Thyroid cytology—nuclear versus architectural atypia within the “Atypia of undetermined significance/follicular lesion of undetermined significance” Bethesda category have significantly different rates of malignancy

Abstract

The disparity between malignancy risks within the Bethesda "atypical" category suggests that cytologic (nuclear) atypia is significantly more predictive of malignancy than architectural atypia. This supports the substratification of patients according to risk and a corresponding management approach within this category. A sonographic finding of irregular margins is also predictive for malignancy. Cancer Cytopathol 2017;125:245-256. © 2016 American Cancer Society.

Importance of cytological subclassification of thyroid nodules with Bethesda category III cytology (AUS/FLUS) into architectural atypia only and nuclear atypia: A prospective study

“…Nishino and Wang, compiling a series of retrospective studies, found malignancy in 55% of patients in subcategory NA versus 22% in subcategory AA. In subsequent studies, these rates were, respectively, 52.7% versus 6.8%, 51% versus 8.1%, 35% versus 10%, 65.8% versus 14.3%, and 36.8% versus 14.7% . To our knowledge, the only prospective study available showed malignancy in 41.3% of cases of subcategory NA and in 10.8% of subcategory AA …”

The impact of noninvasive follicular thyroid neoplasm with papillary‐like nuclear features on the rate of malignancy for atypia of undetermined significance subcategories

“…FNAs could be placed into this category for different cytologic characteristics ranging from limited nuclear atypia and focal architectural changes to Hürthle cells or even atypical lymphocytic aspirates . By subcategorizing AUS according to types of atypia, several studies have demonstrated differences in the ROM for better risk stratification . This approach has been adopted and is recommended by the new 2017 TBSRTC .…”

“…Gan et al from the National University Hospital in Singapore reported a series of 137 AUS nodules undergoing thyroidectomy. There were 37 malignant nodules, and 6 of them were FVPTC (5 as AUS‐N and 1 as AUS‐F).…”

“…TBSRTC has illustrated several scenarios for the diagnosis of AUS, and this highlights the heterogeneous nature of this category . Previous studies have demonstrated that subcategorizing AUS nodules on the basis of features such as nuclear atypia, a microfollicular pattern, and Hürthle cell predominance yields significant differences in the ROM on follow‐up . An editorial review has shown that atypia of undetermined significance with nuclear atypia (AUS‐N) has the highest ROM on resection (55%), and it is followed by atypia of undetermined significance, not otherwise specified (AUS‐NOS; 35%), atypia of undetermined significance with a microfollicular pattern (AUS‐F; 22%), and atypia of undetermined significance with Hürthle cells (AUS‐H; 6%) .…”

“…1 Previous studies have demonstrated that subcategorizing AUS nodules on the basis of features such as nuclear atypia, a microfollicular pattern, and H€ urthle cell predominance yields significant differences in the ROM on followup. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] An editorial review has shown that atypia of undetermined significance with nuclear atypia (AUS-N) has the highest ROM on resection (55%), and it is followed by atypia of undetermined significance, not otherwise specified (AUS-NOS; 35%), atypia of undetermined significance with a microfollicular pattern (AUS-F; 22%), and atypia of undetermined significance with H€ urthle cells (AUS-H; 6%). 22 Accordingly, the recently published 2017 TBSRTC recommends further subcategorization of an AUS diagnosis.…”