Here, we show that HPV-associated SNSCC shares mutational patterns found in HPV-associated cervical and head and neck squamous cell carcinoma, including lack of TP53 mutations, hotspot mutations in PI3K and FGFR3, enrichment of APOBEC mutagenesis, viral integration at known hotspots, and frequent epigenetic regulator alterations. This evidence concerns the gene PIK3CA and head and neck squamous cell carcinoma.