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Polymorphic light eruption
Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports
Polymorphic light eruption (PLE) is a highly prevalent photosensitivity disorder, estimated to affect 11–21% people in temperate countries. Typically, PLE appears as a recurrent pruritic eruption comprising papules, vesicles and/or plaques, which occurs on photoexposed skin sites following sun exposure, and which heals without scarring. Other forms include purpura, erythema multiforme, pinpoint papular (in African Americans), and ‘juvenile spring eruption’ described in young boys. Commoner in females, the etiology is uncertain, although there is evidence of an immune basis. Most patients only experience symptoms on sunny vacations, while the most severely affected may also be symptomatic in winter months. The diagnosis of PLE is usually made clinically; history and patient examination or photographs are necessary to exclude other photodermatoses. In atypical cases, positive photoprovocation test to UVA and UVB-emitting lamps, and histology of photoprovoked eruption, confirm the diagnosis.
Management Strategy
For most patients with PLE, the rash is mild, self-limiting, and quickly settles within a few days of sun avoidance. Treatments may be prophylactic or suppressive, and depend on disease severity, availability of equipment, and patient choice. In the majority of patients, prophylactic management is by sun avoidance/reduced midday sun exposure, protective clothing, UV-protective umbrellas and swimsuits, and broad-spectrum sunscreens (i.e., UVA and UVB protective) . Gradual self-hardening by regular exposure to natural sunlight in early spring may also be helpful. For the more severe patient, the disease may be triggered within 15–30 minutes of sun exposure and may require additional therapy.
For any exacerbations, the use of a potent/very potent topical corticosteroid , used liberally to the affected skin for a few days, is usually sufficient to bring the condition under control. There is also some evidence that pretreatment with topical corticosteroid before natural sun exposure that is expected to induce a flare can be a helpful preventative measure. Oral antihistamines are helpful to alleviate pruritus but do not induce resolution and are not mainstays of treatment.
The mainstay of prophylactic management is phototherapy – narrowband UVB (312 nm), systemic photochemotherapy with PUVA (psoralen-UVA), or broadband UVB . This induces artificial skin hardening and can be administered in early spring, or just prior to a special sunny vacation abroad. Phototherapy administered for PLE is generally given as a relatively short course, over 4–6 weeks, using low initial UV doses compared with schedules used for psoriasis; the aim is to induce natural skin hardening rather than treat the disease. NB-UVB is the phototherapy of first choice due to its safety profile and convenience over systemic PUVA. NB-UVB has also superseded BB-UVB. There is a high risk of rash provocation (estimated up to 50%), which can be reduced by the use of potent/very potent topical corticosteroids immediately after each exposure. Any provocation of PLE can be managed by adjusting UV doses and use of corticosteroids. Specific advice should be given for continued regular cautious exposure to natural sunlight after completion of the course to maintain the level of hardening.
In PLE cases resistant to photoprotective measures and phototherapy, other antiinflammatory agents and immunomodulators include azathioprine, ciclosporin, hydroxychloroquine, beta-carotene, nicotinamide, omega-3 polyunsaturated fatty acids, topical flavonoids, polypodium leucotomos, and others.
Specific Investigations (Optional)
Antinuclear antibodies in patients with polymorphic light eruption: a long-term follow-up study
Tzaneva S, Volc-Platzer B, Kittler H, et al. Br J Dermatol 2008; 158(5): 1050–4.
Of the 472 patients with PLE who received PUVA, 12% had antinuclear antibodies (i.e., ANA titre>1:80), and 0.6% had anti-Ro/SS-A antibodies. Of all ANA-positive patients, 71% were followed up for a mean of 8 years; two-thirds had a persistently elevated ANA with median titre of 1:160, whereas in one-third the ANA titre had normalized. None progressed to lupus erythematosus (LE).
Routine ANA testing is unnecessary unless clinically indicated.
Textiles and sun protection
Robson J, Diffey BL. Photodermatol Photoimmunol Photomed 1990; 7(1): 32–4.
The tightness of the weave of clothing fabrics determines the amount of photoprotection; thus, while a typical crêpe blouse gives a sun protection factor (SPF) of only 5, a jersey T-shirt has an SPF of 32 and a silk blouse 280. From a practical viewpoint, holding the fabric up against bright lighting will give the patient some indication of the tightness of the weave and hence its suitability for protection. The transmission of UV radiation for all fabrics is increased when a fabric is wet.
Sunscreen application technique in photosensitive patients: a quantitative assessment of the effect of education
Azurdia RM, Pagliaro JA, Rhodes LE. Photodermatol Photoimmunol Photomed 2000; 16(2): 53–6.
The efficacy of the newer generation broad-spectrum sunscreens is well established. However, previous studies have demonstrated that photosensitive patients only apply approximately a quarter of the thickness of cream used under manufacturer’s test conditions, i.e., 2 mg/cm 2 . In this study, patient education resulted in sustained improvement in patient sunscreen application technique, with median sunscreen thickness on the face improving from a baseline of 0.33 mg/cm 2 to 1.51 mg/cm 2 at 6 months.
Is topical steroid effective in polymorphic light eruption?
Man I, Dawe RS, Ibbotson SH, et al. Br J Dermatol 2000; 142 (Suppl 57): 112–4.
Potent/very potent topical corticosteroids may be adequate for exacerbations of PLE. This small double-blind study shows that routine application of topical steroid immediately after UVB phototherapy prevented provocation in 5/7 patients .
Topical steroids applied immediately after phototherapy may reduce the incidence and severity of provoked rash during treatment and enable patients to complete the course.
A comparison of narrow band phototherapy (TL-01) and photochemotherapy (PUVA) in the management of polymorphic light eruption
Bilsland D, George SA, Gibbs NK, et al. Br J Dermatol 1993; 129: 708–12.
A group of 13 patients were randomized to receive NB-UVB (and placebo tablets) and another of 12 to receive PUVA three times a week for 5 weeks in spring. About 85% of patients in each treatment group were adequately protected from developing PLE during summer, and there was no significant difference in the efficacy of NB-UVB and PUVA.
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