STAT6 and solitary fibrous tumor: In contrast, SFT patients who develop NAB2 exon 6-STAT6 exon16/17 fusion are usually younger, the tumors are often located in the deep inner soft tissues, such as the abdomen, retroperitoneum, pelvis and other regions, with a higher recurrence rate, and microscopically, the cells are usually rounded to ovoid in shape with higher mitotic activity (20).