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

Abstract

IntroductionThyroid swelling is common problem among South Asian women. Although benign nodules far outnumber cancerous lesions, the risk of malignancy needs to be evaluated preoperatively for which fine needle aspiration cytology (FNAC) is widely used. Bethesda system for reporting thyroid cytopathology (BSRTC) was introduced to streamline the reporting of thyroid aspirates. We aimed to evaluate the disease spectrum of thyroid cytopathology and correlation of BSRTC with final histopathology in our setup.MethodsThe study was conducted at Histopathology department of Liaquat National Hospital, Karachi, involving 528 patients with thyroid swelling who underwent FNAC. Out of these 528 cases, 61 patients subsequently underwent surgical excision. Results of final histopathology were correlated with cytologic diagnosis.ResultsMean age of the patients included in the study was 39.7 ± 13(14–84) and male to female ratio was 1:3.6. Out of total 528 cases, 403 cases were diagnosed as benign (Bethesda 2) and 67 were Bethesda 3 (follicular lesion of undetermined significance, FLUS) while 22 cases were categorized as either malignant or suspicious for malignancy (Bethesda 6 and 5). Histopathologic correlation was done in 61 cases. For Bethesda 5 and 6 categories, 100% concordance was found, however for Bethesda 2 category, 5 out of 45 cases were found to have malignant diagnosis on final histopathology. The incidence of malignancy in Bethesda categories 2 through 4 were 11.1%, 33.4%, 25%, 100% and 100% respectively. Overall accuracy of FNA cytology was 80.3% with 64.3% sensitivity and 85.1% specificity.ConclusionOur study validated the accuracy of BSRTC in our setup. Therefore we recommend routine use of BSRTC for reporting thyroid cytopathology for initial workup of patients with thyroid nodule. However, risk of malignancy was found to be significantly high in Bethesda 3 category to warrant further workup including ultrasound/thyroid scan in addition to repeat FNAC.

Review of a single institution's fine needle aspiration results for thyroid nodules: Initial observations and lessons for the future

“…This group also accounted for 20.7% of all patients who underwent surgery. In our institution, B3 had a malignancy rate of 27% that was higher compared to some studies (5%‐17%), and lower compared to others (33%‐69%) . Due to the paucity of observations, we could not examine the correlation between malignancy rates in patients who underwent surgery alone vs those who underwent either a repeat FNA, follow‐up, or surgery but, in our opinion, this category should be treated with caution in light of the high malignancy rates reported …”

“…Most results were of category B2 and only 6% of category B5 or B6. We compared our results of FNA Bethesda classification prevalence and malignancy rates to those of studies published in different medical centres (Tables and ) …”

“…As stated, a more accurate identification of those patients needing a thyroidectomy is needed. Routine use of FNA resulted in a rise in malignancy rate of thyroid surgical specimens, yet the malignancy rate of B4 nodules remains low and with a wide variability at 14%‐50%, and an extremely low (26%) PPV. The management of patients with indeterminate result (B3 and B4) is not always straight forward and the clinician is faced with several options such as close observation, performing isotopic scans, genetic testing, repeat FNA, or recommendation for a diagnostic hemithyroidectomy.…”

Comparison of thyroid fine needle aspiration biopsy results before and after implementation of Bethesda classification

“…Accordingly, there are six thyroid cytology categories: non‐diagnostic, benign, atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), suspicious for malignancy and malignant . Studies show that the diagnostic accuracy of the Bethesda system in discriminating between benign and malignant nodules is high . However, there are a limited number of studies comparing the diagnostic value of the Bethesda system with previous classification systems.…”

The Bethesda System for Reporting Thyroid Fine Needle Aspirates.

“…endocrinologists, surgeons, radiologists and other health care providers; facilitate cytologichistologic correlation for thyroid diseases. 3 The atlas has six described diagnostics categories of lesions: Non diagnostic/Unsatisfactory, Benign, Atypical follicular lesion of undetermined significance (AFLUS), Suspicious for follicular neoplasm(SFN), Suspicious for malignancy(SM),and Malignant. Results:- Male Female 1 21-30 0 0 2 31-40 1 1 3 41-50 0 2 4 51-60 0 0…”