Photodermatology

Question 1

define photodermatology

Answer 1

the study of the interaction between non-ionising radiation and the skin

Question 2

list some benefits of UV exposure

Answer 2

photosynthesis 
vit D synthesis 
heat
circadian rhythm 
bactericidal 
therapeutic and diagnostic uses 
vision

Question 3

list some hazards of UV exposure

Answer 3

sunburn 
eyes - conjunctivitis, keratitis, cataracts
photageing 
skin cancer
photosensitivity - photodermatoses

Question 4

What bands of UV radiation pass through the ozone layer, and what bands are completely absorbed by the ozone layer

Answer 4

UVC - all absorbed by the ozone layer
UVB - some absorbed by the ozone layer
UVA - a little absorbed by the ozone layer

Question 5

What UVR bands are we exposed to on earth

Answer 5

mainly UVA

some UVB

Question 6

What UVR band is most likely to cause sunburn - UVA or UVB and why

Answer 6

UVB - it is most active

Question 7

What band of UVR do sunbeds use

Answer 7

Fluorescent UVA

Question 8

What band of UVR is used in phototherapy

Answer 8

narrow band UVB

Question 9

In what conditions is UVA phototherapy used to treat

Answer 9

this is a new development for eczema, skin scleroderma

Question 10

What is photochemotherapy

Answer 10

aka PUVA = psoralen + UVA

Question 11

what is the role of psoralen

Answer 11

sensitises the skin to UVA

Question 12

What is used 1st line in therapeutic UVR: UVB phototherapy or photochemotherapy?

Answer 12

UVB phototherapy

Question 13

why is UVA Tx used second line to UVB phototherapy

Answer 13

with UVA there is an increased risk of skin cancer

Question 14

How many Fitzpatrick skin types are there

Answer 14

six

Question 15

Type I Fitzpatrick skin type

Answer 15

only burns

Question 16

Type II Fitzpatrick skin type

Answer 16

always burns, can tan

Question 17

Type III Fitzpatrick skin type

Answer 17

tans, can burn

Question 18

Type IV Fitzpatrick skin type

Answer 18

tans

Question 19

Type V Fitzpatrick skin type

Answer 19

dark brown skin

Question 20

Type VI Fitzpatrick skin type

Answer 20

black skin

Question 21

What happens to cells in the epidermis when someone is sunburned

Answer 21

apoptosis of keratinocytes

Question 22

Typical duration of onset of UVB “sunburn” erythema

Answer 22

2-4h, peak 12-24h

Question 23

Typical duration of onset of PUVA erythema

Answer 23

onset 24h, peak 96h

Question 24

Mediators of UVB erythema

Answer 24

prostaglandins

Question 25

Mediators of UVA erythema

Answer 25

oxygen

Question 26

effect of sunlight on the immune system

Answer 26

causes immunosuppression

Question 27

how does sunlight cause immunosuppression

Answer 27

langerhan's cell migrate from the BM to draining lymph nodes, and there is suppression of delayed hypersensitivity

Question 28

why is sunlight causing a suppression of delayed hypersensitivity particularly important?

Answer 28

important in the promotion of carcinogenesis

Question 29

what is photoageing also called?

Answer 29

solar elastosis

Question 30

list the 4 different categories of photodermatoses

Answer 30

1. Immunological/Idiopathic 2. Genetic 3. Chemical photosensitivity 4. Photoaggravated dermatoses

Question 31

List the different IMMUNOLOGICAL/IDIOPATHIC photodermatoses

Answer 31

- polymorphic light eruption - actinic prurigo - solar urticaria - chronic actinic dermatitis - hydroa vacciniforme

Question 32

what is a polymorphic light eruption (PLE)

Answer 32

after a few hours of sun exposure, papules and vesicles develop, which resolve after a few days without scarring

Question 33

what type of hypersensitivity reaction is PLE

Answer 33

Type IV

Question 34

Tx of PLE

Answer 34

watch and wait - will resolve UVB desensitisation (90% effective)

Question 35

Ix for PLE

Answer 35

UVA provocation test

Question 36

what is actinic prurigo

Answer 36

an idiopathic photodermatoses, that occurs in childhood (1st decade) with sore and red papules on the eyes, lips, end of nose that scars

Question 37

what antigen is associated with actinic prurigo

Answer 37

HLA DR4

Question 38

what is solar urticaria

Answer 38

an idiopathic photodermatoses that occurs within a few minutes of sun exposure.

Question 39

what type of hypersensitivity reaction is solar urticaria

Answer 39

type I

Question 40

Tx of solar urticaria

Answer 40

antihistamines | desensitisation

Question 41

what is chronic actinic dermatitis

Answer 41

an idiopathic photodermatoses that is essentially pho-exposed site eczema

Question 42

what type of hypersensitivity is chronic actinic dermatitis

Answer 42

type IV

Question 43

what bands of UVR is the person sensitive to in chronic actinic dermatitis

Answer 43

broadband - UVA, UVB and visible light

Question 44

who usually gets chronic actinic dermatitis

Answer 44

old men

Question 45

list the different GENETIC photodermatoses

Answer 45

xeroderma pigmentosum (the only one we need to know)

Question 46

what is xeroderma pigmentosum

Answer 46

autosomal recessive disease | - failure of DNA excision repair

Question 47

presentation of xeroderma pigmentosum

Answer 47

rapid photoageing of the skin and skin cancer | death in teen

Question 48

what type of skin cancer do people with xeroderma pigmentosum get

Answer 48

both melanoma and non-melanoma

Question 49

list the different CHEMICAL photodermatoses

Answer 49

exogenous - drugs | endogenous - porphyrias

Question 50

list the different drugs can induce photosensitivity

Answer 50

psoralens e.g. lime, celery antibiotics - sulphonamides - tetracyclines - fluroquinolones diuretics - thiazides - furosemide NSAIDS Quinine Amiodarone

Question 51

What is phytophotodermatosis

Answer 51

a condition in children where they have been exposed to psoralens, then exposed to UVA light

Question 52

What can phytophotodermatosis be confused with

Answer 52

Non-accidental injury

Question 53

What is a photoaggravated dermatoses

Answer 53

a pre-existing skin disease that is aggravated by sunlight

Question 54

List the different PHOTOAGGRAVATED dermatoses

Answer 54

``` eczema psoriasis rosacea pemphigus, pemphigoid erythema multiforme ```

Question 55

What are the mainstay investigations for photodermatoses

Answer 55

``` monochromator phototesting UVA provocation test MED test (minimal erythema dose test) patch tests HLA status histology ``` (Depends on individual presentation)