The grouping of these two entities, which were separated until then, is grounded in an overlapping histological description, associated with a shared genetic signature: the fusion of the NGFI-A-binding protein 2 (NAB2) and signal transducer and activator of transcription 6 (STAT6) genes due to an inversion at chromosome 12q13, which is a hallmark for all SFT, regardless of their localization, since its first description in 2013 [2]. This evidence concerns the gene STAT6 and solitary fibrous tumor.