Atypia of Undetermined Significance: The Thyroid FNA Experience at University Hospital in San Antonio
Komal Arora, Teresa Duran, Phillip Valente, Maria Luisa Policarpio-Nicolas. University of Texas Health Science Centre, San Antonio, TX
Background: According to the recently proposed Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), the category of Atypia of Undetermined Significance (AUS) is reserved for specimens that contain cells with architectural and/or nuclear atypia insufficient to be classified as suspicious or malignant but the atypia cannot be confidently called benign. The recommendation is to use this category as a last resort and limit its use to approximately 7% or fewer of all thyroid fine needle aspirations (FNA). Since its publication in 2009, several institutes have published different percentages of reporting AUS. Also the follow up and outcome data in this category is limited. The objective of this study was to report our experience with the AUS category, to correlate these cases with the results of repeat cytology or surgical resection and to evaluate whether a repeat FNA versus surgical resection as follow-up would be a better option.
Design: A computerized search for all thyroid FNAs was performed from January 2008 to September 2011. For the FNA cases identified from Jan 2008 to December 2009, three cytopathologists who were blinded to the original diagnosis, re-classified the diagnosis using the TBSRTC. Starting January 2010 up to present, our institution implemented the TBSRTC. All cases which fell under the AUS category were selected and correlated with follow-up cytology or surgical specimen.
Results: Of a total of 985 thyroid FNAs reported, 86 (8%) had a diagnosis of AUS. Only 13/86 (15%) had follow-up repeat cytology (non-diagnostic 2, benign 8, AUS 2, malignant 1). Forty cases (46%) had surgical follow-up with the following results: Benign 32, Follicular lesion of uncertain malignant behavior 1, Follicular carcinoma 1, Papillary Carcinoma 6.
Conclusions: The proposed Bethesda algorithm for clinical follow-up of patient with an initial diagnosis of AUS is repeat FNA within 3-6 months, preferably ultrasound guided, and subsequent surgical resection if the follow-up FNA is AUS or worse. However, compressive symptoms or worrisome ultrasound findings frequently led to resection in lieu of repeat FNA. Given that 61% had a benign diagnosis on repeat FNA and 80% had a benign diagnosis on surgical resection, a repeat FNA is a reasonable option as opposed to surgical resection, which carries with it, associated morbidity.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 61, Wednesday Afternoon