Pathogenic germline variants and somatic second hits were found in NF1, RB1, TP53, EXT2, and SDHC, in patients with a malignant peripheral nerve sheath tumor and GIST, leiomyosarcoma, leiomyosarcoma, secondary peripheral chondrosarcoma, and GIST, respectively. This evidence concerns the gene EXT2 and gastrointestinal stromal tumor.