objective was to investigate the role of Galectin-3 in fine needle aspirates of thyroid nodules as a prospective diagnostic marker and consequently its ability to differentiate benign from malignant neoplasms.

Methods:

The research was conducted at the department of Pathology, King Edward Medical University, in association with other teaching institutions of Lahore from June 2012 to July 2014.. Sixty cases of solitary thyroid nodules were included in the study. Haematoxylin and eosin staining of the fixed smears and Galectin-3 immunohistochemical staining of the sections prepared from the cell block was performed.

Results:

There were 60 patients in our study with a mean age of 33.35 years. The Bethesda system for reporting thyroid cytopathology was used to classify the smears and only categories IV, V and VI were included. On histological examination of the resected nodules there were 38.3% (23/60) cases of follicular adenoma, 46.6% (28/60) were of papillary carcinoma and follicular carcinoma made up to 15% (9/60) of all cases. Galectin-3 was negative in 100% (23/23) cases of follicular adenomas. Out of 37 malignant cases 65% lesions showed positivity, while 35% showed negativity for this immunomarker. Considering the malignant lesions, 75% cases of papillary carcinomas showed a positive reaction while only 33% of follicular carcinomas were positive for the immunomarker. This showed that the positive expression was more common in papillary as compared to follicular carcinomas.

Conclusion:

Galectin-3immunomarker is considerably expressed in malignant tumors, but it is not expressed in benign follicular lesions.

An evaluation of the diagnostic efficacy of fine needle aspiration biopsy in patients operated for a thyroid nodular goiter

BACKGROUND

Thyroid cancer (TC) comprises 1% of all carcinomas and is the most common malignancy of the endocrine system. The disease is more common in women, with its peak morbidity observed in 40-50-year-old patients. The main risk factors include radiation, iodine deficiency, hereditary background, and genetic mutations. Among all diagnosed thyroid nodules, 5%-30% will evolve into cancer. The gold-standard procedure in the preoperative evaluation of a nodular goiter, apart from ultrasonography, is fine needle aspiration (FNA) biopsy. The FNA biopsy is favored for its simplicity, safety, and high specificity and sensitivity rates.

AIM

The aim of our study was to evaluate the clinical efficacy of FNA based on the patients' register.

MATERIALS AND METHODS

In the Department of Surgery at the 4th Military Teaching Hospital in Wroclaw, 2,133 patients underwent thyroid surgery for thyroid goiter between 1996 and 2015. One hundred and eight cases of TC were diagnosed and of these, 66 patients had a preoperative FNA.

RESULTS

Fourteen FNA biopsies (21%) revealed cancer, all of which were confirmed in the postoperative histopathology, although six cases of FNA-diagnosed cancer revealed a different histological type postoperatively. Eighteen FNA biopsies (27%) were suspected of being malignant. A disturbingly high rate of "benign" FNA biopsies (32 cases; 48%) revealed TC after surgery.

CONCLUSION

It is of great importance that the quality and quantity of FNA biopsies that are performed have been improved, especially due to the wide adoption of the Bethesda cytological evaluation system. FNA biopsy remains an obligatory and valuable diagnostic tool in thyroid nodules, but it is still insufficient as a standard procedure. A preoperative biopsy should always be related to all the available clinical data in order to provide the best treatment option for each patient individually.

Morphometric Analysis of Thyroid Follicular Cells with Atypia of Undetermined Significance

BACKGROUND

Atypia of undetermined significance (AUS) is a category that encompasses a heterogeneous group of thyroid aspiration cytology. It has been reclassified into two subgroups based on the cytomorphologic features: AUS with cytologic atypia and AUS with architectural atypia. The nuclear characteristics of AUS with cytologic atypia need to be clarified by comparing to those observed in Hashimoto thyroiditis and benign follicular lesions.

METHODS

We selected 84 cases of AUS with histologic follow-up, 24 cases of Hashimoto thyroiditis, and 26 cases of benign follicular lesions. We also subcategorized the AUS group according to the follow-up biopsy results into a papillary carcinoma group and a nodular hyperplasia group. The differences in morphometric parameters, including the nuclear areas and perimeters, were compared between these groups.

RESULTS

The AUS group had significantly smaller nuclear areas than the Hashimoto thyroiditis group, but the nuclear perimeters were not statistically different. The AUS group also had significantly smaller nuclear areas than the benign follicular lesion group; however, the AUS group had significantly longer nuclear perimeters. The nuclear areas in the papillary carcinoma group were significantly smaller than those in the nodular hyperplasia group; however, the nuclear perimeters were not statistically different.

CONCLUSIONS

We found the AUS group to be a heterogeneous entity, including histologic follow-up diagnoses of papillary carcinoma and nodular hyperplasia. The AUS group showed significantly greater nuclear irregularities than the other two groups. Utilizing these features, nuclear morphometry could lead to improvements in the accuracy of the subjective diagnoses made with thyroid aspiration cytology.

