Photodermatology Flashcards
What is photobiology?
The study of ionising radiation on living systems
Which subset of UV light causes sunburn?
UVB
What is the commonly used skin phototyping system used?
Fitzpatrick I-VI (classification
What are the treatment options for abnormal cutaneous sensitivity?
Behavioural avoidance (clothing, sunscreen, etc)
Phototherapy
PUVA
Pharmacotherapy
What are porphyrias?
Rare genetic conditions where substances called porphyrins accumulate causing various skin and/or neurological problems
What are the main groups of porphyrias?
Phototoxic skin porphyrias
Blistering/skin fragility porphyrias
Acute attack porphyrias
Severe congenital porphyrias
What are the main features of skin porphyrias?
Blistering
Skin fragility
Photosensitivity
Which enzyme is deficient in porphyria cutanea tarda?
Uroporphrinogen decarboxylase
In porphyria cutanea tarda the site of first involvement is usually the dorsal surfaces of the hands. T/F
True
How might porphyria cutanea tarda present?
Bulla & erosions Skin fragility Milia Hyperpigmentation Hypertrichosis Solar urticaria Morphea (hardened skin)
What are milia?
Keratin filled epidermal cysts
What are the investigations indicated for porphyria cutanea tarda?
Wood’s lamp (non-specific)
Spectrophotometer
What are the underlying causes of porphyria cutanea tarda?
Alcohol Viral hepatitis Oestrogens Haemochromatosis (i.e - chronic liver inflammation --> reduced activity of enzyme)
What enzyme is deficient in erythropoietic protoporphyria?
Ferrochelatase
Pain arising from erythropoietic protoporphyria cannot be controlled. T/F
True - once pain begins the only solution is to wait for it to pass
Does erythropoietic protoporphyria have a genetic component?
Yes. Mutations can be passed from parent to child or sporadic (often both must occur for disease to present)
How does erythropoietic protoporphyria present?
Slight swelling with erythema
Pain
What might give some relief to painful erythropoietic protoporphyria?
Applying cold
Circular scarring (similar to chicken pox scars) often occurs in erythropoietic protoprphyria. T/F
False - the scarring is more oval in shape (this gives it a distinction from chicken pox scarring)
What are the investigations for erythropoietic protoporphyria?
Plasma scanning with a spectrophotometer Quantative RBC porphyrins Fluorocytes Hb red cell indices Biliary tract USS (may cause pigment gallstones) Phototesting
What is the management of erythropoietic protoporphyria?
Photoprotective measures 6 monthly LFTs & RBC porphyrins Genetic counselling Prophylactic TL-01 phototherapy Antioxidants Avoidance of iron rich foodstuffs Treatment of liver problems
List some photoprotective measures
Behavioural
Clothing
Environmental
Topical sunscreen
What might be the differential for acute intermittent porphyria?
Acute abdomen
Mononeuritis multiplex
Guillian-Barre syndrome
Psychoses
What enzyme is deficient in acute intermittent porphyria?
PBG deaminase
