SAT571 When Two Is Too Few: Bethesda IV Pathology On Repeat Thyroid Fine Needle Aspiration

Disclosure: C.M. Godar: None. A.J. Spiro: None. M.K. Shakir: None. T.D. Hoang: None. Background: The 2015 American Thyroid Association Guidelines for Adult Patients with Thyroid Nodules provide a strong recommendation against routine ultrasound surveillance of thyroid nodules for which two benign fine needle aspiration (FNA) cytology results have been previously obtained. Strict adherence to these guidelines may hinder detection of malignancy, especially in large nodules where there is potential to miss heterogeneous pathology based on sampling technique. Clinical Case: A 36-year-old female was evaluated for surveillance of a large non-toxic multinodular goiter. Thyroid ultrasound demonstrated a dominant right thyroid nodule greater than 7 centimeters in size. The patient had undergone FNA of this nodule in 2014 and 2019 with Bethesda II (benign) cytopathology results. A chest x-ray showed tracheal deviation without evidence of narrowing. She noted a sensation of neck pressure without dysphagia or shortness of breath. She denied fatigue, heat or cold intolerance, hand tremor, or pretibial myxedema. She denied a family history of thyroid cancer or any history of neck irradiation. Due to new compressive symptoms a repeat FNA was performed. Three passes were performed with adequate samples, and the final FNA cytopathology demonstrated a Hurthle cell oncocytic-type follicular neoplasm with Bethesda IV classification. The sample was submitted for ThyGeNEXT(TM) and ThyraMIRv2(TM) molecular testing, which returned with NRAS q61R mutation of moderate-to-high risk of malignancy (65-75%). The patient was subsequently referred for total thyroidectomy with pending surgery date. Discussion: The current ATA guidelines offer a cost-effective surveillance strategy for the vast majority of patients with thyroid nodules. False negative FNA results are rare and are reported to occur in about 1% of cases(1). As in this vignette, it is reasonable to perform an additional FNA after two consecutive Bethesda II results in nodules with clinically significant growth, new compressive symptoms, or if there is concern for incomplete sampling in nodules of large size. During an FNA, care should be taken to gently move the needle at various angles to capture follicular cells from different areas within a nodule. Large nodules should be sampled via multiple, separate skin entry points when feasible. Judicious use of repeat FNA along with these sampling techniques may help to prevent under-diagnosis in nodules containing multifocal areas of heterogeneous pathology. Reference: 1) Durante C, Costante G, Lucisano G, Bruno R, Meringolo D, Paciaroni A, Puxeddu E, Torlontano M, Tumino S, Attard M, Lamartina L, Nicolucci A, Filetti S. 2015. The natural history of benign thyroid nodules. JAMA 313:926-935 Presentation: Saturday, June 17, 2023