Photodermatology

Question 1

What is photobiology?

Answer 1

The study of ionising radiation on living systems

Question 2

Which subset of UV light causes sunburn?

Answer 2

UVB

Question 3

What is the commonly used skin phototyping system used?

Answer 3

Fitzpatrick I-VI (classification

Question 4

What are the treatment options for abnormal cutaneous sensitivity?

Answer 4

Behavioural avoidance (clothing, sunscreen, etc)
Phototherapy
PUVA
Pharmacotherapy

Question 5

What are porphyrias?

Answer 5

Rare genetic conditions where substances called porphyrins accumulate causing various skin and/or neurological problems

Question 6

What are the main groups of porphyrias?

Answer 6

Phototoxic skin porphyrias
Blistering/skin fragility porphyrias
Acute attack porphyrias
Severe congenital porphyrias

Question 7

What are the main features of skin porphyrias?

Answer 7

Blistering
Skin fragility
Photosensitivity

Question 8

Which enzyme is deficient in porphyria cutanea tarda?

Answer 8

Uroporphrinogen decarboxylase

Question 9

In porphyria cutanea tarda the site of first involvement is usually the dorsal surfaces of the hands. T/F

Answer 9

True

Question 10

How might porphyria cutanea tarda present?

Answer 10

Bulla & erosions
Skin fragility
Milia 
Hyperpigmentation
Hypertrichosis 
Solar urticaria 
Morphea (hardened skin)

Question 11

What are milia?

Answer 11

Keratin filled epidermal cysts

Question 12

What are the investigations indicated for porphyria cutanea tarda?

Answer 12

Wood’s lamp (non-specific)

Spectrophotometer

Question 13

What are the underlying causes of porphyria cutanea tarda?

Answer 13

Alcohol
Viral hepatitis
Oestrogens
Haemochromatosis
(i.e - chronic liver inflammation --> reduced activity of enzyme)

Question 14

What enzyme is deficient in erythropoietic protoporphyria?

Answer 14

Ferrochelatase

Question 15

Pain arising from erythropoietic protoporphyria cannot be controlled. T/F

Answer 15

True - once pain begins the only solution is to wait for it to pass

Question 16

Does erythropoietic protoporphyria have a genetic component?

Answer 16

Yes. Mutations can be passed from parent to child or sporadic (often both must occur for disease to present)

Question 17

How does erythropoietic protoporphyria present?

Answer 17

Slight swelling with erythema

Pain

Question 18

What might give some relief to painful erythropoietic protoporphyria?

Answer 18

Applying cold

Question 19

Circular scarring (similar to chicken pox scars) often occurs in erythropoietic protoprphyria. T/F

Answer 19

False - the scarring is more oval in shape (this gives it a distinction from chicken pox scarring)

Question 20

What are the investigations for erythropoietic protoporphyria?

Answer 20

Plasma scanning with a spectrophotometer
Quantative RBC porphyrins
Fluorocytes
Hb red cell indices
Biliary tract USS (may cause pigment gallstones)
Phototesting

Question 21

What is the management of erythropoietic protoporphyria?

Answer 21

Photoprotective measures
6 monthly LFTs & RBC porphyrins
Genetic counselling 
Prophylactic TL-01 phototherapy
Antioxidants
Avoidance of iron rich foodstuffs
Treatment of liver problems

Question 22

List some photoprotective measures

Answer 22

Behavioural
Clothing
Environmental
Topical sunscreen

Question 23

What might be the differential for acute intermittent porphyria?

Answer 23

Acute abdomen
Mononeuritis multiplex
Guillian-Barre syndrome
Psychoses

Question 24

What enzyme is deficient in acute intermittent porphyria?

Answer 24

PBG deaminase