Cyclophosphamide Systemic Sclerosis Associated Interstitial Lung Disease

Inclusion Criteria: * Age ≥ 18 years old * Signed informed consent * Patient with systemic sclerosis fulfilling the ACR -American college of rheumatology - (Masi et al. 1980) and/or Leroy and Medsger (LeRoy and Medsger 2001) diagnostics criteria with worsening ILD (interstitial lung disease) identified on a high resolution chest CT scan and by worsening of forced vital capacity (FVC) and/or total lung capacity (TLC) ≥10% and/or worsening of DLCO ≥ 15% as compared to values obtained within the 3 to 18 months preceding inclusion (for DLCO, in the absence of pulmonary arterial hypertension upon echocardiography) * Smokers may be included (DLCO must be performed at least 72h after stopping tobacco intake). * Patients with pulmonary hypertension (mean pulmonary arterial pressure \<35 mmHg upon right heart catheterisation) secondary to hypoxia due to pulmonary fibrosis will also be included into the study. * Physical examination prior to inclusion into the study (results must be given to the patient). -: Contraception considered effective by the investigator (abstinence and / or oral contraception or mechanical) for women of childbearing age (negative pregnancy test at baseline) * Affiliation with a mode of social security (profit or being entitled) Exclusion Criteria: * Prednisone prescribed a dose greater than 15 mg/d during the last 3 months. * Scleroderma renal crisis or acute or critical limb ischemia within the last year preceding inclusion, * Left ventricular ejection fraction below 40% evaluated by echocardiography. * Out of proportion pulmonary hypertension (mean pulmonary artery pressure above 35 mmHg upon right heart catheterization). * CYC treatment during the last 12 months. * Allergy, hypersensitivity or documented adverse events or contra-indications to the drugs used in the study (cyclophosphamide, Uromitexan, corticosteroids, domperidone ...) * Patients with a past history of cancer within four years before inclusion and/or a history of chemotherapy for cancer within four years before inclusion (in remission or without disease activity for more than four years). Inclusion is authorized for patients with a basal cell carcinoma in the last 5 years. * Severe infection: sepsis, cellulitis, gangrene in the last three months * Past history of cystitis related to cyclophosphamide treatment * Association to another connective disease : systemic lupus erythematosus, syndrome of Gougerot-Sjögren with anti-SSA/SSB, mixed connective tissue disease * Patient breastfeeding * Failure to sign the informed consent or unable to consent * Patient participating in another clinical trial * Injection of Rituximab within 6 months preceding inclusion * Methotrexate or Cellcept treatment at inclusion