Morphology combined with ancillary techniques: An algorithm approach for thyroid nodules

Abstract

Introduction 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, BRAF V 600E ), micro RNA analysis is proposed for FN s. 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 . Methods From June 2014 to January 2016, we enrolled 37 FN s with histological follow‐up. In the same reference period, 20 benign nodules and 20 positive for malignancy were selected as control. ICC , BRAF V 600E mutation and miR‐375 were carried out on LBC . Results The 37 FN s 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 adenoma s 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 sample s included two invasive follicular variant of PTC, 16 PTC s and two medullary carcinomas. The morphological features of BRAF V 600E 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 . Conclusions The adoption of an algorithm might represent the best choice for the correct diagnosis of FN s. The morphological detection of BRAF V 600E represents the first step for the identification of malignant FN s. A significant reduction of unnecessary thyroidectomies is the goal of this application.