Thyroid FNA Atypia of Undetermined Significance (AUS): Variability in Pathologist Reporting and Clinical Follow-Up.
Aparna Mahajan, Katherine Kasper, Xiaoqi Lin, Denise DeFrias, Charles Clevenger, Piotr Kulesza, Cord Sturgeon, Ritu Nayar. Northwestern University, Chicago, IL
Background: It is suggested that AUS comprise approximately 7% of thyroid FNA results; however post-Thyroid Bethesda publications show a wide inter institutional variation in AUS percentages. We are a medical center with board certified cytopathologists and a large thyroid FNA volume. We have a high institutional AUS rate; however we have used a 6-tired system for reporting thyroid FNA since 2001 and included cases limited by qualitative factors and cystic lesions in AUS. Implementation of Bethesda criteria for thyroid reporting and transition from our previous reporting pattern was inconsistent between pathologists in 2008/2009, prior to the publication of the Bethesda atlas in December 2009. This review was undertaken to measure the variability between our cytopathologists with the aim of improving AUS reporting and its outcomes.
Design: We queried our institutional database for FNA biopsies categorized as AUS between 6/2008 and 12/2009. 399 thyroid biopsies were identified. We reviewed the cytopathology reports, along with repeat FNA and surgical pathology follow up data.
|Total Thyroid FNA||154||545||343||158||586||519||2305|
|AUS # cases||13||48||120||14||106||98||399|
|AUS Rate (%)||8.4||8.8||35||8.9||18.1||18.9||17.3|
|REASON FOR AUS|
|% Hyperplasia vs. FN||54||73||62||36||64||64||64|
|% r/o Carcinoma/Lymphoma||8||2||3||7||18||3||7|
|REPEAT FNA* AFTER INITIAL AUS|
|Non Neoplastic %||67||69||85||50||50||32||54|
|Neoplastic (adenoma) %||0||25||15||25||29||49||31|
|Intradept. Consult %||15||21||8||0||6||2||7|