'Suspicious for a follicular Neoplasm' before and after the bethesda system for reporting thyroid cytopathology: Impact of standardized terminology

Background: The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) standardized the terminology for indeterminate diagnoses, but the performance of the indeterminate categories before and after TBSRTC has not been compared. This study evaluates the 'suspicious for a follicular or Hürthle cell neoplasm' (SFN/HCN) category before and after the introduction of TBSRTC at a single institution and in a meta-analysis of the literature. Methods: A meta-analysis compiled findings from publications on SFN/HCN or similar diagnoses before and after the introduction of TBSRTC. The pathology database at our institution identified all SFN/HCN or similar diagnoses in the 8 years surrounding the introduction of TBSRTC, and those cases were correlated with the surgical follow-up. Results: In the meta-analysis, the fraction of cases called SFN/HCN or the equivalent increased from 6.1 to 7.4% (p = 0.0002); the surgical follow-up rate increased from 55 to 61% (p < 0.00001), and the histological malignancy rate among the cases that were resected increased from 22 to 28% (p = 0.03) after TBSRTC. In our institutional experience, the introduction of TBSRTC did not coincide with any significant changes. Conclusion: Standardized terminology clearly coincided with increases in follow-up and the malignancy rate of SFN/HCN. A change in the same statistics was not seen in our institutional experience.