Photosensitive Skin Diseases

Question 1

What is sunburn?

Answer 1

Erythema and vasodilation of skin causes by excessive UV radiation 2-6 hours post-exposure

Question 2

Sunburn symptoms

Answer 2

Erythematous
Tender
Hot to touch
Blistering
Severe = blistering, dehydration, infection, electrolyte imbalance, shock
Followed by desquamation and pigmentation

Question 3

Describe polymorphic light eruption

Answer 3

Prickly heat
Itchy erythematous eruption
Spares habitually exposed areas (face, hands)
?autoimmune inflammatory response of skin to UV radiation

Question 4

Polymorphic light eruption (PLE) treatment

Answer 4

Sun avoidance/sunblock
Severe = topical/oral steroids
Prophylactic UVB/PUVA

Question 5

What does spf on sun cream refer to?

Answer 5

UVB protection
(Sun protection factor)

Question 6

What do stars on sun cream refer to?

Answer 6

UVA protection

Question 7

Describe chronic actinic dermatitis

Answer 7

Men >50 years
Itchy, erythematous, thickened xeroderma
Sun-exposed skin

Question 8

Chronic actinic dermatitis treatment

Answer 8

Sun avoidance/sunblock
Emollients, topical steroids

Question 9

What is solar urticaria?

Answer 9

Urticaria within minutes of UV light
Lasts several hours
Raised erythematous weals

Question 10

What is actinic prurigo?

Answer 10

Photosensitivity causing very itchy papules on sun-exposed areas
Normally manifests children <10
More common in darker skin types
Often lips and face

Question 11

Actinic prurigo treatment

Answer 11

Emollients
Topical steroids
Hydroxychloroquine
Desensitisation

Question 12

What is Hydroa Vacciniforme?

Answer 12

Blisters over sun-exposed areas
Heal with scarring
30-120 mins after exposure
Burning sensation/itching
Resolves once teenager but left with scarring

Question 13

What is xeroderma pigmentosum?

Answer 13

Rare autosomal recessive defect in DNA repair results in photosensitivity’, skin ageing, tendency to skin cancers
Can be associated with neurological or ocular disease

Question 14

Xeroderma pigmentosum management

Answer 14

Sun avoidance/protection
Regular skin examinations

Question 15

What causes cutaneous porphyrias?

Answer 15

Defective enzyme in haem synthesis (mainly in liver and bone marrow)

Question 16

Porphyria Cutanea Tarda (PCT) presentation

Answer 16

Erythema
Blisters
Erosions
Hypertrichosis
In response to UV radiation or minor trauma
Often on hands, face, neck and chest

Question 17

Porphyria Cutanea Tarda causes

Answer 17

Inherited (autosomal dominant or sporadic)
Alcohol
Oestrogen
Iron overload
Pesticides

Question 18

Porphyria Cutanea Tarda investigation

Answer 18

Biopsy
Urinary porphyrins
Woods light (fluoresces coral pink)

Question 19

Porphyria Cutanea Tarda treatment

Answer 19

Avoid alcohol, oestrogens, iron
Sunblock/avoidance
Venesection if necessary
Rarely hydroxychloroquine

Question 20

Cutaneous lupus erythematosus presentation

Answer 20

Malar (butterfly) rash
Photosensitivity
Mouth ulcers
Urticaria
Hair thinning

Question 21

Which drugs can induce lupus?

Answer 21

Hydralazine
Carbamazepine
Lithium
Phenytoin
Sulphonamides
Minocycline

Question 22

What is a phototoxic reaction? (Drug induced photosensitivity)

Answer 22

Exaggerated sunburn reaction
Minutes/hours after exposure
Photopatch negative

Question 23

What is a photo allergic reaction? (Drug induced photosensitivity)

Answer 23

Eczematous type reaction
May spread to non-exposed areas
Hyperpigmentation does not occur
Photo patch positive

Question 24

What causes phytophoyodermatitis and what does it look like?

Answer 24

Organic psoralens found in lime, celery, carrot, hog weed etc
Rash appears after subsequent UV exposure
Irregular erythema and blistering

Question 25

Which diseases can UV worsen?

Answer 25

Darier’s
HSV
Pellagra
Photoaggravated psoriasis

Question 26

Which diseases can UV improve?

Answer 26

Atopic eczema
CTCL
Pityriasis lichenoides
Pityriasis rosea
Psoriasis
Pruritis of renal failure and liver disease