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Subclassification of atypical cells of undetermined significance in direct smears of fine-needle aspirations of the thyroid
Distinct patterns and associated risk of malignancy
Version of Record online: 25 MAR 2011
Copyright © 2011 American Cancer Society
Volume 119, Issue 5, pages 322–327, 25 October 2011
How to Cite
Renshaw, A. A. (2011), Subclassification of atypical cells of undetermined significance in direct smears of fine-needle aspirations of the thyroid. Cancer Cytopathology, 119: 322–327. doi: 10.1002/cncy.20154
- Issue online: 12 OCT 2011
- Version of Record online: 25 MAR 2011
- Manuscript Accepted: 22 FEB 2011
- Manuscript Revised: 14 FEB 2011
- Manuscript Received: 6 JAN 2011
- fine-needle aspiration;
Atypical cells of undetermined significance (AUS) in thyroid fine-needle aspirates (FNAs) may have poor interobserver agreement. Some authors have suggested that “atrophic” microfollicles should be diagnosed as benign. This laboratory sought to determine whether criteria for this diagnosis could be improved by subcategorizing cases into specific patterns, including the atrophic pattern, and determining their risk of malignancy.
A series of 7089 FNAs were reviewed and correlated with subsequent resection specimens. Cases of AUS were reviewed and subclassified.
Cases could be subcategorized into the following categories: 1) atypical, papillary carcinoma cannot be ruled out, 2) atypical, Hürthle cell neoplasm can not be ruled out, 3) cellular atrophic pattern, 4) scant atrophic pattern, and 5) cytologic atypia alone. Cytologic atypia alone (50%) and both atrophic patterns (21% and 34%) had a significant risk of malignancy.
The majority of AUS cases in thyroid FNA can be subcategorized into 5 different patterns, all with associated significant risk of malignancy. “Atrophic” microfollicles are a significant risk factor for malignancy and should not be diagnosed as benign on the basis of lack of cytologic atypia. Cancer (Cancer Cytopathol) 2011;. © 2011 American Cancer Society.