Novel TFG – RET fusion in a spindle cell tumour with S100 and CD34 coexpresssion

The classification of spindle cell tumours with monomorphic morphology and lacking a clear immunophenotype remains challenging. Recurrent fusions involving receptor tyrosine or cytoplasmic kinase genes have been described in various spindle cell tumours1-4 . Among these, spindle cell tumours with monomorphic morphology displaying distinct stromal and perivascular hyalinization and co-expressing S100 and CD34 can be grouped into an entity featuring recurrent fusions involving RAF1, BRAF and NTRK1/2 genes2 . A case with similar morphology showing NCOA4-RET fusion was also described recently5 . In this report, we describe a case occurring in a child in which a novel gene fusion TFG-RET was identified. This article is protected by copyright. All rights reserved.