In our patient, the immunohistochemical profile was classic for leiomyosarcoma, with strong positivity for SMA, desmin, vimentin, and caldesmon, while negative for epithelial markers (cytokeratins), gastrointestinal stromal tumor markers (CD117, DOG-1), and other mesenchymal tumor markers (STAT6, SATB2). The gene discussed is SMN1; the disease is mesenchymal cell neoplasm.