Photodermatitis

By admin On Oct 23, 2023

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Photodermatitis

Allen Richburg

Basics

Photodermatitis is an abnormal skin reaction to light or ultraviolet (UV) rays.
The reaction may be acute or chronic, allergy-mediated, or irritative and often is associated with substances or conditions that create an increase in photosensitivity.

Description

Light-induced eruptions seen in a pattern of photodistribution on the skin
Exogenous:
- Phototoxic reactions (nonallergic): Result of acute toxic effect on skin by UV light alone (sunburn) or together with a photosensitizing substance; occurs in 100% if exposed to enough of the agent and light
- Photoallergic eruptions (allergic, delayed hypersensitivity): A form of allergic dermatitis resulting from combined effects of a photosensitizing substance (drugs or chemical) plus UV light
Endogenous:
- Porphyria cutanea tarda: Defect in uroporphyrinogen decarboxylase, inherited and acquired types
- Erythropoietic protoporphyria: Autosomal dominant deficiency in ferrochelatase, diagnosed in childhood
Idiopathic and immunologic:
- Polymorphous light eruption: Chronic, intermittent light-induced eruption with erythematous papules, urticaria, or vesicles owing to a certain threshold of UV light; presents in 20s and 30s; spring and summer most common
- Chronic actinic dermatitis: Lichenified papules or plaques on sun-exposed areas; pruritic; older adults
- Solar urticaria: IgE formation with mast cell degranulation; urticaria minutes after sun exposure; disappears within hours
Photoaggravated conditions:
- Lupus erythematosus
- Dermatomyositis
- Atopic dermatitis
- Seborrheic dermatitis
Ultraviolet (UV) radiation:
- Both UVA and UVB are responsible for photodermatitis (light-induced eruptions); therefore, both UVA and UVB should be blocked during outdoor sport activities.
- UVA range 320–400 nm: Penetrates skin deepest; can penetrate window glass; 360-nm wavelength is peak for many photosensitizing drugs.
- UVB range 290–320 nm: Penetrates skin superficially; responsible for most acute skin erythema

Epidemiology

Can affect patients from all backgrounds and races who are exposed to UV light
Most frequently identified photoallergens by photopatch testing: Medications, sunscreen agents, fragrances, and antiseptics

Incidence

Up to 29.7% of persons who use sensitizing agents will get a reaction.

Prevalence

Estimated 25% of white-skinned persons in the U.S. are Fitzpatrick skin type I or II and have an increased risk of sunburn with limited exposure.

Risk Factors

Fitzpatrick skin types:

Type I: Never tan, always burn
Type II: Occasionally tan, usually burn
Type III: Usually tan, occasionally burn
Type IV: Easily tan, rarely burn
Type V: Brown skin
Type VI: Black skin

Genetics

Skin types I and II will exceed sunburn threshold tolerance in 10–20 min of noontime-temperature summer sunlight.
3–8 times minimal erythema dose will produce moderate to severe burn.
Other genetic conditions increase risk (eg, xeroderma pigmentosa, porphyrias).

General Prevention

Avoid sun from 10 a.m. to 2 p.m. when 2/3 of total daily UV radiation reaches the earth.
Avoid being outdoors during high UV index days.
Avoid indoor tanning beds.
Use protective clothing: Long sleeves, wide-brim hats, sunglasses.
Use tinted glass windows.
Identify and avoid sun-sensitizing drugs and agents (see under “Causes”).
Sunscreens:
- No. 15 sun protection factor (SPF) or greater recommended
- Apply 30 min before exposure and every 2 hr, especially after sweating and swimming.
- 1 oz to cover whole body
- Physical blocking agents: Zinc oxide, titanium dioxide, iron oxide, kaolin
- Sunscreen with ingredients that filter out both UVA and UVB rays is recommended.
UVB filters:
- PABA derivatives
- Cinnamates
- Salicylates
- Octocrylene
UVA filters:
- Benzophenones
- Avobenzone (Parsol 1789)
- Anthranilates
Physical blocking agents:
- Iron oxide
- Kaolin
- Titanium dioxide
- Zinc oxide

