Pre-Operative Cytological Evaluation of Thyroid Nodules According to the 2017 Bethesda System

Research Article

Austin J Pathol Lab Med. 2021; 8(1): 1028.

Pre-Operative Cytological Evaluation of Thyroid Nodules According to the 2017 Bethesda System

Archondakis S*

Department of Cytopathology, Alpha Prolipsis Cytopathology Laboratories, Greece

*Corresponding author: Stavros Archondakis, Department of Cytopathology, Alpha Prolipsis Cytopathology Laboratories, 1 Xenias St, Athens, 12137, Greece

Received: December 31, 2020; Accepted: January 12, 2021; Published: January 19, 2021


Objective: This study aims to present the experience of the implementation of the Bethesda system for reporting thyroid cytopathology in Alpha Prolipsis Medical Laboratories, a private medical laboratory located in Athens, Greece.

Methods: 617 FNAs, performed since 2017, were included in the study. Reports were issued according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Aspirates were prepared with both conventional and liquid based cytology methods and were evaluated by two board certified cytopathologists. Diagnostic reproducibility and accuracy were evaluated. In 106 of these cases the cytological diagnosis was histologically confirmed.

Results: Out of the 533 cases cytologically diagnosed as benign, 7 false negative results were obtained by FNA, whereas out of the 37 cytological diagnoses of probably or definitively malignant tumors one case was found histologically to be follicular adenoma. In this trial, the diagnostic accuracy of FNA was 96.7%, the specificity 94% and the sensitivity 87%.

Conclusions: Our results show that FNA is a valuable examination technique in the preoperative evaluation of thyroid nodules. The integration of the 2017 Bethesda System for Reporting Thyroid Cytopathology is effective with an overall accuracy around 92%.

Keywords: Thyroid; Fine-needle aspiration; Risk of malignancy; Reproducibility; Liquid-based cytology


Thyroid nodules may be found in up to 60% of the population. The majority of thyroid nodules are benign [1,2]. Moreover, an incidental malignancy is found on histological assessment in 3-16 % of patients undergoing thyroidectomy for benign disease [1-3]. The incidence of thyroid cancer has increased worldwide in the past few decades [1-3]. FNA was recognized as a first- line diagnostic method for the evaluation of thyroid lesions in northern Europe during the period between 1950 and 1960 [2,4,5]. During the last 2 decades, its diagnostic value has been widely accepted. Nowadays, FNA consists a very useful examination due to its high accuracy in the preoperative assessment of solitary thyroid nodules, contributing to the appropriate management of the patient by decreasing the number of unnecessary thyroidectomies [1,2,5]. It is estimated that thyroid carcinomas consist only 1, 5% of the total thyroid neoplasms and cause the 0, 4% of cancer deaths [1,2]. Thyroid cancer frequency is about 0, 5-10 per 100.000 people [1,2]. Thyroid carcinomas are further subclassified in papillary, follicular, medullary, Hurthle cell, undifferentiated and metastatic. Lymphomas have also been dignosed by FNA [2,5].

Until 2007, 20-30% of FNA reports could not be classified as either benign or malignant, partly because of factors such as the lack of a widely accepted standardized reporting format, the use of multiple, often overlapping, cytological terms in descriptive reports lacking a definite diagnosis [1,2,6]. A reporting system should be intronduced in order to provide definite indications concerning patient management. The proposed reporting system should be easy in everyday practice and guarantee good intra- and interobserver reproducibility for each diagnostic category [1,6,7]. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was introduced in 2007 to standardize terminology used in reporting thyroid cytology [2,8]. The six categories used are supplemented by a list of diagnostic criteria. Each diagnostic category is linked to a certain risk of malignancy [8-10]. The objective of this study was to present the 5-year experience of the implementation of the Bethesda system for reporting thyroid cytopathology in Alpha Prolipsis Cytology Laboratories, a private medical laboratory located in Athens (Greece) and to present internal quality control measures that were implemented in order to increase reliability and traceability of cytological findings and reports.


