Photobiology and Photosensitive dermatoses

Question 1

What is included in optical radiation?

Answer 1

UV, visible light and infrared

Question 2

UV radiation exists at wavelengths above/below that of visible light

Answer 2

below

Question 3

What are the ranges of wavelengths for UVA, UVB, and UVC light?

Answer 3

UVA–> 320-400
UVB–> 280-320
UVC–> 200-280

Question 4

What UV radiation causes aging?

Answer 4

UVA

Question 5

What is minimal erythema dose (MED)

Answer 5

the minimal amount of a particular wavelength of light capable of causing redness of the skin

Question 6

The effect of absorption depends on the _______, the molecule that absorbs light energy in the skin

Answer 6

Chromophore

Question 7

a chromphore can absorb what kind of light rays?

Answer 7

UVA, UVB or both

Question 8

What effects does UV light have on DNA?

Answer 8

UVB suppresses DNA synthesis which mediates anti-inflammatory effects on the skin

Question 9

What effects does UV light have on melanin?

Answer 9

stimulates the melanocyte

Question 10

What effects does UV light have on protein?

Answer 10

collagen and elastic fiber degeneration—> results in photoaging

Question 11

What are often treated by laser therapies?

Answer 11

dyschromia and pigmented skin lesions
telangiectasias
vascular neoplasms

Question 12

lasers that target water are specifically used for what kind of pathology?

Answer 12

warts

Question 13

What is a Fitzpatrick skin type IV?

Answer 13

never burns always tans

Question 14

What is a Fitzpatrick skin type V

Answer 14

moderately pigmented skin

Question 15

What does Immediate tanning result from ?

Answer 15

UVA exposure from the oxidation of melanin

Question 16

What does Delayed tanning result from?

Answer 16

UVA and UVB exposure–> increased # of melanocytes, increased melanin synthesis and increased association of melanosomes with keratinocytes

Question 17

What are the pro-inflammatory properties of UV exposure?

Answer 17

sunburns, phototoxic and photoallergic reactions

Question 18

What are the anti-inflammatory properties of UV exposure?

Answer 18

used to treat dieases like psoriasis and atopic dermatitis

Question 19

Describe some common features of phototoxic reactions

Answer 19

Manifested by redness, swelling, and burning/stinging
sun-protected sites are spared
onset within 24 hours
NOT immune related so may occur upon first exposure

Question 20

What is Phytodermatisis?

Answer 20

occurs following exposure to caustic plant material coupled with UV light
plants may contain furocoumarins which is a photosensitizer

Question 21

What is the differences between phototoxic reactions and photoallergic?

Answer 21

Photoallergic has delayed onset because it is immune related
Photoallergic has redness and itching
Phototoxic has redness, swelling and burning/stinging

Question 22

What is a common causative agent of photoallergic reactions

Answer 22

sulfa drugs

Question 23

What is the clinical presentation of PMLE

Answer 23

itching, edema, pink, papules coalescing into plaques and vesicles of sun-exposed skin

Question 24

What is the treatment of PMLE?

Answer 24

avoid sun, topical corticosteroids, and possible phototherapy

Question 25

What are some common features of XP

Answer 25

autosomal recessive caused by impaired DNA nucleotides excision repair 30% risk to develop neurologic abnormalities

Question 26

What is the phototherapy recommendation for psoriasis?

Answer 26

narrow band UBV (311nm)

Question 27

What is psoralen?

Answer 27

medication that increases the absorption of UV light and the subsequent anti-inflammatory properties (most often used with UVA)

Question 28

what are examples of physical blockers of sunscreen?

Answer 28

zinc oxide and titanium dioxide

Question 29

What are UVA blockers?

Answer 29

Benxophenones Avobenzone Mexoryl Titanium dioxide/Zinc oxide

Question 30

What are UVB blockers?

Answer 30

``` PABA Padimate O Salicylates Cinnamates Titanium dioxide/ zinc oxide ```

Question 31

What is SPF?

Answer 31

The ratio of time development of minimal erythema dose compared to the onset of erythema in unprotected skin SOLELY DUE TO UVB EXPOSURE