[337] The Bethesda System for Reporting Thyroid Cytopathology: A Meta-Analysis

Massimo Bongiovanni, Alessandra Spitale, William C Faquin, Luca Mazzucchelli, Zubair W Baloch. Institute of Pathology, Locarno, Switzerland; Massachusetts General Hospital, Boston; University of Pennsylvania Medical Center, Philadelphia

Background: The Bethesda system for reporting thyroid cytopathology (TBSRTC) represents a further step toward standardization of reporting thyroid cytopathology and is now well established in the US. Through meta-analysis, we aim to investigate the validity of using the 6-tiered reporting system in US and European laboratories.
Design: All publications up to 01.09.2011 dealing with TBSRTC and with available histological follow-up were retrieved. To calculate sensitivity, specificity, diagnostic accuracy, we defined the true-positive as the follicular neoplasm+suspicious of malignancy+malignant FNA specimens that were histopathologically confirmed as malignant; the true-negative as the benign FNA specimens that were histopathologically confirmed as benign; the false-positive as the follicular neoplasm+suspicious of malignancy+malignant FNA specimens that were histopathologically confirmed as benign; and the false-negative as the benign FNA specimens that were histopathologically confirmed as malignant. Non-diagnostic and atypia of undetermined significance categories were excluded from the statistical calculation. Correlation between the six diagnostic categories were performed.
Results: The case cohort included a total of 24,445 thyroid FNAs, of which 5911 (24.2%) were followed-up by surgery and constituted the basis of the study. Cyto-histological correlations are showed in Table 1.

Cyto-histological correlations of TBSRTC
Cytological diagnosisAll FNAsAll FNAs with histological follow up  Benign histologyMalignant histology
 n (%)n% total (a)% category (b)n (%)n (%)
Non-Diagnostic3215 (13.1)5118.615.9427 (83.6)84 (14.4)
Benign14433 (59.0)139023.59.61344 (96.7)46 (3.3)
Atypia of undetermined significance (AUS)2433 (10.0)94916.139.0798 (84.1)151 (15.9)
Follicular neoplasm (FN)2399 (9.8)163127.668.01196 (73.3)435 (26.7)
Suspicious for Malignancy656 (2.7)4778.172.7114 (23.9)363 (76.1)
Malignant1309 (5.4)95316.172.812 (1.3)941 (98.7)
Total24445 (100)591110024.23891 (65.8)2020 (34.2)
(a) Percentage of the total 5911 operated cases; (b) Percentage of cases operated in each diagnostic category.

Sensibility, specificity and diagnostic accuracy were 97.4%, 50.4% and 69.3%, respectively. There were strong correlations noted between the diagnostic categories of the 6-tiered system and the histological follow-up data in predicting outcome.
Conclusions: TBSRTC represents a valuable reporting system based upon results of meta analysis showing high overall accuracy.
Category: Cytopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 48, Wednesday Afternoon

 

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