3.C Photosensitivity -Chemically-induced Flashcards
Types of Photosensitivity disorders
Chemically-induced
Metabolic
Idiopathic
Light-exacerbated
Substances that induce an abnormal reaction in sun-exposed skin or equivalent light emitting source.
Photosensitizers
Difference between Phototoxicity and Photoallergy:
Phototoxicity:
- Anyone with exposure to photosensitizer and sunlight
- Sunburn-like
- Within the affected area only
- Onset : < 48h
Photoallergy: - In sensitized persons only -Contact dermatitis-like - Delayed Onset: up to 14 days -
Molecular weight of photosensitizers
Less than 500 Daltons
Specific wavelengths of light that evoke reaction
Action spectrum
Action spectrum of Photoxicity
320nm-425nm
What conditions precede photosensitivity
Sufficient
- Concentration of photosensitizer
- Intensity of light
- Duration of light
Onset of erythema in Phototoxicity
2-6 hours
worsens for 48-96 hours
Exposure of nail bed in phototoxicity results to
Photo-onycholysis
Phototoxicity due to Coal tar, creosate, crude coal tar or pitch
Phototoxic Tar Dermatitis
Skin type protected for hyperpigmentation in Phototoxic Tar Dermatitis
Types V and VI
Where is coal tar found?
Cosmetics Drugs Dyes Insecticide Disinfectant
Phototoxic reaction caused by Furocoumarins in plants.
Phytophotodermatitis
Inducers of Phytophotodermatitis
Fragrance with Bergapten
Berloque Dermatitis
Characteristics of Berloque Dermatitis.
Hyperpigmentation preceded by redness and edema on the Neck and Face.
Families of most phototoxic plants:
Umbelliferae
Rutaceae
Compositae
Moraceae
A phytophotodermatitis caused by contact with yellow-flowered meadow parsnip or a wild yellow-flowered herb of the rose family.
Dermatitis Bullosa Striata Pratensis
Characteristics of Dermatitis Bullosa Striata Pratensis
Streaks and bizarre configurations with vesicle and bullae.
Heals with residual hyperpigmentation
Common fruit that causes phytophotodermatitis
Lime
Difference of Blistering phytodermatitis to Rhus Dermatitis (Urushiol)
Blistering Phytodermatitis
- Sun-exposed sites
- Burning pain within 48h
- Marked hyperpigmentation results
Rhus Dermatitis
- Not limited to sun-exposed areas
- ITCHING prominent
- Duration: A week or more
Treatment of Phytodermatitis
- Cool compress
- Mild analgesics
- Topical emollients
Treatment of hyperpigmentation in Phytodermatitis
Tincure of time
Topical steroids and strict sun avoidance may protect againt hyperpigmentation