Etiology

Exogenous photosensitizers:
- Antiarrhythmics
- NSAIDs
- Phenothiazines
- Diuretics
- Quinolones
- Tetracyclines
- Thiazides
- Sulfonamides
- Sulfonylureas
- Oral contraceptives
- Topicals: Psoralens, coal tars, photoactive dyes (eg, eosin, acridine orange)
Phytophotosenitizing agents:
- Citrus fruits (Rutaceae): Lemon, lime, grapefruit; furocoumarins are more concentrated in the peel.
- Fig (Moraceae)
- Cayenne pepper, paprika, chili, Tabasco (Solanaceae)
- Nettle (Urticaceae)
Photoallergens:
- Antiseptics
- Fragrances
- Medications
- Sunscreen filters

Diagnosis

History of previous sun or UV light exposure
Exposure to or ingestion of the many sun-sensitizing agents
Family history of similar disorders
Type of sunscreen and how the sunscreen has been used prior to reaction

Physical Exam

Phototoxic:
- Erythema
- With increasing severity: Vesicles and bullae
- Classic example: Sunburn
- Nails may exhibit onycholysis.
- Chronic: Epidermal thickening, elastosis, telangiectasia, and pigmentary changes
- Sharp lines of demarcation between involved and uninvolved skin (sunlight exposure)
- Phototoxic eruption owing to topicals: Area of application
- Usually develops shortly after sun exposure.
- Hyperpigmentation may follow resolution.
- Pain
Photoallergic:
- Papules with erythema and occasionally vesicles
- Area exposed to light with less distinct borders
- Usually delayed: 24 hr or more after exposure
- May spread to unexposed areas
- Pruritus
Polymorphous light eruption:
- Erythematous papules
- Occasionally urticaria or vesicles
- Scattered over sun-exposed areas with normal skin in between
- Can spread to nonexposed areas
- Often flares in spring or early summer
- Desensitization affect (less over the course of the summer)
- Burning or pruritus may precede lesions.
Chronic actinic dermatitis:
- Lichenified papules on sun-exposed areas in older person
- Usually pruritic
- Biopsy and phototesting confirm diagnosis.
Solar urticaria:
- Urticaria within minutes of UV exposure
- Unidentified photosensitizing agent
- Wheals itch and burn and disappear within hours.

P.465

Porphyria cutanea tarda:
- Skin fragility
- Blisters, crusts, milia
- Mottled skin pigmentation
- Hypertrichosis on periorbital area
Erythropoietic protoporphyria:
- Presents by age 2
- Child cries or screams in pain when exposed to sun
- Burning feeling, induration, and purpura
- Waxy thickening of skin on knuckles

Diagnostic Tests & Interpretation

Lab

Antinuclear antibody and other rheumatologic tests when systemic lupus erythematosus and dermatomyositis are suspected
Check serum, urine, and stool porphyrin if porphyria is suspected.
Drugs that may alter lab results: N/A
Disorders that may alter lab results: N/A

Diagnostic Procedures/Surgery

Photopatch test: Test a small patch of a potentially photosensitive substance on the skin to find out if this is the substance that caused the reaction. Examples of substances tested include medications, sunscreens or other lotions, fragrances, antiseptics, and plant products.
Phototest: Test the skin for a photoreaction to UV light after normal diet and/or after ingestion of a possible photosensitizing agent such as an NSAID, a sulfa drug, a diuretic, or an oral contraceptive pill.
Skin biopsy: Used to determine the type of skin inflammation and the potential disease process or malignancy

Pathological Findings

Lymphohistiocytic dermal infiltrates and spongiosis seen in the more common condition of phototoxicity

Differential Diagnosis

Phototoxicity
Photoallergic reaction
Cellulitis
Pityriasis rosea
Viral exanthem
Drug eruption
Polymorphorous light eruption
Chronic actinic dermatitis
Solar urticaria
Porphyria
Atopic dermatitis
Seborrheic dermatitis
Dermatomyositis
Systemic lupus erythematosus
Steven-Johnson syndrome

Treatment

Long-term treatment:
- Sun and light radiation protection and avoidance
- Identification and avoidance of photoenhancing, -sensitizing, and -allergic substances
Acute treatment: Outpatient

