 Dermatomyositis DM is a rare, progressively debilitating disorder that affects the muscle causing weakness and skin causing a rash in most affected patients. DM can also involve multiple body systems including the lungs, joints, gut and heart. Therapy for DM involves administering corticosteroids, typically with an immunosuppressive agent, but treatment options for refractory DM are very limited. This research is being done to determine the safety and effectiveness of a Janus kinase JAK inhibitor called Tofacitinib in adults with active, treatment-refractory dermatomyositis. The investigators will also look for specific biomolecular changes in blood, skin, and muscle when it is exposed to Tofacitinib. Tofacitinib is approved by the Food and Drug Administration FDA for the treatment of rheumatoid arthritis. The study aim is to conduct a 12-week, open-label, pilot study with up to 10 patients who have refractory DM to assess whether a JAK inhibitor effectively and safely reduces the symptoms of DM in both the skin and muscle. This study consists of up to 9 study visits over 6 months. There is an optional treatment extension period of 4 weeks. All subjects will undergo follow-up assessments 4 weeks after stopping treatment. Results from this study will contribute to the design of future trials that will further define the role of JAK inhibitors in the treatment of patients with dermatomyositis. 