UVA.

UVA causes immediate and delayed tanning and contributes little to erythema and burning. It is constant throughout the day and throughout the year. The longer wavelengths of UVA can penetrate more deeply, reaching the dermis and subcutaneous fat. Chronic exposure to UVA radiation causes the connective tissue degeneration seen in photoaging, photocarcinogenesis, and immunosuppression. Photocarcinogenesis is augmented in patients who are immunosuppressed for organ transplantation. UVA augments the carcinogenic effects of UVB. UVA penetrates window glass and interacts with topical and systemic chemicals and medication. It produces photoallergic and phototoxic reactions.

UVB.

UVB produces the most harmful effects and is greatest during the summer. Snow and ice reflect UVB radiation. UVB delivers a high amount of energy to the stratum corneum and superficial layers of the epidermis and is primarily responsible for sunburn, suntan, inflammation, delayed erythema, and pigmentation changes. It produces tanning more efficiently than does UVA. Chronic effects include photoaging, immunosuppression, and photocarcinogenesis. It is most intense when the sun is directly overhead between 10 AM and 2 PM. UVB is absorbed by window glass. Prior exposure to UVA enhances the sunburn reaction from UVB.

UVC.

UVC is almost completely absorbed by the ozone layer and is transmitted only by artificial sources such as germicidal lamps and mercury arc lamps.

Sunlight–Skin Interaction.

DNA is mutated by UVB. Absorption of UVA leads to the release of reactive oxygen species that cause oxidation of lipids and proteins that affect DNA repair, produce dyspigmentation, and cause photoaging and carcinogenesis.

Aging Versus Sun Damage.

Sun exposure is the major cause of the undesirable skin changes often inaccurately perceived as aging. These changes, known as photoaging, are caused primarily by repeated sun exposure and not by the passage of time. Many of the clinical signs attributed to aging are actually manifestations of solar damage. The two processes are biologically different. The difference can best be demonstrated to patients by comparing the appearance of the skin under the arm near the axillae with the sun-exposed surface of the lower arm.

Normal Aging.

The skin begins to show signs of aging by ages 30 to 35. Aged skin is thin, fragile, and inelastic. The epidermis becomes thin. There is a gradual loss of blood vessels, dermal collagen, fat, and the number of elastic fibers. There is a reduction in the density of hair follicles, sweat ducts, and sebaceous glands, resulting in a reduction in perspiration and sebum production. Potent steroids should not be used on aged skin with few blood vessels because the steroids are not cleared from the skin as easily as in younger persons.

The skin becomes atrophic and fragile when subcutaneous tissue is lost. Elastic fibers are responsible for the elasticity and resilience of the skin. In normal aging, there is loss and fragmentation of elastic fibers, which result in fine wrinkles that resemble crumpled cigarette paper. These shallow wrinkles disappear by stretching. The skin is easily distorted, but it recoils slowly.

Photoaging.

Photoaging refers to those skin changes superimposed on intrinsic aging by chronic sun exposure ( Box 19.4 ). Unprotected, chronically exposed children can acquire significant actinic damage by the time they reach age 15. The effects of this damage may become apparent after age 20. Sun-damaged skin is characterized by elastosis (a coarsening and yellow discoloration of the skin), irregular pigmentation, roughness or dryness, telangiectasia, atrophy, deep wrinkling, follicular plugging, and a variety of benign and malignant neoplasms. The epidermis thickens. Although many different cells are affected, it is the elastotic material that accounts for the most striking effects of sun damage.

Solar elastosis is a sign highly characteristic of severe sun damage ( Figs. 19.1 and 19.2 ). There is massive deposition in the upper dermis of an abnormal, yellow, amorphous elastotic material that does not form functional elastic fibers. This altered connective tissue does not have the resilient properties of elastic tissue.

Solar elastosis. Numerous yellowish globules in the dermis can be seen through the thin, atrophic epidermis.

Nodular solar elastosis. A–B, Benign pink papules due to sun damage, may appear similar to a nonmelanoma skin cancer.

Wrinkling becomes coarse and deep rather than fine, and the skin is thickened ( Fig. 19.3 ). These wrinkles do not disappear by stretching. Sun-induced wrinkling on the back of the neck shows a series of crisscrossed lines ( Fig. 19.4 ) that form a rhomboidal pattern (cutis rhomboidalis nuchae).

