What are the indications and precautions for using ultraviolet (UV) therapy in patients with dermatological conditions, such as psoriasis or vitiligo, or in newborns with jaundice?

UV Therapy for Dermatological Conditions

For vitiligo, narrowband UVB (NB-UVB) phototherapy is the preferred UV treatment over PUVA, demonstrating superior efficacy with 36% of patients maintaining >75% repigmentation at 12 months compared to 24% with PUVA, and a lower relapse rate (12% vs 28%). 1, 2

Indications for UV Therapy

Vitiligo

• NB-UVB should be reserved for patients who have failed topical treatments (potent corticosteroids or calcineurin inhibitors) and have either widespread disease or localized vitiligo with significant quality of life impairment 1, 3
• Ideal candidates are patients with darker skin types (IV-VI) where depigmentation is most visible and distressing 1, 4
• Both children and adults can be treated, though children require more conservative approaches 1, 3

Psoriasis

• NB-UVB is recommended as first-line phototherapy for moderate to severe pediatric plaque and guttate psoriasis 1
• PUVA should only be considered for chronic plaque psoriasis that has not responded adequately to NB-UVB, or for especially thick/extensive disease 1
• Treatment frequency is typically 3 times per week on non-consecutive days 1, 2

Other Dermatoses

• Atopic dermatitis: NB-UVB preferred; PUVA only if NB-UVB fails 1, 5, 6
• Cutaneous T-cell lymphoma (mycosis fungoides): PUVA is first-line for plaque-stage disease 1
• Polymorphic light eruption: PUVA considered if UVB fails 1

Treatment Protocol for Vitiligo

Dosing Schedule

• Administer NB-UVB three times weekly on non-consecutive days 2
• Maximum cumulative limit: 200 treatments for skin types I-III 1, 2
• Higher limits may be considered for skin types IV-VI at clinician discretion, though specific upper limits lack evidence 1, 4

Monitoring Requirements

• Document baseline disease extent with photographs using standardized scoring systems (VASI or VETF) 2, 3
• Evaluate repigmentation every 2-3 months with serial photographs 1, 2, 3, 4
• This objective assessment allows timely treatment adjustments 3

Expected Outcomes and Response Patterns

Efficacy Data

• Approximately 36% maintain >75% repigmentation at 12-month follow-up with NB-UVB 1, 2
• Hands and feet respond poorly regardless of treatment adherence 1, 2
• Facial lesions typically respond better than non-facial areas 3
• NB-UVB does not alter the natural history of vitiligo—patients must understand this is a symptomatic treatment only 1

Relapse Rates

• 12% of NB-UVB patients experience relapse with worse vitiligo than baseline at 12 months 1, 2
• This compares favorably to 28% relapse rate with PUVA 1

Critical Precautions and Safety Considerations

Skin Cancer Risk

• UV phototherapy does not significantly increase risk of nonmelanoma skin cancer or melanoma in vitiligo patients (meta-analysis of 228,607 patients) 7
• This finding held true regardless of number of NB-UVB sessions or geographic location 7

Treatment Limits and Photodamage

• Vitiliginous skin has greater susceptibility to sunburn and photodamage due to melanin absence, necessitating more stringent safety limits than for psoriasis 1
• The 200-treatment limit for skin types I-III is arbitrary but based on psoriasis data extrapolated with added caution 1

Pediatric Considerations

• NB-UVB is safe and effective in children with extensive or refractory vitiligo 2, 3
• NB-UVB is strongly preferred over PUVA in children due to superior safety profile—no 24-hour protective eyewear requirement 1, 3, 5
• Psychological support for both child and parents is essential 2, 3
• Parents can assist with treatment compliance by ensuring proper eyewear use and minimizing movement during sessions 5

Common Pitfalls to Avoid

Patient Counseling Failures

• Patients must be informed before starting that:
  • Not all patients respond to treatment 1
  • Hands and feet respond poorly in all patients 1
  • Treatment does not change disease natural history 1
  • There are cumulative treatment limits due to potential side-effects 1

Inappropriate Treatment Selection

• Do not use PUVA as first-line therapy for vitiligo—NB-UVB demonstrates superior efficacy and better color matching of repigmented skin 1
• PUVA should only be considered for widespread vitiligo if NB-UVB has failed 1
• Avoid broadband UVB for vitiligo—it is not effective 1

Monitoring Deficiencies

• Failure to use standardized photographs prevents objective assessment of treatment response 2, 3
• Inadequate frequency of monitoring (should be every 2-3 months) may delay recognition of treatment failure 1, 2, 4

Alternative UV Modalities

Excimer Laser (308 nm)

• May be efficacious for localized vitiligo but has limited supporting evidence 1, 5
• Useful for targeted treatment of specific lesions 1
• Data on repigmentation amount, cosmetic acceptability, and permanence are lacking 1

PUVA Therapy

• Only consider PUVA for vitiligo after NB-UVB failure 1
• Oral PUVA requires strict 24-hour protective eyewear use 5
• Treatment limit: 150 treatments for skin types I-III 1
• Higher risk of worse disease at follow-up compared to NB-UVB 1