BTK and synovial sarcoma: A variety of BTK inhibitors has been developed for the treatment of inflammatory and autoimmune disorders, including RA, SS, MS, SLE, urticaria, pemphigus, ITP, RD, etc. Some diseases, such as RA, SS, MS, and urticaria, which are quite different from hematological malignancies, are usually non-life-threatening and long-term diseases that call for safe therapies without unexpected off-target toxicities.