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 family (NTRK1, NTRK2, and NTRK3), which leads to distinct molecular genetics, morphological, and immunophenotypic characteristics. The central feature of these tumors is the fusion of NTRK genes with other genes, resulting in abnormal expression and activation of tropomyosin receptor kinase proteins.In this report, we present the first documented case of an NTRK spindle cell tumor with SPECC1L-NTRK3 fusion located in the thoracic spine. This case underscores the diagnostic and therapeutic importance of next-generation sequencing in identifying tumor-specific genetic alterations and selecting targeted therapies. Following 1 month of entrectinib treatment, the patient experienced considerable tumor shrinkage and symptomatic improvement. For bone-derived NTRK-rearranged spindle cell sarcomas, entrectinib shows promising therapeutic efficacy and should be considered a preferred treatment option.