Leathered wrinkling is a sign of severe sun damage.

Reactive hyperplasia of melanocytes causes lentigines on the upper back. Diffuse persistent erythema is most prominent in fair-skinned people. Sun-induced wrinkling on the back of the neck shows a series of crisscrossed lines (cutis rhomboidalis nuchae).

Reactive hyperplasia of melanocytes causes persistent pigmentation in the form of freckles, lentigines, and irregular hyperpigmentation and hypopigmentation on the hands, forearms, legs, chest, back, and neck ( Figs. 19.4 and 19.5 ).

Reddish brown, reticulate pigmentation with atrophy and telangiectasia is seen on the sides of the neck. This is referred to as poikiloderma of Civatte.

Chronic sun exposure disrupts the maturation of keratinocytes, causing scaling, roughness, seborrheic keratosis ( Figs. 19.6 to 19.9 ), actinic keratosis, actinic cheilitis, and squamous cell carcinoma.

Sun damage. Weathering nodules. Nodules on the helices of the ears are associated with age and chronic light exposure.

Sun damage. Sun damage causes lower lip atrophy with loss of normal skin lines.

Sun damage. Variations in pigmentation and diffuse actinic keratosis may occur after years of sun exposure.

Weathering nodules. Small yellow nodules along the outside rim of the helix due to chronic sun exposure.

Blood vessels diminish in number, and the walls of the remaining vessels become thin. Blood vessels need connective tissue for support. Bleeding occurs with the slightest trauma to the sun-damaged surfaces of the forearms and hands but not to the unexposed surfaces. Haphazard scarring may follow ( Figs. 19.10 and 19.11 ). Making patients aware of this difference convinces them that they do not have a platelet abnormality.

Sun damage. Fragile sun-damaged skin is easily torn and heals with haphazard scars called stellate pseudoscars.

Sun damage – purpura. Bleeding of the forearms and hands. Bleeding occurs with the slightest trauma to the sun-damaged surfaces.

Comedones form about the eyes ( Fig. 19.12 ).

Sun damage. Actinic comedones may become very large and can easily be expressed with a comedone extractor. This is referred to as Favre-Racouchot syndrome.

Prevention of Skin Aging.

A study of sunscreen use was performed. Participants assigned to daily sunscreen use applied sunscreen at least 3 to 4 days each week. Those in the daily-use group were less likely to have increased skin aging after 4.5 years than were those in the control group.

Topical Treatment.

Topical treatments have the following characteristics:

• 1.
  

  They are noninvasive.

  
  
• 2.
  

  They are slow to produce changes (latency period is 3 to 6 months).

  
  
• 3.
  

  Maintenance of improvements requires continued use.

  
  
• 4.
  

  Medication is expensive.

Topical Tretinoin and Tazarotene.

Topical retinoids provide some reversal of photodamaged skin ( Box 19.5 ). Objective improvements in wrinkling are seen after 3 to 6 months. Dyspigmentation (brown spots and mottled hyperpigmentation), surface roughness, and fine wrinkles respond best. The greatest response to therapy occurs during the initial 6 to 9 months.

Repeated applications of retinoids produce a skin reaction resembling irritation. This reaction is characterized by redness and desquamation, signs that correspond histologically to alterations in the stratum corneum and epidermal hyperplasia. Initially patients experience skin tightening and a pink glow. This smoothening occurs within 1 to 2 weeks of treatment. It is the first sign of improvement, and it occurs because the stratum corneum is thinner and more compact, and the epidermal layer is thicker and spongiotic. Increased proliferation of basal keratinocytes eventually doubles the epidermal thickness.

Collagen formation is reduced in photoaged skin and is partly responsible for wrinkle formation. Tretinoin and tazarotene increase collagen levels in photoaged skin; the end result is wrinkle effacement. Effacement of fine wrinkles occurs after 3 to 4 months of tretinoin therapy. The deepest, coarse facial wrinkles are still evident. Despite continued improvement in wrinkle effacement, the epidermal histology reverts to the pretherapy state.

