The role of miRNAs in the evaluation of follicular thyroid neoplasms: an overview of literature.

MicroRNA (miRNA) deregulation has been frequently associated with different human cancers. Not only have miRNAs been involved in almost every cellular function but they have also been linked with a significant number of cancers including thyroid carcinomas. Specifically, thyroid tumors encompass several different miRNA profiles based on the histotypes. Furthermore, thyroid lesions with their broad spectrum of neoplasms (from benign to malignant entities) offer the possibility of studying and recognizing specific subsets of different up-and downregulated miRNAs in each different entity. To date, the majority of authors completed their evaluation mostly by including histologic samples of thyroid tumors. Nonetheless, in the last years, a few studies are focusing on the role of miRNA expression in thyroid fine-needle aspiration cytology (FNAC) regardless of the cytologic preparation, including liquid-based cytology. This growing interest is driven by the possible role of miRNAs in the malignant risk stratification, especially for the indeterminate categories of follicular neoplasms (FNs). In this review we overview the reliability of analyzing miRNAs on thyroid lesions, including those diagnosed as FNs, to identify whether their profiles are likely to distinguish benign from malignant lesions, providing a predictive molecular diagnosis on FNAC.