NTRK3 and fibrosarcoma: The erythroblast transformation-specific (ETS) variant 6 (ETV6)-neurotrophic receptor kinase (NTRK3) fusion has been identified in glioblastoma, mammary secretory carcinoma, salivary gland mammary carcinoma, adult lung cancer, papillary thyroid cancer, and mesenchymal tumors including infantile fibrosarcoma, mesoblastic nephroma, IMT, and gastrointestinal stromal tumors [1, 2, 4–8].