Seven NTRK3-rearranged soft tissue spindle cell tumors other than classic IFS were retrieved from the consultation files of two of the authors (C.R.A., C.D.F.). The case selection for molecular investigation was based on the initial reported observations that the morphologic spectrum of kinase fusion-positive sarcomas includes tumors resembling fibrosarcomas (FSs) or MPNSTs. A large collection of these various morphologies was available in our consultation files from prior molecular studies, which were previously screened and lacked abnormalities in NTRK1/2, BRAF, and RAF1 genes.1 (link),3 (link) Clinical data, including age, gender, anatomic site, and gross features of tumors were retrieved from pathology reports. All tumors had been surgically removed and hematoxylin and eosin-stained slides from resection specimens were reviewed by two of us (A.S., C.R.A.). Tumors were graded according to the FNCLCC grading system. IHC for CD34, S100, SOX10, pan-TRK (TRK-ABC), and H3K27me3 was performed according to standardized procedures on automated platforms. Staining was performed on a Leica-Bond-3 (Leica, Buffalo Grove, Illinois) or a Ventana Benchmark (Ventana Medical Systems, Tucson, Arizona) automated immunostaining platform using a heat-based antigen retrieval method and high pH buffer.