Lenalidomide in the Treatment of Refractory Cutaneous Dermatomyositis

Inclusion Criteria: 1. Male or non-pregnant、non-nursing female. 2. Age 18 to 75 years at the time of signing informed consent. 3. Fulfilling 2017 ACR/EULAR IIMs classification criteria for DM or ADM. 4. Disease activity with skin damage (CDASI ≥12) despite treatment with corticosteroids, immunosuppressive agents or biologics for more than 3 months. 5. Written informed consent obtained before taking part in the study. Exclusion Criteria: 1. Pregnant women or breastfeeding mothers, Male and female patients with recent fertility requirements. 2. Skin and mucosal lesions should exclude erythema multiforme, syphilis, Sweet disease, Stevens-Johnson syndrome, acne vulgaris, herpes simplex infection, periodic granulocytopenia, and acquired immunodeficiency. 3. Severe Concomitant disease: including heart failure (≥level Ⅲ, NYHA), respiratory failure, myelosuppression (WBC\<3.0×109/L or N\<1.5×109/L, HGB≤85g/L, PLT\<100×109/L), peripheral neuropathy. 4. Acute severe infections such as sepsis and cellulitis, active hepatitis B or C virus infection, active tuberculosis, and history of a positive test for, or any clinical suspicion of, human immunodeficiency virus (HIV). 5. Patients with risk factors for myocardial infarction (including a history of thrombosis), hypercoagulability, or with history of venous thromboembolism, including deep vein thrombosis and pulmonary embolism. 6. Patients with allergies or contraindications to lenalidomide or thalidomide. 7. Uncontrolled or rapidly progressive myositis or interstitial lung disease at the discretion of the investigator which is likely to warrant escalation in therapy beyond permitted background medications. 8. Recurrent or chronic bacterial, viral, fungal, mycobacterial, or other infections including HIV. 9. History of recurrent herpes zoster, disseminated (multi-dermatomal) herpes zoster, disseminated herpes simplex or ophthalmic zoster. Herpes zoster lesions within 90 days prior to screening. 10. Primary or secondary immunodeficiency. 11. Current uncontrolled renal, gastrointestinal, endocrine, pulmonary, cardiac, or neurologic disease, which, in the opinion of the investigator, might place the patient at unacceptable risk for participation in this study. 12. History of alcohol, drug, or chemical abuse within one year prior to signing the informed consent form. 13. Major surgery within 8 weeks prior to Screening or planned major surgery at any time during participation in the study. 14. Immunization with a live/attenuated vaccine within 4 weeks prior to Screening. 15. History of malignant tumor within 5 years prior to screening (stable disease for more than 6 months after completion of tumor treatment program can be enrolled).