Hyperpigmented lesions are a predominant component of photoaging in Chinese and Japanese persons; tretinoin cream lightens the hyperpigmentation of photoaging in these patients. Tretinoin therapy for individuals with darker skin pigmentation is safe. Postinflammatory dyspigmentation at sites of retinoid dermatitis does not occur in black and Asian patients.

Retinoid Application Procedures.

The response to retinoids may be dose dependent; higher concentrations may be more effective. Many patients experience a “retinoid dermatitis” with erythema and peeling. To achieve maximum clinical improvement of photoaged skin, it is not necessary to push retinoid use to the point that brisk retinoid dermatitis develops. A 48-week regimen of once-daily treatment with medication, followed by treatment three times weekly for an additional 24 weeks, maintains and, in some cases, even enhances the improvements in photoaged skin. Treatment on a once-a-week basis with retinoids is less effective in sustaining the clinical improvement achieved by the initial treatment regimen of tretinoin on a once-daily basis. Some reversal of the beneficial effects of tretinoin treatment is observed after discontinuation of therapy for 24 weeks, which indicates the need to continue tretinoin therapy to maintain clinical improvement.

Begin with nighttime application. Start treatment with cream-based tretinoin (0.025%), emollient-based tretinoin, or cream-based tazarotene. A gradual introduction to treatment using every-other-day application is appropriate for patients with sensitive skin (usually type I; Table 19.2 ), followed by more frequent applications when patients accommodate. Apply moisturizing cosmetics or lubricating lotions if dryness occurs. Maximum response occurs after 8 to 12 months of treatment; thereafter application frequency should be reduced to three or four times a week to maintain improvement.

Sun Protection During Use.

Encourage the daily use of sunscreens. Increased “photosensitivity” during tretinoin use is not an accelerated sunburn response. No increased risk of photocarcinogenesis has been detected in humans.

Tretinoin Use and Pregnancy.

The data on routine clinical use of topical tretinoin indicate that there is no increased risk during pregnancy. However, spontaneous malformation of the fetus occasionally occurs in “normal” pregnancies. It may therefore be prudent to postpone tretinoin therapy for patients who are actively trying to conceive, to avoid wrongful blame for congenital defects that may occur by chance. Tazarotene cream is a pregnancy category X medication and is contraindicated during pregnancy.

Estrogen Replacement.

Statistically significant reductions in dry skin and skin wrinkling occur with estrogen replacement.

Suntan.

A tan protects the body from photoinjury, but UV-induced injury must occur to produce a tan. Therefore intentional suntanning is unwise. Repeated brief exposures sufficient to induce tanning add to long-term damage. For a given individual, the deeper the tan, the more skin damage is sustained in achieving the tan.

Tanning follows moderate and intense sun exposure and occurs in two stages. The first stage, immediate pigment darkening (IPD), is caused primarily by UVA. The skin becomes brown while exposed but fades rapidly after exposure. IPD is caused by a photochemical change in existing melanin, not by an increase in melanin. A lasting tan requires the synthesis of new melanin; a more lasting tan becomes visible within 72 hours.

Tanning Parlors.

Artificial and natural UV sources will damage the skin to a similar degree and hence carry the similar photoaging effects and skin cancer risks. Artificial UV sources from tanning parlors are capable of delivering large amounts of radiation in a short amount of time, thereby increasing the risk of nonmelanoma and melanoma skin cancer.

Sunburn.

Forty-three percent of white U.S. children experienced one or more sunburns during the year. The sunburn reaction occurs in stages. With sufficient exposure, erythema appears within minutes (immediate erythema), fades, and then reappears and persists for days (delayed erythema). Vascular permeability of varying degrees results in edema and blisters. Desquamation occurs within a week. Systemic and topical corticosteroids have little or no clinically important effect on the sunburn reaction. Systemic and topical nonsteroidal antiinflammatory drugs (NSAID), when used at dosages to achieve optimal serum levels for antiinflammatory effect, only result in an early and mild reduction of UVB-induced erythema. Sunburn is best treated with cool, wet compresses. Topical anesthetic preparations that contain lidocaine provide some relief. Benzocaine, incorporated into some sunburn preparations, is a sensitizer and should be avoided. Protection with sunscreens can, if used properly, prevent burning in even fair-skinned individuals.

Methods of Sun Protection.

