N. Yepuri1, R. Naous2, R. Acharya3, M. Dhir1 1SUNY Upstate Medical University,General Surgery,Syracuse, NEW YORK, USA 2SUNY Upstate Medical University,Pathology,Syracuse, NEW YORK, USA 3SUNY Upstate Medical University,Medicine,Syracuse, NY, USA
Introduction: Indeterminate thyroid cytology is seen in approximately 25% of thyroid nodule fine needle aspirations (FNA) and 75% of these nodules are ultimately noted to be benign on final histology. The role of molecular tests is to reduce the number of unnecessary surgical procedures performed for benign nodules by improving the diagnostic discrimination between benign vs malignant nodules. Small single institution studies have previously reported that ThyGenX and ThyraMIR can reduce unnecessary surgeries; however more validation studies are needed. Aim of the current study was to determine if molecular testing using ThyGenX and ThyraMIR can alter surgical management in patients with Bethesda 3 and 4 nodules.
Methods: A single institution retrospective analysis of all Bethesda 3 (B3) and 4(B4) thyroid FNAs from 2013 to 2018 was performed after IRB approval. Patients with non-invasive follicular thyroid neoplasm with papillary like nuclear features (NIFTP) were grouped with malignant category as surgery is indicated in these patients.
Results:Of 413 FNAs, 25 (6 %) were diagnosed as B3 and 15 (4 %) were B4. The ThyGenX and ThyraMIR was obtained 4 B3 (16%) cases, and 5 of B4 (33%) cases. Eight patients with B3 underwent surgery and 4 were diagnosed with malignancy (1 PTC, 1 NIFTP, 1 FV-PTC, 1 – paraganglioma) resulting in an institutional malignancy rate of 50%. The remaining 4 patients were bening (2 hurthle cell change/adenoma, 2 nodular hyperplasia). Six patients with B4 underwent surgery and 3 were diagnosed with malignancy (1 FVPTC, 1 FTC, 1 PTC) resulting in an institutional malignancy rate of 50%. As the malignancy rate was similar for B3 and B4 molecular testing results were analyzed together for these nodule categories. Molecular testing results were available for 16 patients (6 B3, 10 B4)– 1 patient with B3 had positive PAX8-PPAR mutation while all others had negative testing. Only 2/16 patients underwent surgery. Patient with PAX8-PPAR B3 was found to have NIFTP whereas B4 patient who opted for surgery despite negative test result had benign final histology. Majority of the patients chose to continue surveillance based on clinical recommendations of negative molecular test.
Conclusion:In our small institutional cohort of B3 and B4 patients the malignancy rate was 50% based on FNA results. More data are needed to evaluate the role of molecular testing in B3 and B4 nodules are our institution.