Vitiligo affects approximately 1 to 2% of the global population and significantly impacts people's quality of life. Achieving the best treatment outcomes for vitiligo involves addressing the autoimmune inflammatory response for stopping the depigmentation process and promoting the differentiation of melanocyte stem cells to induce re-pigmentation. The loss of melanocytes in vitiligo is a result of an autoimmune process. The pathogenesis includes genetic and environmental factors together with metabolic, and oxidative stress that trigger innate then adaptive immunity against melanocytes. No individual mechanism can sufficiently account for all parts of this complex disease; instead, the convergence theory which combines immunological, biochemical, and environmental factors in genetically predisposed participants has been proposed as a unifying approach to understanding the pathophysiology of vitiligo. None of these proposed theories are in themselves sufficient to explain the different vitiligo phenotypes; and the overall contribution of each of these processes is still under debate, although there is now consensus on the autoimmune nature of vitiligo: melanocytes from participants with vitiligo are more susceptible to oxidative stress which triggers the release of inflammatory cytokines that will lead to activation of the innate immune response and subsequently to adaptive immune response through activation of autoreactive cytotoxic CD8+ T cells against melanocytes via abnormal JAK/STAT pathway activation. Despite the efficacy of JAK inhibitors in blunting the anti-melanocyte immune response, skin repigmentation still takes more than 1-2 years, and the repigmentation remains very difficult to achieve in some body locations. To overcome this lack of efficacy in some locations and the need of long duration of treatment, additional therapeutic options are needed.

Considering that the immune process primarily contributes to depigmentation while ultraviolet (UV) radiation stimulates the differentiation and proliferation of melanocyte stem cells for re-pigmentation, a combination therapy using HBO and narrowband UVB (NbUVB) could offer an optimal approach for treating vitiligo patients. The primary objectif is to assess the therapeutic efficacy of combining hyperbaric oxygen (HBO) therapy with phototherapy for the treatment of diffuse vitiligo, as measured by the change in Vitiligo Area Scoring Index (VASI) after 24 weeks of intervention.

• 1- Recruitment of patients corresponding to the inclusion and exclusion criteria from the active file of vitiligo patients followed in the dermatology department of Nice University Hospital (Hopital Archet).
• 2- Consultation with a hyperbaric physician to verify the absence of contraindications to HBO therapy, and performance of a urine pregnancy test.
• 3- UVB 2 sessions per week over 24 weeks + HBO therapy 40 sessions over 8 weeks (1/d; 5/7)
• T0- Completion of VASI and VSAS clinical scores by a dermatologist.
• T1- VASI and VSAS scores after 12 weeks of treatment by a dermatologist.
• T2- VASI, VSAS and VNS scores after 24 weeks of treatment by a dermatologist.

Inclusion Criteria:

• 1. Men and women diagnosed with non-segmental vitiligo for at least for 3 months 2. ≥ 18 years old 3. Body surface area (BSA) involvement between 4%-60% inclusive, excluding involvements at palms of the hands, soles of the feet, or dorsal aspect of the feet, and 4. BSA ≥0.5% involvement on the face 5. VASI ≥3 6. Active and stable vitiligo 7. 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 8. Affiliation to a social security system 9. Signed informed consent 10. Patient willing and able to attend all study visits.

Exclusion Criteria:

• 1. Immunocompromised patients 2. Personal history of skin cancer or photo dermatosis 3. Use of UVB photosensitizing drugs 4. Concomitant dermatosis which, in the opinion of the investigator, may interfere with the evaluation of vitiligo 5. Segmental or mixed vitiligo 6. Patients with more than 33% of leucotrichia on the lesions 7. Patients with contraindications to HBO therapy 8. Any other pathological condition or therapeutic treatment identified during the initial consultation and considered a contraindication to hyperbaric exposure 9. Patients with active infection or other systemic/ inflammatory disease 10. Tuberculosis or latent tuberculosis 11. Vulnerable people: pregnant or breast-feeding women, minors, adult under guardianship, deprived of freedom or with psychiatric condition 12. Participants in other clinical therapeutic studies involving a drug that could interfere with the present evaluation.