Detection of PTEN Mutations in Fine Needle Aspiration Biopsies of Indeterminate Thyroid Nodules: Impact on Diagnosis and Prognosis

Background: Data connecting PTEN mutations with thyroid cancer risk for indeterminate nodules remain limited due to the rare nature of these mutations. The aim of this study was to determine the relationship between PTEN mutations identified in cytologically indeterminate nodules and final pathology and clinical outcomes. Methods: This 8-year retrospective study includes adults with indeterminate thyroid nodules positive for a PTEN mutation and available correlative surgical histopathology. Results: Twenty-three patients with 24 total nodules met the inclusion criteria. The cytology specimens were characterized as Bethesda III (n = 19) and Bethesda IV (n = 5). Specific PTEN mutations detected are described in detail. Final histopathology included the following: benign (n = 18, 75.0%), papillary thyroid carcinoma (n = 3, 12.5%), follicular thyroid carcinoma (n = 2, 8.3%), and poorly differentiated thyroid carcinoma (n = 1, 4.2%). Conclusions: Together, our data suggest that PTEN mutations in indeterminate thyroid nodules result in a 25.0% risk of malignancy (Bethesda III: 16.7% and Bethesda IV: 60%).