Phototherapy
Several studies have documented the safe and effective use of UVA and UVB phototherapy [8] in children and adolescents with severe disease who do not respond to topical corticosteroids. Thye can be treated with narrow-band ultraviolet B therapy.
Usually, 10 to 30 treatments are needed, given two to three times a week, for a response to be observed. After all, injuries are eliminated, the frequency can be reduced to once a week for a month, and then every two weeks for two months, as needed and tolerated.
When narrowband ultraviolet B therapy is not available, natural sunlight can be an alternative. Patients should be instructed to start with 10 minutes of direct, unprotected sunlight between 10 am and 2 pm, progressively increasing the duration of exposure to a maximum of 30 minutes daily.
Patients with very light skin and those with red or blond hair should limit the exposure time to a maximum of 20 minutes. Unaffected areas of the skin should be covered to limit unnecessary sun exposure.