Medical Care
Photoavoidance (eg, avoiding sunlight, wearing protective clothing, using sunscreen) remains a key factor in the care of patients with polymorphous light eruption (PMLE). Broad-spectrum sunscreens are recommended because sunscreens with high sun protection factor (SPF) values are not necessarily protective against UVA-induced PMLE.
DeLeo et al reported that sunscreen with 4 UVA filters (ie, ecamsule 3%, octocrylene 10%, avobenzone 2%, and titanium dioxide 5%) was more effective for preventing PMLE flares than a sunscreen with only a triad of UVA blockers. [47] Other studies support the use of UVA blockers to help prevent PMLE, [48] including a report that describes a lower percentage of PMLE (0% at 2 mg/m2; 33% at 1 mg/m2) in subjects who used high UVA sunscreen protection versus those who used lower UVA sunscreen protection (73% at 2 mg/m2; 80% at 1 mg/m2). [49]
Owing to the tendency of patients to experience hardening, phototherapy with UVA1, narrowband UVB, psoralen plus UVA (PUVA), or broadband UVB can harden the skin against the development of PMLE. A case of PMLE that failed UVA1 therapy has been reported [41] ; a woman aged 37 years developed a recalcitrant PMLE that lasted 5 weeks after completion of UVA1 phototherapy. Treatment given at the beginning of spring for several weeks may prevent flare-ups throughout the summer. PUVA was found to be superior to UVB in several studies, controlling the outbreaks in 90% of patients. [50] In another study of 25 patients with severe PMLE, narrowband UVB (311 nm) was found to be an equally effective alternative to PUVA. [51] Oral prednisone may be useful in conjunction with phototherapy to avoid eruption during therapy. Barolet and Boucher report on the use of light-emitting diode nonthermal therapy as a prophylactic measure for PMLE. [51]
Antioxidants have also been suggested to help prevent PMLE lesions. In a randomized, double-blinded, placebo-controlled clinical study by Hadshiew et al, [52] the efficacy of a new topical formulation was compared with a broad-spectrum sunscreen. The new product contained 0.25% alpha-glucosyl-rutin (a natural, modified flavonoid) and 1% tocopheryl acetate (vitamin E). Thirty patients with a history of PMLE were pretreated with the cream 30 minutes prior to daily photoprovocation with UVA irradiation of 60-100 J/cm2 to the upper arms. The authors found a statistically significant difference (P< .001) between the antioxidant-containing formulations and placebo and between the sunscreen-only formulation. Only a single patient treated with the new antioxidant UV-protective gel formulation developed clinical signs of PMLE in the area treated. In comparison, 62.1% of the placebo-treated areas and 41.3% of the sunscreen-only treated areas showed mild-to-moderate signs of PMLE. The authors suggested that combining a potent antioxidant with a broad-spectrum sunscreen is far more effective in preventing PMLE than sunscreen alone. Also see Sunscreens and Photoprotection.
The use of topical antioxidants like 0.25% alpha-glucosyl-rutin and 1% vitamin E along with a broad-spectrum highly UVA–protective sunscreen was found to be helpful in PMLE patients. [53]
Some authorities believe that vitamin therapy is helpful in the treatment of PMLE. Nicotinamide was successful in 60% of 42 patients treated with 3 g/d orally for 2 weeks. [54] The rationale for its use was the knowledge that it blocks the formation of kynurenic acid, a photosensitizer that may play a role in PMLE. Ahmed et al found that oral vitamin E supplementation (400 IU) and use of sunblock decreased the markers of oxidative stress and lipid peroxidation in patients with PMLE. [53]
Systemic vitamin C and vitamin E do not prevent photoprovocation test reactions in persons with PMLE. [55]
The effect of topical calcipotriol (an analog of calcitriol, 1,25-dihydroxyvitamin D3) was described by Gruber-Wackernagle et al. [56] They evaluated the preventive effect of topical calcipotriol in a randomized, double-blinded, placebo-controlled, intraindividual half-body trial. Thirteen patients with PMLE applied cream (calcipotriol or placebo) topically to symmetrically located pairs of test areas twice daily for 7 days before photoprovocation with solar-simulated UV radiation was begun. The authors used a specific PMLE test score based on affected area, skin infiltration, and pruritus to rate symptom severity at 48, 72, and 144 hours after the first photoprovocation exposure. They found pretreatment with calcipotriol, compared with placebo, significantly reduced PMLE symptoms on average by 32% (P = .0022), suggesting a possible benefit from prophylactic use of topical 1,25-dihydroxyvitamin D3 analogs in patients with PMLE.
Topical corticosteroids are useful, as would be expected in many dermatoses associated with lymphocytic skin infiltrate. They are temporary measures for symptomatic relief. Adverse effects such as potential tachyphylaxis and skin atrophy limit their long-term use.
