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.
|Cytological diagnosis||All FNAs||All FNAs with histological follow up||Benign histology||Malignant histology|
|n (%)||n||% total (a)||% category (b)||n (%)||n (%)|
|Non-Diagnostic||3215 (13.1)||511||8.6||15.9||427 (83.6)||84 (14.4)|
|Benign||14433 (59.0)||1390||23.5||9.6||1344 (96.7)||46 (3.3)|
|Atypia of undetermined significance (AUS)||2433 (10.0)||949||16.1||39.0||798 (84.1)||151 (15.9)|
|Follicular neoplasm (FN)||2399 (9.8)||1631||27.6||68.0||1196 (73.3)||435 (26.7)|
|Suspicious for Malignancy||656 (2.7)||477||8.1||72.7||114 (23.9)||363 (76.1)|
|Malignant||1309 (5.4)||953||16.1||72.8||12 (1.3)||941 (98.7)|
|Total||24445 (100)||5911||100||24.2||3891 (65.8)||2020 (34.2)|