10 - Photosensitive Disorders Flashcards
Three groups of UV light:
UVA (320-400nm)
UVB (290-320nm)
UVC (100-290nm)
UVA
Constant throughout the day/year
Long waves penetrate deeply - dermis, subcutaneous fat
Chronic exposure -> CT degeneration, photoAging and photoAllergic
UVB
Greatest during the summer - most harmful waves
High amount of energy to corneum / superficial layers
Sunburn/tan, erythema, pigmentation, inflammation
UVC
Absorbed by the ozone layer
Transmitted only by artificial sources -> germicidal lamps
Photobiologic Skin Types
Slide 6
Types I through VI (lightest to darkest)
Examples and SPF guidance
Environmental factors that affect the amount of UV light exposure:
Sun elevation (avoid peak hours, 10:00-15:00)
Cloud coverage: more than 90% of UV light can penetrate clouds
Snow and ice - reflect UVB light
Ozone layer - absorbs UVC
What is SPF?
The ratio of the least amount of UVB energy required to produce a minimal erythema reaction) through sunscreen, compared to the amount of energy required to produce the same erythema without any sunscreen
Example - SPF 30 -> 30x longer exposure before sunburn vs without sunblock at all
How to optimize UV protection?
SPF of at least 15 to 30 daily, applied 15 to 30 mins BEFORE going outdoors
Reapply Q 2 hrs OR after water exposure
Avoid peak hours (1000-1500)
Wear dark, loose, dry clothing with a tight weave, wide-brimmed hat, long-sleeved shirt, pants
What is the best protection method against the sun? (Other than being inside)
Clothing
How does sunscreen work?
It scatters and reflects light
Titanium dioxide or zinc oxide
Absorbs radiation
Difference between waterproof and water-resistant sunscreen
Proof - good for 80 mins immersion
Resistant - good for 40 mins immersion
Which glass on the car protects against UV radiation better?
Windshield - side and rear are usually non-laminated
UVB is filtered but UVA is not
Advantages of sunscreen
Proven to reduce the risk of melanoma and non-melanoma skin CA
Reduces sxs of skin aging
Avoidance of sunburn
Disadvantages of sunscreen
Infants < 6 mo -> systemic absorption (due to lack of fully developed keratinization of epithelium)(use clothing instead)
Less Vitamin D production (easy to supplement)(you only need 20 mins/day of adequate sunshine for good Vit D production)
Definition of photoaging
Skin changes superimposed in intrinsic aging by chronic sun exposure
Sun induced damage includes:
Texture , vascular, pigmentation, and papular changes
What is solar elastosis?
Thickened, wrinkled, yellowish skin - forehead and back of neck
What is cutis rhomboidalis nuchae?
Sun-induced wrinkling on back of neck that forms a rhomboidal pattern
Features of eccymoses and stellate pseudoscars?
Bleeding into skin following minor trauma
Exposed surfaces of back of hands and arms
Atrophy, ease of skin tearing
What is venous lake?
Round, purple ectatic vessels
Lower lips and ears
Photoaging pigmentation changes are caused by:
Reactive hyperplasia of melanocytes
Freckles - small, oval, brown macules
Lentigo - large brown macules
What is poikiloderma of Civatte?
Red-brown reticulated pigmentation with telangiectasias, atrophy, prominent, prominent hair follicles
What are Favre Racouchot?
Comedomes and cysts around the eyes
Features of retinoids (topical)
Noninvasive but slow (3-6mos)
Increased photosensitivity during use
Treats fine wrinkles, pigmentation changes, tactile roughness (not effective or coarse wrinkling or telangiectasias)
Resurfacing txts include:
Chemical peels
Dermabrasion
“Lasers”
Faster results
Complications -> scarring, hypopigmentation
$$$
3 levels of resurfacing: superficial, medium, deep
Pellagra is typically related to:
Niacin deficiency