Thyroid Nodules with Atypia or Follicular Lesions of Undetermined Significance (AUS/FLUS): Analysis of Variables Associated with Outcome

Background: The Bethesda System for Reporting Thyroid Cytopathology is one of the main classification systems for thyroid nodules. It expects that 7% of all fine needle aspiration biopsies will be reported as atypia or follicular lesions of undetermined significance, and 5-15% of these undetermined nodules are malignant. Our study is a retrospective analysis of variables that may be associated with outcome in patients with indeterminate thyroid nodules. Materials and Methods: Patients who underwent thyroidectomy in our institution between 2010 and 2014 were retrieved from the institutional records database. Patient demographics and medical histories were recorded. All ultrasonography reports were examined for nodule features and biochemical blood levels, hormone levels and complete blood counts were recorded. Results: A total of 103 patient cytopathology reports were regarded as belonging to the undetermined category. Some 35% of patients had malignant nodules. Median preoperative red cell distribution width (RDW) level was 13.6 inthe benign group, while it was 14.3 in patients with malignancy, demonstrating a significant correlation (p=0.003). Only calcification presence was significantly different between benign and malignant groups on ultrasonography (p=0.034). Conclusions: Ultrasonography is one of the primary tools for this matter. RDW levels may become another promising tool to predict malignancy.