Natural protection is provided by the stratum corneum and the skin pigment melanin. People vary widely in their natural ability to tan or burn. A sun-reactive skin typing system has been devised to classify individuals according to their ability to tan or burn. These categories (see Table 19.2 ) are useful guides for devising programs for sun protection.

Recommendations for minimizing sun exposure are listed in Box 19.6 . Sunburns are particularly harmful, and great emphasis should be placed on preventing burns. Patients frequently relate that permanent freckling occurred on the upper back after one severe burn. Winter vacations in hot sunny climates appear to be very damaging, if the skin is burned. Total sun exposure during a lifetime is greatest on the face, back of the neck, bald head, upper chest, forearms, backs of the hands, and exposed lower legs. The effects of sunlight can readily be appreciated by comparing the lateral (sun-exposed) surfaces with the medial (sun-protected) surfaces of the forearms of older individuals.

Clothing.

Clothing is the best protection. Weave tightness and fabric type determine the potential for photoprotection. Stretched or wet fabric is less effective. Darker colors provide greater protection than lighter colors. Some manufacturers market special clothing with sun protection factor (SPF) ratings, including Solumbra (Sun Precautions, Seattle, WA, www.sunprecautions.com ).

Protecting the Young.

Significant sun exposure occurs during the early years of life when children spend hours playing outside. A study showed that regular use of a sunscreen with an SPF of 15 during the first 18 years of life reduces the lifetime incidence of basal and squamous cell carcinoma by 78%. All children should be protected with high-number SPF sunscreens. One-piece bathing suits that cover the trunk, upper arms, and legs are ideal for children.

Sunscreens.

Sunscreens are topical agents that protect the skin from UV light. Guidelines for their application are listed in Box 19.6 . Sunscreens should not be used as a means of allowing more time in the sun; this negates their beneficial effects.

Sunscreens are topical agents that absorb, scatter, or reflect ultraviolet radiation (UVR) and visible light. UVA agents absorb radiation in the spectral range of 320 to 400 nm. UVB agents absorb radiation in the range of 290 to 320 nm ( Fig. 19.13 ). Food and Drug Administration (FDA)-approved active sunscreen ingredients are listed in Tables 19.3 and 19.4 . The proper use of sunscreen can prevent the development of melanoma.

Absorption spectra of sunscreen components. UVA, ultraviolet A; UVB, ultraviolet B.

Sunscreen Labeling.

The term “broad spectrum” may appear on the product if FDA criteria are met. Labels can only contain either the statement “water resistant (40 minutes)” or the statement “very water resistant (80 minutes).” This claim is to be placed at the front of the product package. The time stated on the label reflects the actual water-resistant testing that is required to be done: SPF value needs to be determined after test subjects are immersed in a whirlpool for 2 times 20 minutes or 4 times 20 minutes.

User Application Amounts.

Sunscreen SPFs are determined by testing at an application density of 2 mg/cm ² . Typical application densities by most consumers range from 0.5 to 1 mg/cm ² . Therefore the actual protection received is often substantially less than that promised by the label. Encourage people to apply a substantial amount of product at least every 2 hours to obtain maximum benefit. High-SPF (50 SPF) sunscreens may provide more adequate protection even when applied by consumers in inadequate amounts.

Physical Sunscreens.

Physical sunscreens (referred to as inorganic or nonchemical sunscreens) are composed of particles that scatter and reflect light. Physical blocking agents, such as zinc oxide and titanium dioxide, are composed of particles of a size that scatter, reflect, or absorb solar radiation. Twenty percent zinc oxide, or 20% titanium dioxide, reduces transmittance in the UVA and visible ranges to a maximum of approximately 20%. Newer micronized preparations that are suspensions are more cosmetically acceptable.

Chemical Sunscreens.

Chemical sunscreens (organic agents) absorb radiation. Newer broad-spectrum chemical sunscreens include a combination of chemicals that absorb both UVB and UVA radiation.

Water-Resistant Sunscreens.

Substantivity is the characteristic of a sunscreen that reflects how effectively the advertised degree of protection is maintained under adverse conditions, including repeated water exposure or sweating. According to the FDA, a sunscreen is declared water-resistant if it can maintain its original SPF after two 20-minute immersions. A sunscreen is very water-resistant if it retains its protective integrity after four 20-minute immersions.

Sun Protection Factor.

