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New guidelines from American Academy of Dermatology for treatment of psoriasis with ultraviolet light therapy

November 19, 2017

In an effort to minimize the total dosage of PUVA, dermatologists often combine PUVA treatments with other therapies (such as retinoids) or in rotation with other treatments. In addition to the increased risk of skin cancer and skin aging with long-term use, other common side effects of PUVA include redness, itching, dryness, irregular pigmentation, nausea and vomiting. PUVA also is not recommended for use in children or in patients with certain medical conditions, which is why dermatologists closely evaluate patients before PUVA is considered as a treatment option for psoriasis.

Targeted Phototherapy (Excimer Laser)

With the introduction of the 308 nm monochromatic xenon-chloride laser for psoriasis in 1997, the use of phototherapy to treat localized lesions became more practical and more widely available. Excimer lasers selectively target affected lesions without treating unaffected skin - therefore minimizing the potential risk of exposing uninvolved skin to UV radiation. Another advantage is that since only the affected areas are treated, higher doses can be administered in fewer treatment sessions.

Although numerous studies have demonstrated that treatment with the excimer laser can clear psoriasis, there is limited information on the duration of remission and the recommended dosage and scheduling of therapy. Dr. Pariser explained that most patients experience long-term improvement following treatment with the excimer laser, and currently the dose of energy delivered is guided by the patients' skin type and thickness of the psoriasis plaques.

"Typically, patients receive treatment with the excimer laser two to three times a week, with a minimum of 48 hours between treatments," said Dr. Pariser. "Side effects are minimal and are limited to the treatment area, with redness, burning and darkening of the skin being the most common. There have been cases where blistering has occurred with the use of higher doses of energy, but for the most part treatments are well-tolerated - even in children."

Patient Considerations for UV Light Therapy

Like all treatments for psoriasis, some patients make better candidates for UV light therapy than others. Dr. Pariser added that before UV light therapy is considered, all patients must have a complete history and physical examination and be made aware of the potential long-term risks of this treatment.

"Patients with a known history of lupus (a chronic inflammatory disease) or xeroderma pigmentosum (a genetic disease characterized by extraordinary sensitivity to sunlight) should not be treated with phototherapy," said Dr. Pariser. "In addition, patients with atypical nevi, multiple non-melanoma skin cancers, multiple risk factors for melanoma, a history of melanoma, a history of photosensitivity disorder, or who are taking photosensitizing medications or are immunosuppressed as a result of organ transplantation should be screened carefully before starting UV light therapy."

Recommended dosing guidelines for both BB-UVB and NB-UVB vary by skin type, with light-skinned patients receiving much smaller initial and incremental doses of UV light than darker-skinned patients.

"For the right patients and with close monitoring by a dermatologist, UV light therapy can be a safe and effective treatment for psoriasis patients who might not have responded well to other traditional therapies or for various reasons might not be good candidates for systemic medications," said Dr. Pariser. "Dermatologists can recommend the best treatment plan for patients with mild to severe psoriasis, helping them improve their condition and overall quality of life."

SOURCE American Academy of Dermatology