[Receptor tyrosine kinase- fusions in paediatric spindle cell tumors]

Pediatric spindle cell tumors are rare and often difficult to diagnose due to a similar morphology and a non-specific immunohistochemical profile. Genetic characterization of these lesions has been constantly improving, which has led to the identification of new subgroups that were partly included in the WHO classification. Receptor tyrosine kinase fusions play a special role in these tumors and their verification has diagnostic relevance and can be an option for target-oriented therapies. In the case of pediatric spindle cell tumors, genetic fusions form especially with NTRK1‑3, ALK, RET, and ROS1. Overall, pediatric tumors with receptor tyrosine kinase fusions are predominantly low-grade tumors, which are often subdivided into the group of intermediate-malign tumors.