Systemic steroids may be needed to suppress acute flares or extensive generalized eruption. Adverse effects of prolonged systemic steroid use include decreased glucose tolerance, osteoporosis, impaired immunity, and weight gain. Obviously, this treatment can only be offered intermittently and for a short period. It may also be considered for patients prophylactically going on vacation or for those patients experiencing other unavoidable sun exposure.
Antihistamines may help with pruritus.
Antimalarials at low doses are sometimes helpful, especially in patients with a large papular variety of PMLE. A good-to-excellent response was reported by 68.9% of the patients who received hydroxychloroquine and by 63% of the patients who received chloroquine. [57]
Beta-carotene, which is effective in erythropoietic protoporphyria, may be an alternative to chloroquine. Oral carotenoid preparation (beta-carotene and canthaxanthin in a daily total dose of 100 mg) was compared to hydroxychloroquine (200 mg qd). [58] Both offered full sun tolerance in an equal but small percentage of patients when compared to a placebo.
Azathioprine was reported to be effective in two cases of recalcitrant severe disease at 0.8-2.5 mg/kg/d for 3 months. [59] In one patient, the effect lasted up to 4 months after the discontinuation of therapy. However, the limited available data and azathioprine toxicity should necessitate extreme caution if choosing this form of treatment.
Other therapies like cyclosporine can be helpful, but further studies are needed to determine their benefits. [14]
Interest in the use of thalidomide for a number of dermatoses (eg, Behçet syndrome, cutaneous lupus, porphyria cutanea tarda, PMLE) is reemerging. The immunomodulatory action on subsets of T cells was proposed. Thalidomide (50-200 mg PO qhs) has reportedly been very effective for Native American patients with PMLE. The most commonly described adverse effects with thalidomide are sedation, constipation, and weight gain. The most serious complications of thalidomide therapy are peripheral neuropathy and teratogenicity.
Polypodium leucotomos, a tropical fern extract, was found to be helpful in delaying PMLE symptoms. The dose ranged from 720-1200 mg daily based on weight. It was protective in 30% and 28% of patients for UVA and UVB induced PMLE, respectively. [60, 61]
Afamelanotide helps in symptoms of PMLE by increasing the pigment in the skin, and it could be photoprotective for some patients. [62] Afamelanotide is injected subcutaneously at a dose of 20 mg, with slow release. This leads to increase in melanization in sun-exposed skin.
Prevention
Avoiding sunlight during the hours of most intense UV irradiation (from 10 am to 2 pm) and wearing protective clothing (eg, hats, gloves, long pants, long sleeves) should be emphasized to polymorphous light eruption (PMLE) patients. Blue denim clothing is particularly beneficial in terms of sun protection. Wide-spectrum sunscreens with a high SPF and UVA protection should be applied and reapplied during the day. The inclusion of both ecamsule and avobenzone in one preparation of sunscreen provides clinical benefit to patients with PMLE compared with sunscreens containing either ecamsule or avobenzone alone; each UVA filter individually. [48]
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Photograph of a springtime eruption of polymorphous light eruption in a 6-year-old boy. The eruption has occurred in the spring since the patient was aged 5 years, and it resolves completely with no scarring by mid to late summer. High block sunscreens attenuate but do not prevent the eruption. No itching or pain occurs. Courtesy of Dr. Jeremy F. Harrison, FRCA, FFAEM.
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Polymorphous light eruption on the thighs and hand. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/reactions/pmle2.jpg).
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Polymorphous light eruption on the chest. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/_resampled/FitWzY0MCw0ODBd/WatermarkedWyIyNTg0MSJd/pmle-14.jpg).
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Polymorphous light eruption on the chest. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/_resampled/FitWzY0MCw0ODBd/WatermarkedWyIyNTg0MCJd/pmle-15.JPG).
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Polymorphous light eruption on the arm. Courtesy of Waikato District Health Board and DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/_resampled/FitWzY0MCw0ODBd/WatermarkedWyIyNTg0MCJd/pmle-22.JPG).
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Polymorphous light eruption pathology showing papillary dermal edema. Courtesy of DermNet New Zealand (https://www.dermnetnz.org/assets/Uploads/pathology/e/pmle-figure-1.jpg).
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Polymorphous light eruption pathology showing papillary dermal edema. Courtesy of DermNet New Zealand (https://www.dermnetnz.org/assets/Uploads/pathology/e/pmle-figure-2.jpg).
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Polymorphous light eruption pathology showing papillary dermal edema with lymphocytes in the epidermis (exocytosis). Courtesy of DermNet New Zealand (https://www.dermnetnz.org/assets/Uploads/pathology/e/pmle-figure-3.jpg).
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Polymorphous light eruption pathology. The infiltrate is mainly lymphocytic but there may be intermixed eosinophils, neutrophils, and histiocytes. Courtesy of DermNet New Zealand (https://www.dermnetnz.org/assets/Uploads/pathology/e/pmle-figure-4.jpg).
