Study to Evaluate Lenalidomide Plus Dexamethasone in Patients With Newly Diagnosed POEMS Syndrome

Inclusion Criteria: 1. Patients must understand and voluntarily sign an informed consent form. 2. Older than 18 years old at the time of signing consent. 3. Meet the diagnostic criteria of POEM syndrome. 4. Must be cytotoxic treatment naive. However, previous or existing corticosteroid (prednisone or dexamethasone) or intravenous immunoglobin (IVIG) therapy is allowed. 5. Women of childbearing potential must understand that the study medication could have a potential teratogenic risk. They should undergo complete contraception during the study period. 6. Male subjects must agree to use condoms throughout study drug therapy. Exclusion Criteria: 1. Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the informed consent form. 2. Pregnant or lactating females. 3. Any of the following laboratory abnormalities: Absolute neutrophil count(ANC) of\<1.0×10E9 cell/L. Platelet count\<50×10E9 cell/L. Renal failure requiring dialysis. Serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \>3 times of the normal upper limit. 4. Prior history of malignancies, but not including basal cell carcinoma of the skin, squamous cell carcinoma of the skin, carcinoma in situ of the cervix, carcinoma in situ of the breast, and T1a or T1b prostate cancer. 5. Known hypersensitivity or prior history of uncontrollable side effects to dexamethasone therapy. 6. Prior use of cytotoxic drugs. 7. Subjects who are unable or unwilling to undergo antithrombotic therapy.