Triage of patients with AUS/FLUS on thyroid cytopathology: effectiveness of the multimodal diagnostic techniques

The management of patients with thyroid cytopathologic diagnosis of atypia (or follicular lesion) of undetermined significance (AUS/FLUS) is a complex clinical problem. The purpose of this study was to develop a practical triage scheme based on multiple diagnostic tests in general use. We performed a retrospective cohort study involving 15,335 consecutive patients with a referral diagnosis of thyroid nodule between April 2011 and March 2015 using an institutional database. We obtained 904 patients with an initial cytopathologic diagnosis of AUS/FLUS who underwent repeat fine‐needle aspiration or core needle biopsy, 388 of whom had a corresponding histopathological diagnosis for excised index lesions. The diagnostic performance of ultrasound (US) findings, repeat biopsy, and BRAF^V600E mutation in cytopathologic specimens were evaluated individually or as a set. Of the 388 resected AUS/FLUS cases, 338 (87.1%) were thyroid cancer. The positive likelihood ratios (LRs) for BRAF^V600E mutation and repeat biopsy result of suspicious for malignant cell (SMC) or worse were 11.6 (95% CI = 1.7–77.8) and 13.7 (95% CI = 4.6–41.0), respectively. The absence of suspicious findings on US combined with cytologic result of less than SMC or negative BRAF^V600E mutation produced negative LRs ranging from 0.06 to 0.15, corresponding to negative predictive values of over 90% in both primary and referral settings. For patients with AUS/FLUS cytopathology, clinical decision making can be guided by a simple triage scheme based on US findings, repeat biopsy, or BRAF^V600E mutation.

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.

Review of the Bethesda System for Reporting Thyroid Cytopathology: a local study in Bohol Island, Philippines

OBJECTIVES

The aim of this study was to evaluate the adaptability and reproducibility of the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) in a local setting and to determine the risk of malignancy for each category.

MATERIALS AND METHODS

A retrospective cross-sectional study of 80 thyroid fine-needle aspiration cytology cases using the BSRTC with corresponding histopathology was done between September 2009 and December 2012. Agreement scores were calculated using kappa statistics.

RESULTS

Consensus among two readers was attained for 73 cases (91.25%). No disagreement was noted for the malignant cases. The strength of agreement was very good, with a kappa statistic of 0.90. The risk of malignancy observed histologically was as follows: benign 3%, atypia of undetermined significance (AUS) 50%, suspicious for follicular/Hürthle cell neoplasm 50%, suspicious for malignancy 78%, and malignant 100%.

CONCLUSION

In this study, there is an outstanding reproducibility for the classification scheme. The application of the BSRTC as the standardized reporting is readily adaptable and therefore its application in larger medical centers is highly recommended. Our findings of a higher risk of malignancy seen in AUS (50%) and malignant (100%) categories in those who underwent surgical resection corroborated other published studies. Conveying this risk to clinical colleagues is important and will facilitate optimal patient care.

Thyroid atypia of undetermined significance or follicular lesion of undetermined significance: an indispensable Bethesda 2010 diagnostic category or waste garbage?

OBJECTIVE

The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) was introduced in thyroid cytology in 2007 and is now generally accepted. BSRTC categories include a morphologic description and risk of malignancy as well as follow-up suggestions in each group. However, the category entitled 'atypia of undetermined significance or follicular lesion of undetermined significance' (AUS/FLUS) is problematic. This category is heterogeneous and has been overused so far.

STUDY DESIGN

Twenty-six studies were included in a meta-analysis. In addition to AUS/FLUS percentage, we analysed repeated AUS/FLUS percentage, cytological and histological correlations, and risk of malignancy and neoplasm for AUS/FLUS. Furthermore, stratification, inter- and intra-observer variability, and the possibility of a switch to another category and its clinical consequences were reviewed.

RESULTS

Out of a total of 81,833 cases, AUS/FLUS accounted for 10.9%, with a 34% risk of malignancy. Persistent AUS/FLUS was found in 21.6% in repeated cytology. Cytohistological correlation was analysed from 16 studies (4,964 cases), revealing 10.4% as AUS/FLUS and a 21.5% risk of malignancy.

CONCLUSIONS

An AUS/FLUS category seems to be currently reasonable with clearly defined cytomorphological criteria which do not correspond unequivocally with those of the other categories. An AUS/FLUS category is justified and possible means of its improvement with immunohistochemistry, molecular analysis and imaging are discussed.

Association between Pituitary Langerhans Cell Histiocytosis and Papillary Thyroid Carcinoma

Here we report a case of panhypopituitarism caused by pituitary Langerhans cell hystocitosis (LCH) in a 22-year-old woman affected by papillary thyroid carcinoma (PTC). Although several cases of the coexistence of PTC and LCH within thyroid tissue have been described in relative literature, in this case, the patient presented a unique suprasellar retrochiasmatic histocytosis localization which, to the best of our knowledge, had never been described before in association with PTC. Even if this aspect is not addressed in the present case report, it is worth noting that about 50% of the patients affected either by LCH or PTC are characterized by activating mutations of the proto-oncogene BRAF. This, along with other clinical studies, may warrant further biomolecular large-scale case study investigations in order to evaluate a possible connection between the 2 conditions and shed light on the etiology of these diseases, which are still largely unknown.