What is the treatment for polymorphic light eruption (polymorphic light reaction)?

Treatment of Polymorphic Light Eruption

The primary treatment approach for polymorphic light eruption consists of rigorous photoprotection with broad-spectrum, high-UVA sunscreens combined with topical antioxidants, with prophylactic phototherapy (PUVA or narrowband UVB) reserved for moderate-to-severe cases that significantly impair quality of life. 1, 2

First-Line Management: Photoprotection and Topical Therapy

Basic Photoprotection (All Patients)

• Apply broad-spectrum sunscreens with high UVA protection potential (SPF ≥15) daily, as this forms the foundation of PLE management 3, 2, 4
• Avoid sun exposure during peak hours (10 AM to 4 PM) and seek shade when outdoors 3
• Use protective clothing and textiles as physical barriers to UV radiation 2, 5

Topical Antioxidant Formulations (Moderate-to-Severe PLE)

• A formulation containing 0.25% alpha-glucosylrutin, 1% tocopheryl acetate (vitamin E), and broad-spectrum UVA-protective sunscreen (SPF 15) is highly effective for prophylaxis 4
• This combination is significantly more effective than sunscreen alone, preventing PLE in 96.6% of treated areas versus 58.7% with sunscreen only (P<0.001) 4
• Apply 30 minutes prior to sun exposure 4

Acute Symptom Management

• Potent topical corticosteroids should be applied to active lesions to manage provoked eruptions 1, 6
• Oral corticosteroids (prednisolone 40-50 mg) may be used for severe acute flares 1

Second-Line Management: Prophylactic Phototherapy

Indications for Phototherapy

Phototherapy is indicated for patients with moderate-to-severe PLE who experience substantial quality of life impairment despite optimal photoprotection 1, 2

PUVA Therapy Protocol

• PUVA is administered twice weekly (UK standard) in early spring, typically for 12-20 treatments 1
• Most centers use 8-methoxypsoralen (8-MOP), though 5-MOP and topical trimethylpsoralen are alternatives 1
• Timing is critical: administer in early spring to maintain photoprotection through mid-summer 1
• Starting too early risks loss of protection by peak summer; starting too late increases provocation risk 1

Narrowband UVB as Alternative

• Narrowband UVB is equally effective to PUVA, with 88-89% of patients reporting good or moderate improvement 1
• NB-UVB may be preferred due to lower long-term skin cancer risk compared to PUVA 1

Critical Precautions During Phototherapy

• Risk of provoking PLE is high (12-50% with PUVA, 48-62% with UVB), particularly during initial exposures 1
• Prophylactic measures to prevent provocation include:
  • Oral prednisolone (40-50 mg) for the first 2 weeks of phototherapy 1
  • Routine prophylactic application of potent topical corticosteroid after each exposure 1
  • Lower initial doses with gradual increments 1
• If provocation occurs, manage with potent topical steroids and reduce dose increments or omit 1-2 treatments 1
• Pruritus affects 18-33% of patients and may require oral corticosteroids 1

Post-Phototherapy Maintenance

• Continued natural sunlight exposure is essential post-treatment to maintain photoprotection through summer 1
• Recommendations range from 2 hours weekly to cautious daily exposure with sunscreen for extended outdoor activities 1
• Annual desensitization is generally not recommended due to cumulative skin carcinogenesis risk 1

Treatment Algorithm by Severity

Mild PLE

• Broad-spectrum sunscreen with high UVA protection 2, 4
• Behavioral sun avoidance measures 3, 2
• Topical corticosteroids for breakthrough lesions 6

Moderate-to-Severe PLE

• All measures for mild PLE plus:
• Topical antioxidant formulation (alpha-glucosylrutin + vitamin E + sunscreen) 2, 4
• Consider prophylactic phototherapy if quality of life significantly impaired 2, 6

Severe PLE

• Prophylactic phototherapy (PUVA or NB-UVB) with corticosteroid cover 1, 2
• Initiate in early spring with close monitoring 1

Therapy-Resistant PLE

• Consider systemic immunomodulation or immunosuppression on individual basis 2
• Antimalarials may be effective in select cases 5, 6

Important Clinical Pitfalls

Avoid these common errors:

• Do not start phototherapy too early (protection wanes by mid-summer) or too late (increases provocation risk) 1
• Do not use phototherapy without prophylactic corticosteroid cover in severe cases 1
• Do not recommend annual PUVA desensitization routinely due to cumulative carcinogenic risk 1
• Do not rely on sunscreen alone in moderate-to-severe cases—antioxidant formulations are significantly more effective 4
• Recognize that UVB-protective sunscreens fail in UVA-induced PLE, which represents the majority of cases 7

Long-Term Considerations

• Patients receiving >150-200 PUVA exposures require annual skin cancer surveillance 1
• The benefit of repeated phototherapy courses must be weighed against long-term skin carcinogenesis risk 1
• Most patients achieve adequate quality of life improvement with photoprotection and topical antioxidants without requiring phototherapy 2