Several authors have underlined the limits of morphological analysis mostly in the diagnosis of follicular neoplasms (FN). The application of ancillary techniques, including immunocytochemistry (ICC) and molecular testing, contributes to a better definition of the risk of malignancy (ROM) and management of FN. According to literature, the application of models, including the evaluation of ICC, somatic mutations (ie, BRAFV600E ), micro RNA analysis is proposed for FNs. This study discusses the validation of a diagnostic algorithm in FN with a special focus on the role of morphology then followed by ancillary techniques.From June 2014 to January 2016, we enrolled 37 FNs with histological follow-up. In the same reference period, 20 benign nodules and 20 positive for malignancy were selected as control. ICC, BRAFV600E mutation and miR-375 were carried out on LBC.The 37 FNs included 14 atypia of undetermined significance/follicular lesion of undetermined significance and 23 FN. Specifically, atypia of undetermined significance/follicular lesion of undetermined significance resulted in three goitres, 10 follicular adenomas and one NIFTP whereas FN/suspicious for FN by seven follicular adenomas and 16 malignancies (nine non-invasive follicular thyroid neoplasms with papillary-like nuclear features, two invasive follicular variant of papillary thyroid carcinoma [PTC] and five PTC). The 20 positive for malignancy samples included two invasive follicular variant of PTC, 16 PTCs and two medullary carcinomas. The morphological features of BRAFV600E mutation (nuclear features of PTC and moderate/abundant eosinophilic cytoplasms) were associated with 100% ROM. In the wild type cases, ROM was 83.3% in presence of a concordant positive ICC panel whilst significantly lower (10.5%) in a negative concordant ICC. High expression values of MirR-375 provided 100% ROM.The adoption of an algorithm might represent the best choice for the correct diagnosis of FNs. The morphological detection of BRAFV600E represents the first step for the identification of malignant FNs. A significant reduction of unnecessary thyroidectomies is the goal of this application.

Introduction: Fine needle aspiration cytology (FNAC) plays a major role for the evaluation of thyroid nodules although 25% are follicular neoplasms (FN) with varying malignant risk. MicroRNA (miRNA) may reshape FNs as long as they are negative gene expression regulators involved in tumor development. Scant data explored miRNAs in thyroid FNAC. Method: From June 2014 to March 2015, 27 prospective FNs with histology were enrolled. Thirteen benign nodules (BN) and 20 positive for malignancy (PM) were selected as controls. FNs resulted at histology in 14 malignancies (3 Papillary thyroid carcinoma-PTC and 11 Follicular variant of PTC-FVPC) and 13 Follicular adenomas (FA). The 20 PMs included 2 FVPC, 16 PTC, 2 medullary carcinomas (MTC). MiRNAs were extracted from liquid based cytology (LBC), quantified by real time PCR, analyzed for 5 miRNAs (10b, 92a, 221, 222 and 375). Results: Only MiR-375 was over-expressed in the FNs and PMs diagnosed as thyroid carcinoma. A cut-off of 12 miR-375/miR-U6 relative ratio recognized 100% benign nodules regardless of categories and 95% PMs. Specifically in each FNAC category, FVPCs and PTCs did not show any difference whilst the highest expression was in MTCs. For miR-375, we reported 97.1% sensitivity, 100% specificity, 96.3% NPV, 98.3% diagnostic accuracy. Conclusions: LBC is suitable for miRNAs evaluation. MiR-375, over-expressed in all malignant FNs and 95% PMs, may represent a valid marker in ruling out BNs and supporting PTCs/FVPCs.