NTRK-fusion associated sarcoma: Identification of two cases with a distinct perineurioma-like pattern

Abstract

Neurotrophic receptor tyrosine kinase (NTRK) gene fusions are oncogenic drivers found in a few rare tumours. However, NTRK rearrangements are being increasingly identified in a range of soft tissue neoplasms. Recognition of NTRK fusion-driven sarcomas is problematic, with a range of histological features reported. We present two cases of retroperitoneal NTRK-fusion associated sarcoma demonstrating a distinct perineurioma-like pattern and discuss features that should prompt immunohistochemical evaluation with pan-TRK, a surrogate marker of tumours harbouring NTRK fusions. Identification of these tumours is now critical since NTRK-rearranged tumours are one the few translocation-associated sarcomas amenable to highly effective targeted TRK inhibitor therapy.

Keywords

• Neurotrophic receptor tyrosine kinase (NTRK)
• Sarcoma