NTRK-rearranged mesenchymal tumour with epithelioid features: expanding the morphological spectrum of NTRK-fused neoplasms

Neurotrophic tropomyosin receptor kinase (NTRK) fusion positive neoplasms were first identified in colorectal carcinoma almost 40 years ago . The availability of tyrosine kinase inhibitors specifically targeting receptors encoded by NTRK genes (Trk receptors), together with a considerable clinical response and favourable safety profile has sparked interest in improving the detection of such fusions in the clinical setting, including in sarcomas with unresectable/metastatic disease . In this context, the identification of morphological patterns that should lead to prompt assessment of NTRK rearrangements may aid the pathologist to improve detection of patients who might benefit from targeted therapy.