A likely explanations for the strong PDGFR phosphorylation in KSHV-negative tumors could be the increased PDGFB ligand expression as well as the occurrence of oncogenic mutations that convey constitutive signaling, like those found in other PDGFRA-driven sarcomas such as GIST [27, 28]. This evidence concerns the gene PDGFRA and gastrointestinal stromal tumor.