Inclusion Criteria:  1. Patients with non-segmental vitiligo. 3 groups of patients will be selected: Patients with a long-lasting disease (more than 2 years) and no new or growing lesion since at least 2 years Patients with a long-lasting disease (more than 2 years) and with at least one new lesion since less than 6 months  Patients developing for the first-time vitiligo lesions with all the lesions no older than 6 months 2. ≥ 18 and <35 years to have a homogeneous distribution of age between the three groups, as 80% of vitiligo cases start before the age of 30.  3. Patient with at least one lesion of more than 2 cm² not located on the face, hands or feet.  4. Patient needing a treatment with oral minipulses of steroids and phototherapy 5. For women of child-bearing age, an effective contraception (estroprogestative pill, contraceptive implant, IUD, condoms or tubal ligation) should be used for more than one month before the inclusion in the study. A urine pregnancy test (βHCG in urines) will be performed.  6. Affiliation to a social security system 7. Signed informed consent  Exclusion Criteria:  1. Pregnant or breast-feeding women. Or women who plan to get pregnant during the study duration.  2. Segmental or mixed vitiligo 3. Vitiligo located only on face, hands and feet 4. Exposure to solar or artificial UV during the months before inclusion 5. Concomitant use of topical or systemic immunosuppressive medication or steroids 6. Patients suffering from photodermatosis or taking photosensitive drugs 7. Personal history of skin cancer. 8. Patients with diabetes, high blood pressure, osteoporosis or any other contra-indication to the use of systemic steroids.  9. Vulnerable people: pregnant or breast-feeding women, minors, adult under guardianship or deprived of freedom 10. Participants in other clinical therapeutic studies involving a drug that could interfere with the present evaluation