Immunosuppressive Therapy Alone Versus Plus Oral Anticoagulation in the Treatment of VT Associated With Behcet's Disease

Inclusion Criteria: * Participants must meet the following criteria to be eligible for the study: Age between 18-50 years old. Diagnosed with Behçet's Disease according to the International Study Group (ISG) criteria. No prior vascular involvement or no previous immunosuppressive therapy for vascular involvement. Confirmed venous thrombosis in the lower extremity within the last 14 days before randomization. Venous thrombosis diagnosis confirmed by: Non-compressible venous segment in ultrasound, OR A significant (\>4 mm) increase in thrombus diameter in an already abnormal segment, OR New intraluminal filling defect on venography, CT, or MR angiography. Female participants must: Not be pregnant or breastfeeding. Use effective contraception if of childbearing potential. Be postmenopausal (no menses for at least 1 year) or have undergone surgical sterilization. Ability to provide written informed consent and comply with study requirements. Exclusion Criteria: * Participants will be excluded if they meet any of the following criteria: Presence of any aneurysm. Chronic multisystemic disease other than Behçet's Disease. History of intolerance to Rivaroxaban. Use of immunosuppressive drugs (azathioprine, mycophenolate mofetil, cyclosporine, cyclophosphamide, TNF inhibitors, or interferon-gamma) within the last 6 months. Prolonged corticosteroid use (\>3 months) for Behçet's Disease mucocutaneous symptoms. Prior anticoagulant therapy: Low molecular weight heparin, fondaparinux, or unfractionated heparin for \>48 hours before randomization. More than one dose of vitamin K antagonists before randomization. Thrombectomy, vena cava filter placement, or fibrinolytic therapy for the current thrombotic episode. Planned administration of a live vaccine within 30 days after randomization. Clinically significant acute or uncontrolled chronic diseases (e.g., cardiovascular, pulmonary, hematologic, gastrointestinal, hepatic, renal, neurological, malignancy, or infectious diseases) that may interfere with study results. Planned surgical procedure or significant medical condition deemed unsuitable for the study by the investigator. History of malignancy within the last 5 years (except adequately treated basal or squamous cell carcinoma or carcinoma in situ of the cervix). Renal impairment (Creatinine clearance \<30 ml/min). Severe liver disease (e.g., acute hepatitis, active chronic hepatitis, cirrhosis, or ALT \>3 times the upper limit). Active bleeding or high bleeding risk contraindicating anticoagulant therapy. Uncontrolled hypertension (SBP \>180 mmHg or DBP \>110 mmHg). Severe anemia (Hemoglobin \<10 mg/dL). Women who are pregnant, breastfeeding, or of childbearing potential without contraception. Use of strong CYP3A4 inhibitors or inducers (e.g., protease inhibitors, systemic ketoconazole, rifampin, carbamazepine, phenytoin). Participation in another experimental drug study within the last 30 days. Life expectancy of less than 3 months. History of serious infections within the last 60 days (e.g., bacterial endocarditis, tuberculosis, opportunistic infections). Active substance or alcohol abuse or history of substance dependence within the last year. Positive screening for Hepatitis B surface antigen, Hepatitis C antibody, or known HIV-1 infection. Known coagulation disorders or laboratory abnormalities (e.g., DMID toxicity scale Grade 3 or higher). History of suicidal behavior in the last 6 months or suicidal ideation (C-SSRS type 4 or 5) in the last 2 months.