Comparison Study of Two Rituximab Regimens in the Remission of ANCA Associated Vasculitis

Inclusion Criteria: * Granulomatosis with Polyangiitis Or microscopic polyangiitis complying Or kidney-limited disease With or without detectable ANCA (anti-neutrophil cytoplasmic antibodies) at the time of diagnosis or relapse, and at remission. * Who have achieved remission using a treatment combining corticosteroids and an immunosuppressive agent, including corticosteroids, cyclophosphamide IV or oral (the use of another immunosuppressant is allowed, according to the current French guidelines, as well as plasma exchanges and/or IV immunoglobulins, or rituximab). * Interval of 1 month between the end of the immunosuppressant treatment and the randomization time if cyclophosphamide or methotrexate were used, interval between 4 and 6 months if rituximab was used * Age \> 18 years without age limit higher when the diagnosis is confirmed. * Informed and having signed the consent form to take part in the study. Exclusion Criteria: * Other systemic vasculitis * Secondary vasculitis (following neoplastic disease or an infection in particular) * Induction treatment with a regimen not corresponding to that recommended in France. * Patient who has not achieved remission. * Incapacity or refusal to understand or sign the informed consent form. * Incapacity or refusal to adhere to treatment or perform the follow-up examinations required by the study. Non-compliance * Allergy, documented hypersensitivity or contraindication to the study medication (cyclophosphamide, corticosteroids, …