[391] The Impact of Using the Bethesda System for Reporting Thyroid Cytology Diagnostic Criteria for the AUS/FLUS Category

Beatrice Lee, Brian Smola, Xin Jing. University of Michigan Health System, Ann Arbor, MI

Background: AUS/FLUS has been a problematic diagnostic category due to it's predictive uncertainty for neoplasm or malignancy. To address terminology and other issues related to AUS/FLUS interpretation, the Bethesda System for Reporting Thyroid Cytology (BSRTC) refines definition and provides specific diagnostic criteria for the AUS/FLUS category. Our institution has implemented BSRTC since January 2011. The goal of this study was to review our institutional experience in regard to follow-up of thyroid nodules interpreted as AUS/FLUS using BSRTC diagnostic criteria.
Design: A SNOMED search of the electronic pathology in our institution for the period of 01/2011 to 06/2012 was conducted to retrieve thyroid aspirates previously interpreted as AUS/FLUS using the BSRTC diagnostic criteria. Information including specimen preparation method, names of the individual reviewers who initially assessed the specimens, availability of repeat fine needle aspiration and/or surgical intervention along with the corresponding cytologic and/or histologic diagnosis was collected. Cytology-histology concordance was evaluated for aspirates with surgical follow-up.
Results: 1. A total of 120 aspirates were retrieved. The aspirates were prepared as conventional smears (n=111) or ThinPrep (n=9).
2. A repeat fine needle aspiration was performed in 12.5% (15/120) of the AUS/FLUS cases. Among which, 4 cases remained as AUS/FLUS, 9 and 2 cases were re-categorized as benign and suspicious for neoplasm, respectively.
3. Surgical follow-up was available in 42.5% (51/120) of AUS/FLUS cases. Surgical interventions were performed following the initial and repeat AUS/FLUS interpretation in 94.1% (48/51) and 5.9% (3/51) of the surgically managed cases, respectively.
4. The follow-up histology revealed 27.5% (14/51) conventional papillary thyroid carcinoma, 23.5% (12/51) follicular adenoma and 49% (25/51) non-neoplastic nodules (nodular hyperplasia or lymphocytic thyroiditis).
5. The aspirates were originally evaluated by 8 individual cytopathologists with experience ranging from junior to senior level. The presence of neoplasia/malignancy in follow-up surgical specimens does not correlate with the level of the individual reviewer's experience.
Conclusions: In comparison to our previously reported data showing adenoma in 14.9% and carcinoma in 9.2% of the surgically managed AUS/FLUS cases, the current study demonstrates that adhering to the BSRTC diagnostic criteria yields a more reliable prediction of histology-proven follicular adenoma (23.5%) and malignancy (27.5%) for the AUS/FLUS category.
Category: Cytopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 95, Tuesday Afternoon

 

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