The study included patients with palpable and non- palpable thyroid nodules referred to ALPHA PROLIPSIS Cytology Laboratories during a five-year period. The laboratory is certified according to ISO 15189: 2012 and employs three board certified cytopathologists with well-documented experience in thyroid cytology. Since May 2013, Alpha Prolipsis Cytology Laboratories started reporting all thyroid FNAs using the Bethesda system and followed the guidelines in the diagnostic manual “The Bethesda System for Reporting Thyroid Cytopathology. 617 cases of thyroid FNAs were examined. The patients were directly referred to Alpha Prolipsis Cytology Laboratories. All FNAs were performed under ultrasound guidance by a consultant radiologist. All aspirations (usually three or four passes per lesion) were performed under ultrasound guidance with 21-gauge needles attached to a 10-cm syringe for suction. On-site evaluation of the specimen adequacy was performed in all cases. In case of non-diagnostic sampling, immediate repeat of the FNA was mandated. Smears were made with both conventional and liquid cytology methods and were stained with the Papanicolaou and MGG techniques. All slides were diagnosed simultaneously by two or three board certified cytopathologists. All cytopathologists used TBSRTC terminology and adhered to its diagnostic criteria. Whenever diagnostic challenging cases were encountered, the final diagnosis was made after teleconsultation with an expert colleague with well-known experience in the field. Whenever thyroidectomy was performed on the basis of FNA results or other clinical criteria, such as a multinodular lesion, nodule size or a lack of response to treatment and, in some cases, on the patient’s decision because of a reluctance for periodic follow up, histological reports were methodically collected, reviewed and compared with initial cytological diagnoses. Malignancy rates for each TBSRTC category were calculated. The sensitivity and specificity of cytology for a histological diagnosis of malignancy was assessed. Statistical processing was performed with the software package IBM SPSS Statistics v.19 (IBM Corporation, Armonk, NY, USA).


256 (43.6%) male and 331 (56.4%) female patients with a median age of 43.9 years (range, 14-82 years) and a median size of aspirated nodules of 1.6 cm were included in our study. A total of 587 patients underwent 617 FNAs during the study period. The incidence of each Bethesda category is summarized in (Table 1). 533 FNAs (86.3%) were Category II (benign), 45 (7.2%) were Category III (AUS), 4 (0.6%) were Category IV, 28 (4.5%) were Category V (suspicious for malignancy) and 7 (1.1%) were Category VI (malignant). Of the 617 thyroid nodules from 587 patients who underwent FNA, thyroidectomy was performed to 146 (24.9%) patients, all of whom had histopathology available for review. This comprised 75/533 (14%) Category II cases, 32/45 (71.1%) Category III cases, 4/4 (100%) Category IV cases, 28/28 (100%) Category V cases, and 7/7 (100%) Category VI cases. The final histopathological diagnoses of cases in each category are summarized in (Table 2). Malignancy was diagnosed in 41 cases yielding an overall rate of malignancy of 6 % (37/617 nodules and 41/587 patients). Of the 533 nodules diagnosed as Bethesda II (benign), 4 nodules were found to be malignant, yielding a malignancy rate of 5.3 % (4/75) for those undergoing thyroidectomy, which represented 1.3% of the total number of Category II nodules. Of the 45 nodules diagnosed as Bethesda III (AUS/FLUS), 32 were followed up with thyroidectomy and malignancy was histologically confirmed in 5 cases with an estimated risk of malignancy of 11%. There were 4 Bethesda IV nodules (Follicular neoplasm/SFN) which underwent surgery and malignancy was identified in 1 case (25%). There were 28 Bethesda V nodules (suspicious for malignancy), all of which underwent surgery and 23 (82.1%) were confirmed to be carcinomas, 21 papillary carcinomas and 2 medullary carcinomas. Finally, there were 7 Bethesda VI nodules (malignant), all of which underwent surgery and all (100%) were histologically confirmed (5 papillary carcinomas, 1 medullary carcinoma and 1 primary lymphoma). The TBSRTC assigns a risk of malignancy for each diagnostic category. The estimated risk of malignancy in each TBSRTC category according to our study’s results is summarized in Table 3.