NTRK1 and mesenchymal cell neoplasm: In our cohort, two NTRK3-fusion-positive tumors are described: one with an ETV6 fusion partner and one with RBPMS. The latter arose in the lung and showed only diffuse weak cytoplasmic pan-TRK staining, and an IHC pattern also demonstrated in mesenchymal tumors lacking NTRK-fusions.