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

NTRK-rearranged mesenchymal tumour with epithelioid features: expanding the morphological spectrum of NTRK-fused neoplasms Thus, we aim to report a case with such features, hoping to raise awareness of the possible morphological variations of I NTRK i -rearranged mesenchymal neoplasms and, ultimately, broaden treatment opportunities for patients with locally advanced and unresectable or metastatic sarcomas. Neurotrophic tropomyosin receptor kinase ( I NTRK i ) fusion positive neoplasms were first identified in colorectal carcinoma almost 40 years ago.1 The availability of tyrosine kinase inhibitors specifically targeting receptors encoded by I NTRK i 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.2 In this context, the identification of morphological patterns that should lead to prompt assessment of I NTRK i rearrangements may aid the pathologist to improve detection of patients who might benefit from targeted therapy. Despite being most frequently found in spindle cell neoplasms pathologists must be aware that the histopathological features of such lesions may be broader than expected, so pan-Trk immunohistochemistry and/or I NTRK i molecular testing should be performed in all metastatic or locally advanced tumours irrespective of morphologic appearance in order to identify I NTRK i rearrangements not previously suspected. [Extracted from the article]