Outcomes of the Bethesda system for reporting thyroid cytopathology: Real-life experience

Objective The 2017 revised Bethesda System for Reporting Thyroid Cytopathology (BSRTC) included new malignancy rates for each category as well as new management recommendations. Here, we evaluate the malignancy rate and test performance for BSRTC categories in a middle-sized institution outside the United States (US). Design Retrospective single centre case series with chart review. Patients All patients who underwent thyroid surgery with a preoperative BSRTC between the years 2010 and 2018 at our institution. Measurements In order to assess the malignancy rate for each BSRTC, all medical records were reviewed to collect demographics, nodule's size, BSRTC and final pathology. Results Three hundred and sixty-four patients were included, with an overall malignancy rate of 34.3%. The malignancy rate for BSRTC categories I-VI was as follows: 13.3%, 5.1%, 25.0%, 24.4%, 91.3% and 95.2%, respectively. The most sensitive test was when BSRTC III-VI were evaluated (91%). Overall best performance (sensitivity, specificity, PPV, NPV and accuracy) was obtained when BSRTC V-VI were grouped together with a substantial decrease when adding BSRTC III-IV (90%, 97%, 94%, 95%, 95% vs, respectively, 91%, 73%, 62%, 95%, 79%, respectively). Conclusions Despite differences from the reported 2017 BSRTC malignancy rates, we demonstrated that the revised 2017 BSRTC management recommendations for thyroid nodules are also valid in smaller non-US centre, supporting its use globally.

Automated summary

This study evaluated the malignancy rate and test performance for BSRTC categories in a middle-sized institution outside the US, finding the highest malignancy rate in BSRTC III-VI. The best overall performance was achieved when grouping BSRTC V-VI together, with a substantial decrease in performance when adding BSRTC III-IV. Despite differences from reported 2017 BSRTC malignancy rates, the study supported the validity of the revised 2017 BSRTC management recommendations for thyroid nodules in smaller non-US centers.