NTRK-Rearranged Spindle Cell Neoplasm

**Semantic type:** Neoplastic Process

**Definition:** An emerging rare group of soft tissue tumors, usually characterized by a monomorphic spindle cell infiltrate, stromal hyalinization, and frequent coexpression of S100 and CD34 by immunohistochemistry. Most tumors harbor NTRK1 fusions with a variety of partners. Rare cases involving NTRK2 and NTRK3 fusions have also been reported. The tumors usually arise from the extremities, trunk, and head and neck area, and less often within body cavities.

**Synonyms:** - Lipofibromatosis-Like Neural Tumor - NTRK-Positive Tumor Resembling Peripheral Nerve Sheath Tumor - NTRK-Rearranged Mesenchymal Tumor - SCN-NTRK - Spindle Cell Neoplasm, NTRK-Rearranged