What are the management and treatment strategies for patients with photodermatoses?

Management and Treatment of Photodermatoses

Foundation: Universal Photoprotection

All patients with photodermatoses require rigorous photoprotection as the cornerstone of management, regardless of specific diagnosis. 1

• Apply broad-spectrum sunscreens with SPF ≥30 (some guidelines specify ≥15) daily, emphasizing high UVA protection 1, 2
• Avoid sun exposure during peak UV hours (10 AM to 4 PM) 1, 3
• Wear protective clothing, wide-brimmed hats, and sunglasses 4
• Seek shade when outdoors 5

Acute Management of Active Lesions

For symptomatic eruptions, potent topical corticosteroids should be applied immediately to control inflammation. 1

• Use topical betamethasone or hydrocortisone butyrate for trunk lesions 1
• Apply 1% hydrocortisone for facial lesions 1
• For severe acute flares, oral prednisolone 40-50 mg may be administered 2, 5
• Manage pruritus with oral corticosteroids if topical therapy insufficient 2

Prophylactic Phototherapy: When and How

Indications for Phototherapy

Prophylactic phototherapy should be offered to patients with moderate-to-severe photodermatoses who experience substantial quality of life impairment despite optimal photoprotection. 1, 5

Choice of Phototherapy Modality

Narrowband UVB is the preferred first-line phototherapy for most photodermatoses, particularly in young patients and those requiring long-term treatment, due to lower skin cancer risk compared to PUVA. 2, 5

• Narrowband UVB demonstrates equivalent efficacy to PUVA (88-89% reporting good or moderate improvement) 2, 5
• PUVA remains an option when narrowband UVB is unavailable or ineffective 2

Specific Protocols by Condition

Polymorphic Light Eruption (PLE)

Administer narrowband UVB or PUVA twice weekly in early spring for 12-20 treatments to achieve photoprotection through mid-summer. 2, 5

• Start narrowband UVB at 70% of minimal erythema dose with 20% increments 5
• PUVA typically uses 8-MOP, though 5-MOP and bath PUVA are alternatives 2
• Timing is critical: too early and protection wanes by mid-summer; too late and eruptions may already have occurred 2

Critical precaution: The risk of provoking PLE during phototherapy is high (12-50% with PUVA, 48-62% with narrowband UVB), particularly during initial exposures. 2, 5

Prevention strategies for provocation:

• Administer oral prednisolone 40-50 mg for the first 2 weeks of phototherapy 2, 5
• Apply potent topical corticosteroid prophylactically after each exposure 2, 5
• Use small dose increments, especially initially 5
• If provocation occurs, manage with potent topical steroids, lower dose increments, and omit 1-2 treatments if severe 2

Chronic Actinic Dermatitis

PUVA phototherapy must only be undertaken in specialist units experienced in managing this disease, with close supervision under cover of topical or systemic corticosteroids. 2, 1

• Maintenance treatment may be required 2
• Annual repeated courses can be considered, but benefits must be weighed against long-term skin carcinogenicity risk 2

Solar Urticaria

Determine the action spectrum via monochromator phototesting in a specialized unit before initiating phototherapy, as treatment can potentially cause provocation, syncope, and anaphylaxis. 2

• Measure the minimal urticarial dose (MUD) before starting 2
• Initiate phototherapy at a dose lower than the MUD 2
• In patients with very low MUD, consider UVA alone or pre-PUVA UVA 2
• High-dose H1 antihistamines are first-line pharmacotherapy 1

Erythropoietic Protoporphyria

Narrowband UVB has shown effectiveness in 6 of 8 cases of cutaneous porphyria, particularly erythropoietic protoporphyria. 2

• No comparative trials exist for PUVA in EPP treatment 2

Post-Phototherapy Maintenance

Continued natural sunlight exposure is essential post-treatment to maintain photoprotection through summer. 2, 5

• Recommendations range from 2 hours weekly to cautious exposure with sunscreens for extended outdoor stays 2
• Annual desensitization is generally not recommended due to cumulative skin carcinogenesis risk. 2, 5

Long-Term Monitoring and Skin Cancer Surveillance

Patients receiving >150-200 PUVA exposures require annual skin cancer surveillance, and the benefit of repeated phototherapy courses must be weighed against long-term skin carcinogenesis risk. 1, 5

• Annual dermatologic examination of all sun-exposed areas is recommended 1
• Patients should immediately report any suspicious lesions 1
• The long-term risk of skin carcinogenesis with PUVA needs careful consideration against therapeutic benefit 2

Common Pitfalls to Avoid

• Do not administer phototherapy too early in the year (protection may wane by mid-summer) or too late (patient may have already suffered eruptions) 2
• Do not use PUVA for chronic actinic dermatitis outside specialist centers without appropriate corticosteroid cover 1
• Do not proceed with phototherapy for solar urticaria without first determining the action spectrum via specialized phototesting 2
• Do not recommend annual desensitization courses routinely due to cumulative carcinogenic risk 2, 5