Total RNA, including miRNA, was isolated from FFPE VLS samples. miRNAseq analysis was performed on an Illumina NGS system NextSeq 500 and Illumina BaseSpace Sequence Hub (https://www.illumina.com) to measure miRNA abundance. A small RNA seq analysis conducted on six VLSca and five VLSfc samples revealed 163 differentially expressed miRNAs. Based on both the hierarchical clustering analysis and the PAM risk prediction analysis, the two cases (LIC19 and LIC20) in which invasive VSCCs were diagnosed a few years later, showed a high-risk expression profile similar to VLSca specimens with a concurrent invasive VSCC. [Extracted from the article]