Medication

Drugs of choice for phototoxic and photoallergic reactions (1,2):
- Topical corticosteroids class I or II within 4–48 hr of exposure × 3 days (eg, betamethasone valerate 0.1% cream)
- NSAIDs, topical or oral (eg, indomethacin topical 5% or oral 25 mg t.i.d.; aspirin; others)
- Prednisone for severe reactions (0.5–1 mg/kg/d × 3–10 days)
- Antihistamines for pruritus (eg, hydroxyzine 25–50 mg q.i.d.)
- Sunscreens for prevention: Use broad-spectrum sunscreen to block both UVA and UVB.
Treatment for polymorphous light eruption:
- Desensitization with UVB or UVA (PUVA) phototherapy for 15 min 2–3 × per week during the spring
- Antimalarial drugs for protections during the spring and summer
- Topical or oral steroids once the outbreak has occurred
Treatment for chronic actinic dermatitis:
- Topical and oral corticosteroids
- Topical tacrolimus
- Low-dose PUVA
- Mycophenolate mofetil
- Cyclosporine
- Azathioprine
Treatment for solar urticaria:
- Antihistamines
- Low-dose PUVA
Treatment for porphyria cutanea tarda:
- Phlebotomy
- Avoid hepatotoxins and iron.
- Antimalarial drugs
Treatment for erythropoietic protoporphyria:
- β-Carotene
- Narrow-band UVB
- PUVA
Contraindications: Refer to manufacturer's profile for each drug.
Precautions: para-Aminobenzoic acid (PABA), benzophenones, and cinnamates may cause contact dermatitis. Also, if allergic to benzocaine, procaine, paraphenylenediamine, or sulfonamides, one may have allergy to PABA. Refer to manufacturer's profile for each drug.
Significant possible interactions: Refer to manufacturer's profile for each drug.

Additional Treatment

General Measures

Avoid sunlight/limit exposure.
Protective clothing/sunscreens
Ice packs/cold water compresses

Ongoing Care

Follow-Up Recommendations

Avoid sunlight.

Patient Monitoring

Monitor as necessary for persistence or recurrence.

Diet

No special diet

Patient Education

Avoidance of sunlight
Avoidance of photosensitizing drugs
Protective clothing
Use sunglasses that wrap around and absorb UVA and UVB rays.
Use lip balm sunscreens.
Sunscreens:
- SPF 15–30 with both UVA and UVB protection
- Apply 15–30 min before exposure.
- Reapply generously every 1–2 hr and especially after swimming or sweating.
- Stress application to be sure to cover neck and ears (one study showed that 60% of people miss these areas).
- Children:
  - Avoid midday sun.
  - For those younger than 6 mos of age, use titanium dioxide, which is less likely to irritate the skin.

Prognosis

Good with avoidance/protection measures

Complications

Geriatric Considerations

Geriatric: More likely to experience adverse reactions to causative drugs.

References

1. Arndt KA, Hsu JTS. Sun reactions and sun protection. In: D'Amelio Miller, ed. Manual of dermatologic therapeutics. Lippincott Williams & Wilkins, 2007:212–221.

2. Hall JC. Dermatologic reactions to ultraviolet radiation and visible light. In: Linden L, Lim HW, eds. Sauer's manual of skin diseases. Lippincott Williams & Wilkins, 2006:364–372.

Additional Reading

Fitzpatrick TB, et al. Color atlas and synopsis of clinical dermatology: common and serious diseases, Second ed. McGraw-Hill, 1992:210–213.

McKee PH, Calonje E, Granter SR. Pathology of the skin: with clinical correlations, Vol 1, 3rd ed. Elsevier Mosby, 2005:630–633.

Scalf LA, Davis MD, Rohlinger AL, et al. Photopatch testing of 182 patients: a 6-year experience at the mayo clinic. Dermatitis. 2009;20:44–52.

Tyring SK, Lupi O, Hengge UR. Tropical dermatology. Elsevier Inc., 2006:441–443.

Codes

ICD9

692.72 Acute dermatitis due to solar radiation