Apart from MSI analysis, our targeted-NGS panel analysis of 136 sinonasal carcinoma and WES of the 10 patient-derived cell lines showed, as expected from previous studies [19,20,25], that EGFR exon 20 mutations (EGFRex20ins) are a hallmark of ISPs. This evidence concerns the gene EGFR and nasal cavity and paranasal sinus carcinoma.