The pathology and IHC results (Fig. 3) were consistent with poorly differentiated sarcoma, with a spindle cell pattern, high cellularity, moderate atypia, fibrillar and edematous stroma, a mitotic index of 8 per 2 mm, diffusely positive CD34, diffusely positive monoclonal H3K27me3, Sox10-, S100-, Desmin-, and Myogenin-, suggesting a possible diagnosis of MPNST, especially if there are clinical signs of NF1-type genetic comorbidity. This evidence concerns the gene SOX10 and malignant peripheral nerve sheath tumor.