Are You Confident of the Diagnosis?

What you should be alert for in the history

Be alert for a delayed reaction after sun exposure on exposed skin in someone who recently went on a trip or vacation to a sunny area; ie, an area with more sun than their normal environment. Polymorphous light eruption (PMLE) typically occurs in the Spring season but may occur in any season when the individual is away from home on vacation in a sunny area. The rash persists for approximately 7-10 days and is typically very pruritic. It affects certain areas of the body, but typically not the whole body or all exposed areas.

Characteristic findings on physical examination


In women, the chest, arms, and thighs are most commonly affected. In men, the arm and thighs are most commonly affected (Figure 1). The face is almost never involved.

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Figure 1.

Erythematous juicy papules scattered on the arm.


The morphology is marked by eruption of erythematous juicy papules (Figure 2). The eruption typically does not have frank vesicles, though vesicles can occur.

Figure 2.

Characteristic erythematous polymorphic juicy papules with minimal or no scale.

Diagnosis confirmation

The diagnosis is based on clinical history and is a diagnosis of exclusion, after ruling out lupus, chronic actinic dermatitis, photo-allergic contact dermatitis, and photo-drug reaction. Histopathology may support the diagnosis, but usually is not necessary. The differential diagnosis includes lupus, chronic actinic dermatitis, photo-allergic contact dermatitis, photo-drug reaction, and airborne contact dermatitis.

Who is at Risk for Developing this Disease?

Anyone may be at risk for this disease. It primarily affects young adults, particularly young women. Those affected are primarily people living in Northern climates with less sun exposure who travel to Southern climates with greater sun exposure. People who live closer to the equator are less likely affected.

What is the Cause of the Disease?

The etiology is unknown. It is thought to be a delayed hypersensitivity reaction to an antigen produced by sun exposure, in particular uiltraviolet (UV) A or UVA/UVB spectrum.


There is some evidence that individuals who develop this reaction do not have the normal photo-immune suppression that occurs in irradiated skin.

Systemic Implications and Complications

Typically, there are no associated systemic complications.

Treatment Options


-Avoidance of sun exposure, including protective clothing and broad spectrum sunscreen, especially those that contain Ecamsule (Mexoryl) and butyl-methoxydibenzoylmethane (Avobenzone).

-Prevention by prophylactic treatment with PUVA and NBUVB phototherapy and/or anti-malarials.

-Phototherapy options include psoralens and ultraviolet A (PUVA) and narrow-band ultraviolet B (NBUVB). Light therapy should be administered at the same doses as for psoriasis, starting 3-4 weeks before travel to sunny climate.

Anti-malarials, including hydroxychloroquine 200-400 mg per oral daily, should be administered starting 1 week before and continued throughout the duration of travel to sunny climate


– Cool soaks and/or compresses as needed.

– Emollients as needed, including Vaseline or Aquaphor ointments, calamine lotion.

– Mid to high-potency topical corticosteroids twice a day as needed;, eg.,Triamcinolone 0.1% ointment, Fluocinonide 0.05% ointment (Lidex), Clobetasol Propionate 0.05% ointment (Clobex, Temovate)

– Antihistamines as needed for itch;, eg, Diphenhydramine (Benadryl) and Hydroxyzine (Atarax)

– Systemic steroids at 1mg/kg/day if necessary with 2-week taper

Optimal Therapeutic Approach for this Disease


– Prevention by avoidance of sun exposure.

– Ecamsule (Mexoryl) and butyl-methoxydibenzoylmethane (Avobenzone) in combination are better at sun-protection from polymorphous light eruption than either agent alone.

– Prevention by prophylactic treatment with PUVA and NBUVB phototherapy and/or antimalarials.


– Symptomatic relief with emollients, topical steroids, and antihistamines.

– Systemic steroids may be necessary for severe cases.

Patient Management

The patient can be followed can be followed for prophylactic treatment with phototherapy and/or antimalarials until lesions clear. Education should be provided for avoidance of future avoidance of sun exposure, and prophylactic treatments for prevention of PMLE.

Unusual Clinical Scenarios to Consider in Patient Management


What is the Evidence?

Deng, D, Hang, Y, Chen, H, Li, H. “Prevalence of photodermatosis in four regions at different altitudes in Yunnan province, China”. J Dermatol. vol. 33. Aug 2006. pp. 537-40. (Population-based study of the prevalence of polymorphous light eruption and chronic actinic dermatitis and analysis of demographics, higher or lower elevations and duration of sun exposure.)

Aubin, F. “Why is polymorphous light eruption so common in young women”. Arch Dermatol Res. vol. 296. Oct 2004. pp. 240-1. (Letter to a journal editor discussing the effect of 17-beta-estradiol on UVB induced immunosuppression and a potential role in the pathogenesis of polymorphous light eruption, particularly in young women.)

Murphy, GM, Logan, RA, Lovell, CR, Morris, RW, Hawk, JL, Magnus, IA. “Prophylactic PUVA and UVB therapy in polymorphic light eruption–a controlled trial”. Br J Dermatol. vol. 116. Apr 1987. pp. 531-8. (Double-blind controlled trial of low-dose oral psoralen UVA and UVB prophylaxis in 42 patients with polymorphic light eruption.)

Bilsland, D, George, SA, Gibbs, NK, Aitchison, T, Johnson, BE, Ferguson, J. “A comparison of narrow band phototherapy (TL-01) and photochemotherapy (PUVA) in the management of polymorphic light eruption”. Br J Dermatol. vol. 129. Dec 1993. pp. 708-12. (Randomized trial demonstrating equal efficacy of narrowband UVB and psoralen UVA in 25 patients over a 4-month period.)

Boonstra, HE, van Weelden, H, Toonstra, J, van Vloten, WA. “Polymorphous light eruption: A clinical, photobiologic, and follow-up study of 110 patients”. J Am Acad Dermatol. vol. 42. Feb 2000. pp. 199-207. (Retrospective study of 110 patients with polymorphous light eruption and analysis of photoprovocation and photopatch test results.)