NTRK1 and fibrosarcoma: The immunohistochemistry performed with pan-Trk antibody showed reactivity in 12/105 (11.4%) analyzed samples, but the molecular analysis showed positivity for ETV6-NTRK3 fusion in 2 cases only; therefore, we can confirm that NTRK gene fusions emerge in a only a small fraction (approximately 2%) in contradistinction to other rare paediatric neoplasms, including secretory carcinoma of the breast (15), congenital mesoblastic nephroma (16) and infantile fibrosarcoma (17) where NTRK fusion is characteristic and often disease defining.