LAUSR

Simple Summary PTEN mutation is an extremely rare mutation in thyroid nodules with no clear prognostic indicators. In this multicenter study of 16 PTEN-mutated thyroid nodules, we found that 37.5% of the nodules were malignant. Aggressive features were present in 33.33% of the malignant tumours. We hypothesize that with time, PTEN-mutated thyroid nodules can acquire high allele frequencies (AFs) and widespread copy number alterations (CNAs), which might be aggravating the effects of PTEN mutations. Abstract While some studies suggest that PTEN mutations correlate with a low-risk phenotype in pediatric thyroid nodules, the relationship between the mutation and malignancy in the adult populations is abstruse. This study investigated whether PTEN mutations result in thyroid malignancy, and whether these malignancies are aggressive. This multicenter study involved 316 patients who underwent preoperative molecular testing, and subsequent lobectomy or total thyroidectomy at two quaternary care hospitals. A four-year retrospective review was performed on the 16 charts of patients that opted for surgery following a positive PTEN mutation on molecular testing results from January 2018 to December 2021. Of the total 16 patients, 37.5% (n = 6) had malignant tumours, 18.75% (n = 3) had non-invasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTPs), and 43.75% (n = 7) had benign disease. Aggressive features were detected in 33.33% of the malignant tumours. Malignant tumours were found to have a statistically significant higher allele frequency (AF). The aggressive nodules were all poorly differentiated thyroid carcinomas (PDTCs) with copy number alterations (CNAs) and the highest AFs.