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Subclassification of the Bethesda Category III (AUS/FLUS): A study of thyroid FNA cytology based on ThinPrep slides from the National Cancer Center in China
Author(s) -
Zhao Huan,
Guo HuiQin,
Zhao LinLin,
Cao Jian,
Sun Yue,
Wang Cong,
Zhang ZhiHui
Publication year - 2021
Publication title -
cancer cytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.29
H-Index - 57
eISSN - 1934-6638
pISSN - 1934-662X
DOI - 10.1002/cncy.22417
Subject(s) - medicine , atypia , cytology , thyroid , gynecology , malignancy , cytopathology , pathology
Background The atypia of an undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) category in the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is a heterogeneous category, which includes various cell patterns. The subclassification of AUS/FLUS was suggested in the 2017 TBSRTC. However, the risk of malignancy (ROM) associated with different subgroups remains unresolved. Herein, AUS/FLUS aspirates were subclassified, from which the ROM of each subgroup was determined. Methods All cases undergoing fine‐needle aspiration (FNA) from July 2013 to December 2018 were reviewed. Of 12,913 thyroid FNAs, 1053 (8.2%) were AUS/FLUS. The slides of 222 patients with AUS/FLUS with surgical follow‐up were reviewed and subclassified according to the recommendations of the 2017 TBSRTC. There were 195 aspirates consistently diagnosed as AUS/FLUS and subclassified as cytologic atypia 1 (AUS‐C1); cytologic atypia 2 (AUS‐C2); architectural atypia (AUS‐A); cytologic and architectural atypia (AUS‐C&A); Hürthle cell aspirates (AUS‐H); atypia, not otherwise specified (AUS‐NOS); and atypical lymphoid cells, rule out lymphoma (AUS‐L). Results Malignancy was identified in 83.3% (185 of 222) of the AUS/FLUS nodules. The AUS‐C1 group was the most common (62.1%), followed by the AUS‐C&A (12.8%), AUS‐C2 (10.8%), AUS‐H (6.7%), AUS‐NOS (5.6%), AUS‐L (1.5%), and AUS‐A (0.5%) groups. AUS‐C1 had the highest ROM (92.6%) among the groups and varied significantly from that of the AUS‐C&A ( P = .171), AUS‐C2 ( P = .001), AUS‐H ( P = .001), and AUS‐NOS ( P < .001) groups. Conclusions As a heterogeneous category of TBSRTC, the ROM for AUS/FLUS varies greatly among medical centers. Subclassification of AUS/FLUS might be helpful in identifying nodules with a high ROM in this category and improving the management of such nodules.