Prospective evaluation of impact of using the Bethesda System for Reporting Thyroid Cytopathology: an institutional experience

Introduction The Bethesda System for Reporting Thyroid Cytology (BSRTC) refines the definition of and provides specific diagnostic criteria for fine-needle aspiration (FNA) assessment of thyroid lesions. This study was conducted to prospectively evaluate the diagnostic and clinical impact of using BSRTC for management of thyroid lesions and to compare diagnostic performance of post-BSRTC period with that of pre-BSRTC period. Materials and methods The study included FNA specimens obtained in our institution 2.5 years prior to and 2.5 years after implementing BSRTC. Nondiagnostic rate, distribution of the diagnostic categories, rate of surgical follow-up, cytohistologic concordant rate, and risk of malignancy were calculated and compared between pre- and post-BSRTC periods. Results In comparison to the pre-BSRTC period, the post-BSRTC period generated a lower nondiagnostic rate (19.9% versus 15.8%), a greater proportion of benign (65.3% versus 69.2%) and atypia of undetermined significance or follicular lesion of undetermined significance (4.4% versus 7.4%) in contrast with a decreased proportion of follicular neoplasm or suspicious for follicular neoplasm categories (5.6% versus 2.2%). Rate of surgical follow-up decreased for benign (13.8% versus 7.6%) and atypia of undetermined significance or follicular lesion of undetermined significance (61.5% versus 42.1%) categories, and overall surgical rate reduced (24.2% versus 18.1%). Implementation of BSRTC did not affect overall rate of cytohistologic concordance (78.4% versus 80.5%) or the overall rate of histologically proven malignancy (30.6 versus 36.9%), whereas the individual cytohistologic concordant rate and the malignant rate for each of the diagnostic categories did not differ between pre- and post-BSRTC. Conclusions The implementation of BSRTC resulted in a decreased overall surgical rate, particularly for benign and follicular lesion of undetermined significance categories, without affecting overall cytohistologic concordance and rate of malignancy.