NTRK-Rearranged Spindle Cell Tumor with SPECC1L-NTRK3 Fusion in the Thoracic Spine: A Case Report

Neurotrophic Tyrosine Receptor Kinase (NTRK)-rearranged spindle cell tumors are a category of soft tissue tumors characterized by rearrangements of the NTRK gene that exhibit unique molecular genetics, morphological, and immunophenotypic features. The core feature of NTRK-rearranged tumors is rearrangement of the NTRK gene family (NTRK1, NTRK2, and NTRK3), often involving fusion with other genes, leading to abnormal tropomyosin receptor kinase (TRK) protein expression and activation. Herein, we report the first case of an NTRK spindle cell tumor with SPECC1L-NTRK3 fusion. This case highlights the significance of next-generation sequencing (NGS) for tumor diagnosis and targeted drug selection. After one month ofentrectinib therapy, the patient had considerable tumor shrinkage and symptom relief. For bone-derived NTRK-rearranged spindle cell sarcomas, entrectinib has demonstrated favorable therapeutic effects and can be considered priority treatment option.