ALK-1 positivity serves as supportive evidence, while positive expression of SMA, MSA, and Vimentin provides essential diagnostic criteria, facilitating differentiation from other tumors originating from fibroblasts or smooth muscle cells, such as solitary fibrous tumor, nodular fasciitis, and malignant peripheral nerve sheath tumor (15, 17). This evidence concerns the gene TPO and malignant peripheral nerve sheath tumor.