With all the genomic data generated, an independent pathologist analyzed the hematoxylin/eosin staining of the primary tumors not validated as classic MPNSTs (Fig. S3), confirming NF1‐09 as a high‐grade MPNST, SP‐01 as a melanoma, SP‐05 as an NTRK‐associated spindle cell sarcoma, and SP‐06 remained unclassifiable. Here, TFF2 is linked to spindle cell sarcoma.