MON-381 A Case of the Irregularly Bordered Thyroid nodule

Abstract Disclosure: A. Telesford: None. M. Shams: None. M. Nassiri: None. K. Peterkin: None. S. Mc Lean: None. Introduction:Thyroid nodules are a common incidental finding, with approximately 10-15% proving to be malignant. However, up to 30% of nodules remain indeterminate after FNA biopsy, making management a complex, shared medical decision. We present a case of a thyroid nodule with indeterminate cytology and intermediate-risk molecular findings, highlighting the challenges in clinical decision-making. Clinical Case: A 38-year-old Afro-Caribbean woman with a history of allergic rhinitis and PCOS presented with an asymptomatic thyroid nodule detected through self-palpation. She had no signs of thyroid dysfunction and was taking fluticasone, cetirizine, and drospirenone/ethinyl estradiol. Ultrasound revealed a 1.7 cm heterogeneous, hypoechoic nodule in the right thyroid lobe with concerning features, including microcalcifications and possible extrathyroidal extension, classified as TIRADS 5. FNA cytology was categorized as Bethesda III, indicating atypia of undetermined significance. Molecular testing identified an NRAS mutation with a 50% clonal mutation rate, suggesting an intermediate risk of malignancy.Laboratory studies showed elevated antithyroglobulin level(53.1 IU/mL,n <10 IU/mL) TSH, free T3, free T4, and TPO antibodies, were within normal limits,. Follow-up ultrasound showed a slight decrease in nodule size to 1.6 × 1.5 × 1.1 cm, with additional nodules noted. However, the TIRADS 4 nodule remained the primary concern. Given the molecular findings and irregular sonographic features, a right-sided transaxillary robotic thyroidectomy was performed. Pathology confirmed a 1.6 cm follicular adenoma without malignancy, though some peripheral irregularities were noted. The postoperative course was uncomplicated, with transient hoarseness, seroma, and neck stiffness, all resolving without intervention. Conclusion: This case highlights the challenges of managing thyroid nodules with indeterminate cytology and intermediate-risk molecular findings. Despite the benign final diagnosis, the decision to proceed with surgery was influenced by concerning ultrasound features and the molecular profile. With the increasing number of FNA biopsies performed, this case raises the question of whether a more conservative approach with serial imaging could have been an alternative. Additionally, the potential role of hormonal factors, such as OCP use and PCOS, in thyroid nodule development warrants further investigation. While the association between estrogen and thyroid nodule growth is not well-established, hormonal influences may impact thyroid function and nodule progression . Further research is needed to explore estrogen’s role in thyroid cell proliferation.This case underscores the importance of a multidisciplinary approach to thyroid nodule management, integrating clinical, molecular, and imaging findings to guide personalized treatment decisions. Presentation: Monday, July 14, 2025