STRN-NTRK3-rearranged Mesenchymal Tumor of the Uterus Expanding the Morphologic Spectrum of Tumors With NTRK Fusions
Abstract
We have followed with great interest several recent reports published mainly in this journal on NTRK-rearranged mesenchymal tumors. The largest series by Davis and colleagues focused on NTRK-rearranged pediatric mesenchymal tumors.
Although the studied tumors showed certain variation in histologic appearances, all lesions manifested patterns previously reported in infantile fibrosarcoma.1 Tumors with lipofibromatosis-like morphology and S100-protein and CD34 co-expression harboring NTRK1 fusions were reported by Agaram et al,2 and potentially related tumors with NTRK1/2 fusions by Suurmeijer et al.3 In 2 other publications, very similar tumors with fibrosarcoma-like morphology were presented. In the first one, a soft tissue tumor with STRN3 (exon 3)-NTRK3 (exon 14) fusion along with a bone tumor harboring STRN (exon 3)-NTRK3 (exon 14) rearrangement was described.
Both cases showed diffuse pan-TRK and CD34 immunostaining, whereas S100 protein was negative.4 In the second article, 4 additional cases with RBPMS-NTRK3 and various NTRK1 fusions were reported. Apart from diffuse pan-TRK positivity, the neoplasms showed focal S100 protein expression but were negative for CD34 staining.
Of note, the tumors involved the uterine cervix (n=3) and corpus (n=1) and were thus the first NTRK-rearranged tumors ever reported in this location.5