Incidence, Clinical Characteristics, and Histopathological Results of Atypia of Undermined Significance in a Tertiary Center in UAE

Introduction: Bethesda classification of thyroid nodules cytology is an agreed upon method of classifying thyroid nodules according to risk of malignancy. Among them, Bethesda class III (Atypia of Undetermined Significance, AUS) has been a topic of great controversy. The reported estimated risk of malignancy associated with it varies in different studies. Our study investigates the associated incidence of malignancy in a single tertiary center in UAE. Methodology: Data were retrospectively collected over a 10-year period from January 2009 till December 2018 for cytology diagnosis of AUS. Patient charts were reviewed for method of management. Surgical and histopathology records were reviewed to compare findings on cytology versus histopathology. Results: A total of 180 cases were diagnosed Bethesda III (AUS) with a mean age of 45.09 ± 14.7 years. One hundred cases (55.6%) of them underwent surgical resection, and histopathological diagnosis was obtained. Among the operated cases, 46 were benign and 54 were malignant. Papillary thyroid cancer was the most common malignancy, seen in 39 (72.2%) of cases, and follicular cancer was the second most common, seen in 13 (24.1%) cases. Conclusion: The findings highlighted in our study suggest a higher incidence of malignancy in Bethesda III category than previously reported. It also puts in question the utility and benefit behind keeping a time gap and repeating FNA as previously recommended.