Digital Gene Expression Analysis on Cytology Smears Can Rule-out Malignancy in Follicular-Patterned Thyroid Tumors

Publication date: Available online 18 November 2019Source: The Journal of Molecular DiagnosticsAuthor(s): Elisabetta Macerola, Anello Marcello Poma, Agnese Proietti, Rossana Romani, Liborio Torregrossa, Clara Ugolini, Teresa Rago, Paolo Vitti, Fulvio BasoloPatients with indeterminate thyroid nodules (Bethesda III and IV) are often treated with diagnostic lobectomy, which in the majority of cases represent an overtreatment. A reliable rule-out molecular test could spare patients unnecessary surgery. Stained smears of 88 indeterminate thyroid nodules with histological diagnosis of follicular-patterned tumors were selected: 34 follicular adenomas (FA), 34 follicular variant papillary thyroid carcinomas (FVPTC), and 20 noninvasive follicular neoplasms with papillary-like nuclear features (NIFTP). The expression level of 126 genes was measured by digital counting. Mutation testing was performed for the main gene mutations and fusions. Performance of gene expression and mutation tests was calculated by ROC analysis. The gene expression model showed an area under the curve (AUC) of 88%, with 91% negative predictive value in FA and FVPTC only; part of NIFTPs were labeled as benign and part as malignant, thus the classifier performance worsened. Two FAs (5.9%), eight NIFTPs (40%), and 22 FVPTCs (64.7%) were mutation-positive. Mutation testing AUC was 79% in FA and FVPTC, and decreased by including NIFTPs. This gene expression–based test was feasible in thyroid stained smears, showed...
Source: The Journal of Molecular Diagnostics - Category: Pathology Source Type: research