Introduction:
Photosensitivity dermatitis is an eczematous skin condition that occurs when exposed to sunlight or electromagnetic radiation. Ultraviolet radiation is believed to be the leading cause and can occur in all skin types. Therefore, the affected individuals stay away from sunlight and avoid certain forms of artificial light.
What Is Photosensitive Dermatitis and its Causes?
Photosensitive dermatitis is the inflammation of the skin when exposed to visible light or some types of artificial light. It can affect all ages and all skin types.
Several factors can cause photosensitivity dermatitis, such as:
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Photosensitivity eruptions that occur due to drugs.
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Contact photo irritant or an allergic reaction that is an allergic response that causes dermatitis.
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Idiopathic chronic photosensitivity dermatitis that occurs without any reason.
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Photoaggravated atopic dermatitis.
But the most common cause is believed to be ultraviolet radiation such as UVA, UVB, and visible light.
What Is Photosensitivity?
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Photosensitivity or sun allergy is a condition where exposure to sunlight can cause various symptoms and diseases.
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A rash or dermatitis that develops due to photosensitivity is called photodermatosis.
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If the rash resembles eczema, it is called photodermatitis.
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A photosensitizer is a chemical or drug that causes photosensitivity.
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A reaction to photosensitizer resembles an exaggerated sunburn.
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Photosensitivity can occur at any age and affects both genders.
What Are the Clinical Features of Photosensitivity Dermatitis?
Generally, areas exposed to the sun have skin eruptions or lesions; this phenomenon is described as photo-disturbed lesions. These areas include the arms, hand, back, neck, and chest. Sites that are not exposed to sunlight, such as upper eyelids, shadowed areas under the nose and chin, and web spaces between fingers, do not present these lesions.
These conditions resemble sunburns in appearance but can occur even with less exposure to sunlight.
The response can be immediate or delayed.
Areas that are frequently affected include:
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Face, except behind the ears, eyelids, under the nose, and hairline.
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Dorsum of hands, except the finger webs.
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Neck but does not affect the area under the chin.
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Feet are the area exposed to the sun; areas covered by footwear or straps of footwear can be unaffected.
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Forearms are cut off depending on the length of the sleeves worn.
Contact Photoirritant:
Photoallergic dermatitis or contact photo irritant is generally an allergic reaction to certain toxic substances. Certain chemicals or drugs can cause photosensitivity, and these agents are called photosensitizers.
These reactions appear as sunburn-like lesions and leave a deep pigmentation on the skin.
They present in the same fashion as chronic or acute dermatitis. This type of photosensitivity is diagnosed by patch testing or photo patch testing. Exposing duplicate sets of patches to UVA is called photo patch testing.
Common photo allergens or photo irritants include:
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Antiseptics in antibacterial soaps.
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Psoralens.
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Fragrances.
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Tar products.
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The photosensitizing nature of sunscreens has reduced as PABA is avoided in the formulations.
Drug-induced Photosensitivity:
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Photosensitivity can occur due to drugs, due to toxic and allergic mechanisms.
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Medications that cause sunburn-like reactions include:
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Tetracyclines.
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Retinoids.
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Nonsteroidal anti-inflammatory drugs.
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Chlorpromazine.
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Methoxsalen.
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Some drugs are known to cause allergic reactions, such as Sulfonylureas, Quinine, and Hydrochlorothiazide.
Chronic Photosensitivity Dermatitis:
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Chronic photosensitivity generally affects elderly men and is a rare condition.
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The skin that is exposed to the sun is thickened, itchy, and dry.
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It is found in areas such as the back of the hands, face, and neck.
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Biopsy shows reticulosis or T-cell lymphoma; therefore, it is also called actinic reticuloid.
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Even small exposure to sunlight, as little as 30 seconds, can cause a reaction. Small amounts of UVB, UVA, and severe cases of visible light can cause a reaction.
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Some cases may be preceded by exposure to contact allergy (such as plants like chrysanthemum), photosensitivity to a drug, or contact photoallergy.
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This is treated by immunosuppressive medications such as Azathioprine or systemic steroids.
Photo-aggravated Atopic Dermatitis:
In some cases, patients with atopic dermatitis can become photosensitive. The diagnosis is often delayed as the patients already have chronic dermatitis. In these cases, the photosensitivity can be extremely severe.
How to Diagnose Photosensitivity?
Chronic photosensitivity can be diagnosed using patch testing. If the patient has atopic dermatitis, this test will be negative.
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Idiopathic chronic photosensitivity dermatitis will show contact allergies.
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Photopatch Test:
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This is similar to patch tests. Two sets of antiseptics, perfumes, sunscreens, and plant materials are applied. One set is exposed to a small amount of ultraviolet light (UVA) (5J/cm2). If allergic, the following categories are noted:
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Contact Photo Aggravation: An area exposed to light has a higher reaction than an unexposed site.
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Contact Allergy: Reaction to the area exposed to light is the same as that of the unexposed site.
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Contact Photoallergy: Unexposed allergen does not have a reaction; however, exposed allergen shows a reaction.
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Phototests:
Gradual doses of monochromatic or broadband ultraviolet radiation are exposed to the skin; this is done to confirm the presence of systemic photosensitivity.
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Photo Provocation Tests:
This includes repeated three daily doses of one-and-a-half minimal erythema doses of broadband ultraviolet radiation; this is done in an attempt to reproduce a specific photodermatosis.
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Laboratory Tests: Skin biopsies and laboratory investigations can be done to confirm the diagnosis. Laboratory tests included antinuclear antibody (ANA) panels and porphyrin profiles.
How to Manage Photosensitivity?
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The management varies according to the skin condition.
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Contact photoallergy: known allergens should be avoided.
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Drug-induced photosensitivity: photosensitizers should be stopped.
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Emollients and topical steroids can be used to manage eczematous reactions.
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Severe dermatitis may require oral corticosteroids or immunosuppressive agents such as Azathioprine.
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Measures can be taken to protect oneself from exposure to sunlight, such as:
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Staying away from sun exposure at the peak of the day or middle of the day.
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Weaning broad hats, sunglasses, and covering the skin.
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Oral photoprotective medications such as antioxidants or Polypodium leucotomos.
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Broad-spectrum sunscreen should be applied liberally in areas exposed to the sun.
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Conclusion:
Photosensitivity dermatitis is an eczematous reaction to exposure to the sun. It can be due to contact allergy, idiopathic, or drug response. The areas exposed to the sun are affected, such as the face, hands, and neck. The management of the disease depends on the cause; topical or systemic steroids or immunosuppressive agents may be necessary in severe cases.
