NAB2 and solitary fibrous tumor: In the 2020 WHO Classification of Soft Tissue and Bone Tumors [5], SFT is categorized as an intermediate fibroblastic neoplasm with low metastatic potential, defined by the NGFI-A binding protein 2 (NAB2)-signal transducer and activator of transcription 6 (STAT6) gene fusion [6,7].