[425] The Bethesda System for Reporting Thyroid Cytopathology: A Four-Year Single Academic Institution Experience

Constantine GA Theoharis, David C Chhieng, Diane Kowalski, Tobias Carling, Robert Udelsman, Adebowale J Adeniran. Yale University School of Medicine, New Haven, CT

Background: The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) is a standardized reporting system for classifying thyroid fine-needle aspiration results comprising of 6 diagnostic categories with unique risks of malignancy and recommendations for clinical management. Our objective was to report our past 4-year experience with the BSRTC, review its distribution and evaluate its efficiency based on the cytologic-histologic correlation.
Design: A total of 12,930 thyroid nodules undergoing FNA were examined at our institution between January 2008 and December 2011. All FNAs were classified prospectively into unsatisfactory, benign, FLUS/AUS (follicular lesions or atypia of undetermined significance), follicular neoplasm (FN), suspicious for malignancy, or positive for malignancy. The Cyto-histologic correlation was recorded.
Results: Table 1 summarizes the diagnostic frequencies.

4 Years of the BSRTC Diagnostic Frequencies (%)
 2008200920102011Total 2008-11
Non-Diagnostic11.1911.048.717.139.44
Negative73.5371.2873.0576.6673.75
FLUS/AUS4.274.367.105.825.14
FN5.305.604.213.114.50
Suspicious1.341.371.971.911.66
Positive5.366.354.965.385.51
Total (n)3,2083,0713,0433,60712,930
FLUS/AUS: Follicular Lesion of Undetermined Significance/Atypia of Undetermined Significance. FN: Follicular Neoplasm

Table 2 summarizes the 4-year cyto-histologic correlation.

4 Years Cytology-Histology Patient Correlation
2008-2011Cytology FNA Results      
HistologyNon-DiagnosticNegativeFLUS/AUSFNSuspiciousPositiveTotal
Malignant23.80%18.00%56.80%32.70%91.00%99.60%52.60%
Neoplastic10.40%7.70%15.00%41.30%2.40%0.00%11.70%
Non-neoplastic65.90%77.30%28.20%26.00%6.60%0.40%35.70%
Total Surgery Patients #(%)164 (13.4)621 (6.5)287 (43.2)400 (43.2)166 (77.6)561 (79.2)2,199 (17.0)
FLUS/AUS: Follicular Lesion of Undetermined Significance/Atypia of Undetermined Significance. FN: Follicular Neoplasm

The false positive rate for a malignant and suspicious diagnosis was 0.4% and 9.9%, respectively. The specificity of diagnosing malignant thyroid nodules was 97.7% whereas the specificity as a screening test for all neoplasms was 89.6%.
Conclusions: The BSRTC shows excellent specificity in diagnosing malignant nodules and in screening for neoplasms. Each diagnostic category conveys specific risks of malignancy, which offers guidance for clinical management. In addition, the frequency distribution of the individual diagnostic categories remained relatively stable over time.
Category: Cytopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 96, Tuesday Afternoon

 

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