Ch 18 Skin Reactions to Light

Question 1

UVR wavelength

Answer 1

UVA-32-400
UVB-290-320
UVC-200-290

Question 2

UVA

Answer 2

• 320-400

- Not respnsible for sunburn, responsible for other light reaction and more likely to cause photoallergy, PCT

Question 3

UVB

Answer 3

• 290-320
• Cause of sunburn
• Cause of PMLR, LE

Question 4

UVC

Answer 4

-Causes skin cancer but most blocker by atmosphere

Question 5

Sunburn

Answer 5

• Chromophores absorb light lead to activation of IL-1 and TNF-a leading to inos.
• Resolves in days

Question 6

Photoxicity

Answer 6

• Occurs when a drug in the skin absorbs UV in a dose dependent way
• Not allergic
• Reaction is bullous and shows up immediately, photopatch testing not really useful
• Drugs: Griseofulvin, amiodarone, tetracyclines, ocp, thiazides, psoralens, sulphonamides

Question 7

Photoallergy

Answer 7

• Caused when sunlight leads to creation of an allergen
• Eczematous in appearance and takes days to develop
• Photopatch testing useful, most common with UVA

Question 8

Chronic Actinic Dermatitis

Answer 8

-Photoallergy that doesn’t go away

Question 9

Polymorphic Light Eruption (PMLR)

Answer 9

• Presenc of eczema after sun exposure
• Happens most commonly in early spring
• Thought the be due to exposure to self antigen after sun changes, often improves with tan, otherwise need light avoidance

Question 10

Solar Urticaria

Answer 10

• Urticaria
• Can be seen in PCT
• Tx with avoidance and beta carotene

Question 11

Aging

Answer 11

• Sun damage leads to loss of elastic fibers

- Batemens purpura