To assess the sensitivity and specificity of the PTPN11 mutation in the screening of plasma to diagnose HS, we tested the plasma of 49 dogs with HS, 19 healthy dogs, 14 dogs with non-cancerous diseases, and 51 dogs with other cancers (multicentric lymphoma, OMM, soft tissue sarcoma, Langerhans cell sarcoma, nephroblastoma, hemangiosarcoma, and ocular melanoma) (Supplementary Table 1). This evidence concerns the gene PTPN11 and histiocytic sarcoma.