The effectiveness of sunscreens is expressed as the SPF. The SPF is defined as the ratio of the least amount of UVB energy (minimum erythema dose) required to produce a minimum erythema reaction through a sunscreen product film to the amount of energy required to produce the same erythema without any sunscreen application. For an individual who wears a sunscreen with an SPF of 15, 15 times longer than usual is required to develop erythema. The SPF for commercially available products is derived from tests with application of a uniform amount of sunscreen that is thicker than most individuals routinely use. A substantial amount of sunscreen must be applied to obtain a full SPF rating.

Choice of Sunscreen Strength.

A sunscreen with an SPF of 30 or greater is recommended under most conditions. Sun protection does not increase proportionally with the designated SPF. In the higher range of SPFs, the differences become less meaningful. An SPF of 15 indicates 93% protection; an SPF of 34 indicates 97% protection. Newer sunscreens contain Mexoryl or Helioplex. Avobenzone is one of the best UVA absorbers, while oxybenzone is a very good UVB absorber with some UVA absorbency. Together with the Helioplex or Mexoryl SX stabilizing technology, these two sunscreen ingredients complement each other for high, broad-spectrum, and photostable coverage.

Frequency of Use.

The majority of lifetime sun exposure occurs during multiple brief exposures that are not intended to produce tanning; therefore daily sun protection should be encouraged. People who sunburn easily or those who have light complexions or sun-sensitivity disorders should use a high SPF sunscreen every day, all year, particularly if they live in more equatorial latitudes. Sunscreens should be applied once in the morning and reapplied every 2 hours or after swimming and heavy exercise. Encourage people to have sunscreens available in the bathroom and to make morning application part of their daily ritual. Sunscreen may fail to prevent sunburn if it is washed off during swimming or if it is not applied to all exposed skin. The protection against sunburn afforded by a reapplication of sunscreen relative to a single application is significant. Compared with the first application, the second sunscreen application affords 3.1 times more protection against minimal UVR-induced erythema. The combined effect of two sunscreen applications gives 2.5 times better protection from UVR than does a single sunscreen application.

Glass Filters.

Glass filters UVB radiation but transmits UVA radiation. Protective coatings applied to glass can block UVA radiation. LLumar window film ( www.llumar.com ) is a microthin film that is installed onto home and automobile glass surfaces to provide solar protection. It blocks 99% of the UV rays. Glass filters are indicated for patients with multiple skin cancers, transplant patients with skin cancers, and patients with photosensitive dermatoses.

Adverse Reactions to Sunscreens.

Allergic reactions to preservatives or fragrances occur more frequently than to the active ingredients. Irritation to creams is much more common than allergy to a component. Burning or stinging may be experienced in the eye area. Sunscreen active ingredients may cause photocontact allergic reactions. Most patients who develop photocontact dermatitis to sunscreens are patients with photodermatides.

Vitamin D Levels.

Sun protection is important to prevent skin malignancies. Vitamin D is formed in the skin through the action of the sun. Vitamin D deficiency may induce various types of cancer, bone diseases, autoimmune diseases, hypertension, and cardiovascular disease. Strict sun protection can cause vitamin D deficiency, although there is no evidence that normal sunscreen use results in vitamin D deficiency. Vitamin D status can be measured. Balanced recommendations on sun protection have to ensure an adequate vitamin D status. Twenty minutes of exposure each day to an area the size of the trunk may be reasonable until guidelines are established.

Sunless or Self-Tanning Lotions.

Sunless or self-tanning lotions contain dihydroxyacetone (DHA), which darkens the skin by staining. The preparations are nontoxic. The site of action of DHA is the stratum corneum. Staining of skin occurs when DHA combines with free amino groups in skin proteins (keratin) in the stratum corneum to form brown products called melanoidins. Little to no sunscreen protection is provided by their use. Some products are formulated with standard sunscreens.

The newer preparations do not produce the orange color that occurred from the older formulations.

Etiology.

The precise underlying mechanism of PMLE is not known. Patients with PMLE may not develop the normal cutaneous immune suppression, seen after UVR exposure. When the skin is exposed to UVR, cells are altered at the DNA and protein level. These organic cellular alterations may be recognized by the immune system as foreign, eliciting the autoimmune reaction seen in PMLE. Normal individuals do not likely react to these altered cellular components because their skin has been locally immunosuppressed by UVR ( Fig. 19.14 ).

