Reporting Thyroid FNA before and after Implementation of Bethesda System
Kathriel J Brister, Remmi S Singh, Helen H Wang. Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
Background: The Bethesda System for Reporting Thyroid Cytopathology was published in 2008, and was implemented at Beth Israel Deaconess Medical Center (BIDMC) in June 2010. Prior to this date, our diagnostic scheme was similar to the Bethesda System, except for the category of “Atypia/Follicular Lesion of Undetermined Significance” (AUS). Instead, we used the categories “Atypical (ATY),” “Suboptimal (SUB)” and “Indeterminate (IND)” to describe specimens that would later be classified as AUS. This study evaluates the impact of the Bethesda System on the rate and the positive predictive value (PPV) of the diagnostic categories at BIDMC.
Design: We performed a retrospective review of all thyroid FNAs during the time periods Jan 2006-Nov 2008 and June 2010-July 2011 (period 1 and 2, respectively) and identified 2355 and 1204 specimens, respectively. Each cytology report was categorized as shown in Table 1 below. All subsequent thyroidectomy specimens were identified (406 and 227 from period 1 and 2, respectively) and categorized as benign or malignant. PPV was determined for each cytologic category.
|Diagnostic Category||1st Period||2nd Period|
|% of total||PPV in %||% of total||PPV in %|
|SUB-benign, including cysts||21||15|
|SUB-Hürthle cell (HC) lesion or microfollicular lesion||2.5||17|
|SUB-papillary carcinoma (PC)||0.93||36|