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Phototherapy

John Montgomery5 min read

Phototherapy

Phototherapy is controlled ultraviolet light treatment given in hospital dermatology departments. For eczema the standard modality is narrowband UVB (NB-UVB, 311–313 nm, TL-01 lamps). The patient stands in a whole-body cabinet two or three times a week. The starting dose is set by skin type and increased in small steps each session (Dayal 2017: start 50 mJ/cm², +10% per session). UV light dampens the Th2 inflammation of Atopic Dermatitis and corrects the imbalance between regulatory and effector T cells, which reduces itch and allows Topical Corticosteroids to be used less. Older options such as broadband UVB, UVA1 and PUVA (psoralen plus UVA) are now rarely used, and the AAD advises against PUVA (unverified).

Phototherapy [treats] Atopic Dermatitis Phototherapy [relates] Topical Corticosteroids

Evidence in children. The paediatric evidence is entirely observational, with no RCTs in young children. Dayal et al. (2017) treated 30 children aged 4–14 with moderate–severe AD twice weekly for 12 weeks. Ninety per cent cleared, mean SCORAD fell from 30.4 to 7.8, itch and sleep improved, and the benefit held over two years of follow-up. A Glasgow series of 77 children (median age 12, range 4–16) found that 68% of eczema patients cleared after a median of 24 treatments (Jury 2006). A Tel Aviv series of 129 children reported clearance in only 25% of AD patients (Pavlovsky 2011).

Conflict: [Dayal et al., 2017] says 90% of children with moderate–severe AD cleared on NB-UVB. [Pavlovsky et al., 2011] says only 25% of children with AD cleared (Jury et al., 2006: 68%). Differences in severity (Dayal: 90% moderate), clearance definition and skin type likely explain this. Unresolved — add to open_questions.

SCORAD [supports] Phototherapy

Guidelines. NICE CG57 (2007) puts phototherapy at the severe step for children. It should be considered only when “other management options have failed or are inappropriate” and there is a significant impact on quality of life, it must be supervised by dermatology staff experienced with children, and severity and quality of life must be documented first. The American Academy of Dermatology 2023/24 guideline (Davis et al., GRADE) gives a conditional recommendation for phototherapy, but it covers adults only. Strong recommendations in that guideline go to Dupilumab and the JAK inhibitors, and systemic corticosteroids are advised against. The British Association of Dermatologists patient leaflet says phototherapy is “not usually recommended for children” and that commercial sunbeds must never be used. For a toddler with severe eczema, specialists usually move to Wet Wrap Therapy, Systemic Immunosuppressants or dupilumab (licensed from 6 months) before phototherapy.

NICE CG57 [regulates] Phototherapy American Academy of Dermatology [supports] Phototherapy British Association of Dermatologists [opposes] Phototherapy

Practical limits for 1–4-year-olds. The youngest children in the published series were 4. A toddler has to stand still, alone, in a cabinet wearing UV-protective goggles, two or three times a week for about three months, and families have to travel to a hospital unit each time. Jury et al. recorded anxiety as a problem in some children. Treatment-related problems include burning/erythema, reactivation of Herpes Simplex Virus (with the risk of Eczema Herpeticum) and chickenpox, and polymorphic light eruption, each of which can require a pause in treatment. Phototherapy also interferes with Patch Testing: UV within 1–2 weeks (up to 6 weeks in conservative advice) blunts patch reactions (Tam & Yu 2022).

Phototherapy [causes] Herpes Simplex Virus Phototherapy [contradicts] Patch Testing

Skin-cancer risk. The main reason phototherapy is held back in children is the lifetime cumulative UV dose. Pavlovsky et al. reported “one doubtful case of melanoma in situ” among 129 children, advised annual skin checks for life, and noted that longer follow-up is needed to establish the true carcinogenic risk. Jury et al. concluded that “concerns remain regarding long-term side-effects”. No study has followed children treated with NB-UVB into adulthood, so the risk for a toddler starting decades of potential UV exposure is unknown. Home sun-lamps and sunbeds are therefore unsafe substitutes.

No sunbeds or home UV lamps for toddlers

Commercial sunbeds and unsupervised UV devices give uncontrolled doses, can burn, and add to lifetime skin-cancer risk (BAD). Medical phototherapy uses measured, logged doses under specialist supervision only.

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