Abnormal cell migration patterns in polymorphous light eruption (PMLE). Exposure to UVR leads to decreased neutrophil infiltration into the skin of patients with PMLE compared with healthy subjects. This lack of neutrophil infiltration (caused by decreased chemoattraction) is associated with reduced IL-4 and IL-10 production and release. In addition, mast cell infiltration is inhibited, whereas LCs are resistant to UV-induced migration triggers. Overall, this results in a nonimmune suppressive cutaneous microenvironment and subsequent DTH response to photoantigens in patients with PMLE but not healthy subjects. CXCR4, C-X-C motif receptor 4; DTH, delayed type hypersensitivity; IL, interleukin; UVR, ultraviolet radiation; VDR, vitamin D receptor.

(From Gruber-Wackernagel A, Byrne SN, Wolf P. Polymorphous light eruption: clinic aspects and pathogenesis. Dermatol Clin 2014;32(3):315–34, viii.)

Hereditary PMLE (Actinic Prurigo).

Hereditary PMLE eruption occurs in the Inuit of North America and in Native Americans of North, Central, and South America. Its transmission appears to be autosomal dominant with incomplete penetrance and variable expressivity. In northern latitudes, the eruption appears on sun-exposed areas of the body as early as March and persists through October. The face is the most commonly involved area. Intensely itchy papules, plaques, and nodules, along with excoriations and scars, are present on the sun-exposed area ( Fig. 19.15 ). The onset is usually in childhood. The majority of patients are sensitive to UVA light. The younger ages of onset (up to 20 years of age) are associated with cheilitis and more acute eruptions and are more likely to improve over 5 years. Those who develop actinic prurigo as adults (21 years of age and older) tend to have a milder and more persistent dermatosis.

Actinic prurigo. Erythematous papules have coalesced to form a plaque on the right cheek, V of the neck, and extensor surfaces of both distal arms and forearms of an 8-year-old girl.

(From Chantorn R, Lim HW, Shwayder TA. Photosensitivity disorders in children: part I. J Am Acad Dermatol 2012;67(6):1093 e1–18; quiz 1111–2. )

Clinical Presentation.

Women are affected more often than are men. The mean age at onset is 34 years (5 to 82 years). For men the mean age is 46 years and for women, 28 years. The most common initial symptoms are burning, itching, and erythema. The eruption usually lasts for 2 or 3 days, but in some cases it does not clear until the end of summer. Many patients experience malaise, chills, headache, and nausea starting approximately 4 hours after exposure but lasting only 1 or 2 hours. The most commonly involved areas are the V of the chest (the area exposed by open-necked shirts), the backs of the hands, the extensor aspects of the forearms, and the lower legs of women. Reports vary about the wavelength of light responsible for inducing lesions. The wavelength of light necessary to elicit the eruption varies with each patient. Many react to UVB, others to UVA, or some to both.

Clinical Subtypes.

There are a number of clinical types of PMLE.

Papular Type.

The papular type is the most common form ( Figs. 19.16 and 19.17 ). Small papules are disseminated or densely aggregated on a patchy erythema. A pinpoint papular variant has been described.

Polymorphous light eruption. A, Papular type. B, Plaque type.

Polymorphous light eruption in a child. A–B, Pruritic pink papules occurring on the arms.

Plaque Type.

The plaque type is the second most common pattern. Plaques may be superficial or urticarial. They may coalesce to form larger plaques and at times are eczematous ( Figs. 19.18 and 19.19 ).

Polymorphous light eruption. Plaque type.

Polymorphous light eruption. Pruritic papules and plaques on sun-exposed areas. This rash is more common with the first sun exposure and lessens with repeated exposure. The rash will resolve in 10 days to 2 weeks after sun exposure.

Papulovesicular Type.

The papulovesicular type is less common. It occurs primarily on the arms, lower limbs, and V area of the chest and usually begins with urticarial plaques from which groups of vesicles arise ( Fig. 19.20 ). Itching is common and is usually moderate or marked. This form occurs almost exclusively in women.

Polymorphous light eruption. Papulovesicular type.

Eczematous Type.

