The tumor cells were negative for desmin, HHF35, HMB45, Melan A, MITF, c-kit, DOG1, cytokeratin AE1/AE3, h-caldesmon, STAT6, CD68, CD31, Factor 8, and ERG, making diagnoses of PEComa, GIST, SFT, and angiosarcoma unlikely. This evidence concerns the gene PECAM1 and angiosarcoma.