Atypia of undetermined significance in thyroid fine needle aspiration cytology revisited

Background and objectives

Fine needle aspiration cytology (FNAC) is a cost-efficient technique for the management of thyroid nodules. Changes in the World Health Organization classification of thyroid tumors can influence reliability of cytology. The 2023 Bethesda System for Reporting Thyroid Cytopathology has adapted cytological nomenclature to these changes. The aim of this paper was to review the management of atypia of undetermined significance (AUS) in our institution.

Methods

Retrospective review of thyroid FNAC diagnosed with AUS in a single hospital between 2014 and 2022. We analyzed the management of patients and the risk of malignancy associated with AUS.

Results

AUS represented 7.5% of all thyroid FNAC diagnoses (273 patients). In 74.1% of the patients, FNAC was repeated, and 54.9% of the lesions were downgraded. Surgical resection of the nodule was performed in 38.2% of the patients, mostly after a repeat FNAC with upgrading. Ninety-one percent of the patients downgraded in the repeat FNAC did not undergo surgery. The risk of malignancy of the AUS category after repeat FNAC was 26.1%. AUS diagnosis was due to nuclear atypia in 32% of the patients, and we found a significant association between nuclear atypia and upgrading in repeat FNAC. Of the 96 patients who underwent surgery in our series, 42 had malignant lesions, including noninvasive follicular thyroid neoplasms with papillary-like features.

Conclusions

The clinical management of AUS patients includes repeat FNAC, which is strongly correlated with the risk of malignancy. Nuclear atypia seems to be more predictive of malignancy than architectural patterns.

Full text

The study was recently published in the Journal of Clinical and Translational Pathology.

Journal of Clinical and Translational Pathology (JCTP) is the official scientific journal of the Chinese American Pathologists Association (CAPA). It publishes high quality peer-reviewed original research, reviews, perspectives, commentaries, and letters that are pertinent to clinical and translational pathology, including but not limited to anatomic pathology and clinical pathology. Basic scientific research on pathogenesis of diseases as well as application of pathology-related diagnostic techniques or methodologies also fit the scope of the JCTP.

Follow us on X: @xiahepublishing

Follow us on LinkedIn:  Xia & He Publishing Inc.