Erythema, papules, scale, and sometimes vesicles occur. Eczematous lesions occur almost exclusively in men.

Erythema Multiforme Type.

Erythema multiforme–type lesions and distribution are similar to those of classic erythema multiforme, with lesions most frequent on the backs of the hands and extensor forearms.

Hemorrhagic Type.

The hemorrhagic type may first appear as hemorrhagic papules or purpura. This form is rare.

Spring and Summer Eruption of the Elbows.

Pruriginous, erythematous–edematous papules and plaques are located on both elbows.

Differential Diagnosis.

The papular form resembles atopic dermatitis. PMLE is less pruritic and occurs in a sun-exposed distribution, not in crease areas, as does atopic dermatitis.

Systemic and discoid lupus erythematosus plaque–like lesions and histologic features may be identical to those of PMLE. The characteristic direct and indirect immunofluorescence patterns of lupus erythematosus clarify the diagnosis.

Diagnosis.

The histologic features are not diagnostic. Immunofluorescence is negative. Phototesting is not essential but, when performed, must include both UVB and UVA testing.

Topical and Oral Steroids.

Short, intermittent 3- to 14-day courses of group I to V topical steroids are effective. Group II through V topical steroids reduce pruritus and hasten resolution. Short courses of oral steroids are useful for very itchy, widespread eruptions or for patients who flare during a course of phototherapy or photochemotherapy.

Protection.

Sun exposure during times of maximum intensity (between 10 AM and 2 PM) should be avoided. Sunscreens with maximum sun-protecting factors should be used. The most sensitive patients are advised about filters for car windows (LLumar UV shield, www.llumar.com ) and fluorescent lighting at home.

Desensitization With Phototherapy.

The sensitivity of human skin to UV radiation decreases after exposure to UV radiation. Adaptation occurs by exposing patients to small and controlled doses of light. Doses small enough not to cause any abnormal reaction but large enough to increase the tolerance of the skin to light are used. A regular series of such exposures, with small increments in exposure time, can result in an appreciable tolerance. Increments of 10% per exposure are given as long as there are no adverse reactions. This is the so-called phenomenon of hardening. This practice is safe; therefore controlled exposure to sunlight or artificial UV light sources should be the first type of treatment. Patients treated with UVB or narrowband UVB (NB-UVB) in the dermatologist’s office receive five exposures per week for 3 weeks in the spring, with gradually increasing exposure doses. Hardening may also be accomplished with either UVA (340 to 400 nm) or UVA and UVB (300 to 400 nm) (10 exposures to UV light). Commercial “sun beds” are not recommended because they are most likely to provoke the PMLE rash. Prophylactic UVB may sometimes trigger the eruption, particularly in severely affected subjects, necessitating concurrent systemic corticosteroid therapy.

Psoralen UVA (PUVA).

Treatment can be acquired in the dermatologist’s office by using artificial UVA light and 8-methoxypsoralen (PUVA). A remission can be obtained for most patients by treatment two or three times each week for 4 to 12 weeks in the early spring. PUVA therapy protects temporarily, and repeated sun exposures are required to maintain protection. A number of patients remain protected for 2 to 3 months, even after pigmentation has faded. Topical steroids should be applied if the disease is activated by treatment. Maximum protection is reached 3 weeks after a 1 week course of treatment, and a single course offers a minimum of 6 weeks of protection. The course can be repeated each month during the spring and summer months if needed. Protective glasses such as NoIR should be worn for the remainder of the day after taking psoralens.

Antimalarial Drugs.

Antimalarial drugs may be effective and should be considered for patients who are not protected by sunscreens and do not respond to UVB or PUVA phototherapy. Antimalarials need to be used only during the summer months; therefore the total necessary dose is small. A 3-month trial (hydroxychloroquine 400 mg/day for the first month and 200 mg/day thereafter) has been effective in reducing rash and irritation. Although the risk of eye damage is slight, ophthalmologic examinations should be obtained periodically to monitor for antimalarial toxicity.

Other Treatments.

Beta-carotene is somewhat effective for prophylactic treatment of PMLE, but the skin turns yellow-orange. Only 30% of patients responded satisfactorily to a dosage of 3 mg/kg body weight continued throughout the summer. Cyclosporine or azathioprine may be used for rare severe disabling cases.