Photodermatology

Question 1

benefits of UV light

Answer 1

photosynthesis 
vit D synthesis 
heat 
vision 
circadian rhythms 
bactericidal 
therapeutic and diagnostic use

Question 2

hazards of sunlight exposure

Answer 2

sunburn 
- eyes
skin cancer 
photoageing 
photosensitivity

Question 3

types of UV light

Answer 3

UV A, B, C

Question 4

Ozone absorbs which UV ?

Answer 4

C and part of B

therefore we are exposed to UVA and some UVB

Question 5

UVC has the shortest wavelength, true or false

Answer 5

true

Question 6

which UV is more likely to produce sunburn

Answer 6

UVB

Question 7

sources of UV light

Answer 7

sun

artificial - therapeutic, sunbeds

Question 8

what light do sunbeds emit

Answer 8

fluorescent UVA and <1% UVB

Question 9

what types of light can be used in phototherapy

Answer 9

UVB - narrow band

UVA

Question 10

what is PUVA

Answer 10

photochemotherapy
Psoralen + UVA = PUVA
sensitise skin with psoralen and then irradiate skin with UVA
risk of skin cancer therefore UVB is trialled first and PUVA is last line

Question 11

how many types of Fitzpatrick skin type are there

Answer 11

1-6

Question 12

describe the Fitzpatrick skin types

Answer 12

1 - pale, always burns 
2 - burns but can tan 
3 - tans but can burn 
4 - tans 
5 - brown skin 
6 - black skin

Question 13

what actually happens in sunburn

Answer 13

keratinocyte apoptosis

Question 14

what causes sunburn and when is the onset and peak of symptoms

Answer 14

UVB
onset 2-4h
peak 12-24h

Question 15

onset and peak of PUVA erythema

Answer 15

onset 24h

peak 96h

Question 16

what causes UVB erythema

Answer 16

prostaglandins

Question 17

what causes UVA erythema

Answer 17

oxygen

Question 18

what are other consequences of sunburn

Answer 18

immunosuppression

• langerhans cell migration
• suppression of delayed hypersensitivity

Question 19

cumulative sun damage causes SCC/BCC?

Answer 19

SCC

Question 20

acute sunburns causes NMSC/MSC

Answer 20

melanoma skin cancer

Question 21

what is the mechanism of photoageing

Answer 21

solar elastosis

Question 22

what is the commonest caucasian skin cancer

Answer 22

BCC / rodent ulcer

Question 23

causes of photodermatoses

Answer 23

idiopathic 
genetic 
chemical photosensitivity
- exogenous 
- endogenous

Question 24

features of polymorphic light eruption PLE

Answer 24

very common 
young women
type 4 hypersensitivity 
few hours of sun exposure results in erythematous papules and vesicles on areas that are generally not exposed to the sun 
resolve over few days without scarring 
Mx - UVB desensitisation 'hardening'

Question 25

what test can provoke PLE if unsure of the diagnosis

Answer 25

UVA

Question 26

what is actinic prurigo

Answer 26

``` rare childhood onset F>M FH affects eyes, lips, end of nose resolution by adulthood ```

Question 27

what is solar urticaria

Answer 27

rare persistent, immediate and severe onset abnormally sensitive to UVA and visible wavelengths type 1 hypersensitivity

Question 28

what is chronic actinic dermatitis

Answer 28

``` common Males over 50 photoexposed site eczema broadband photosensitivity background atopic eczema and CAD e.g. plants Type 4 hypersensitivity ```

Question 29

example of genetic photodermatoses

Answer 29

xeroderma pigmentosum

Question 30

what is xeroderma pigmentosum

Answer 30

``` AR inheritance failure of DNA excision repair mechanisms rapid photoageing of skin development of skin cancers in childhood death in teens ```

Question 31

causes of drug induced photosensitivity

Answer 31

``` psoralens - lime, celery, parsley antibiotics - sulphonamides, tetracyclines, fluoroquinolones diuretics - thiazides, furosemide NSAIDs quinine amiodarone ```

Question 32

what UV light mediates drug induced photosensitivity

Answer 32

UVA

Question 33

example of endogenous chemical photosensitivity

Answer 33

porphyrias

Question 34

example of an inherited porphyria

Answer 34

erythropoeitic protoporphyria EPP

Question 35

examples of acquired porphyria

Answer 35

porphyria cutanea tarda PCT

Question 36

causes of PCT

Answer 36

haemochromatosis viral hepatitis increased oestrogen alcohol

Question 37

what are photoaggravated dermatoses | give examples

Answer 37

skin disease which is aggravated but not caused by sunlight | eczema, psoriasis, SLE, rosacea, pemphigoid, pemphigus, EM

Question 38

mainstay investigations for photodermatoses

Answer 38

``` monochromator phototesting provocation test MED test photopatch tests porphyrins, lupus studies HLA histology ```

Question 39

management options

Answer 39

phototherapy PUVA laser PDT

Question 40

what is photodermatology

Answer 40

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

Question 41

types of sunscreen

Answer 41

reflectant - very thick | chemical - absorb