NTRK1 and neoplasm: In the largest study conducted on NTRK fusions by Solomon et al. (6), including multiple detection assays across more than 33,000 cases of a wide range of tumour types, immunohistochemistry for pan-Trk staining demonstrated positivity for 1 of 5 Ewing sarcomas and 3 of 5 sarcomas with BCOR translocations, but no positivity for NTRK gene fusions was found by RNA sequencing.