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Dermatology > Porphyrias and photodermatology > Flashcards

Porphyrias and photodermatology Flashcards

1
Q

What is photobiology?

A

The study of non ionizing radiation on living systems

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2
Q

What is photdermatoses?

A

Skin conditions where UV radiation is the causitive agent

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3
Q

What are the different types of fitzpatrick sun-reactive skin phototypes?

A

Type 1 - will burn and never tan
Type 2 - will burn and sometimes tan
Type 3 - will usually tan
Type 4 - will never burn

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4
Q

What are some treatment options for photosensitivity?

A 
Behavioural avoidance
Clothing
Sunscreen use
Phototherapy
Chromophore removal
Inhibition of mediator 
Inhibition of inflammatory response
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5
Q

What are porphyrias?

A

Disorders resulting from low levels of enzymes responsible for the 5th step in heme production

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6
Q

What are the different types of porphyrias?

A

Erythropoietic protoporphyria
Blistering and fragility skin porphyrias
Acute attack porphyrias
Severe congenital prophyrias

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7
Q

What is porphyria cutanea tarda?

A

Combination of liver inflammation and liver iron overload that reduces the action of enzymes causing porphryia

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8
Q

What is the biochemical pathway for porphyria?

A

PCT is caused by partial inactivation of an enzyme called uroporphyrinogen decarboxylase (UROD) leading to a build up of porphyrins in the liver from which they overflow into the blood stream and thus reach the skin.
They concentrate in the DEJ causing blistering

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9
Q

What liver conditions can exacerbate PCT?

A

Excess alcohol consumption
Haemachromatosis
Viral infections of the liver such as hep C
Oestrogen therapy; combined pill or HRT

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10
Q

What are the symptoms of PCT?

A 
Blisters
Fragility 
Hyperpigmentation
Hypertrichosis
Solar uricaria
Morphoea
Dark urine
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11
Q

How is PCT diagnosed?

A

Levels of polyphyria in blood

Woods lamp - urine is flourscent

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12
Q

What are the aims of treatment in PCT?

A

Relieve the skin condition

Treat underlying disease to reduce risk of liver cirrhosis, hepatoma etc

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13
Q

What is is erythropoietic protoporphyria?

A

Build up of protoporphyrin in the red blood cells leading to a sensitivity to sunlight. This is due to a lack of ferrochelatase which usualyl converts protoporphyin into haem by adding iron

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14
Q

How does EPP lead to photosensitivity?

A

As blood passes through the skin, protoporphyrin absorbs the energy from sunlight and sets a chemical reaction damaging the skin
The nerve endings perieve this as itching or burning pain

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15
Q

What type of light is EPP sensitive to?

A

UVA and visible light

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16
Q

What are the symptoms of EPP?

A

Photosensitivity

17
Q

How is EPP diagnosed?

A 
Levels of porphyrins in blood
Transaminases
Hb for anaemia
Biliary tract USS 
Phototesting
18
Q

What systemic condition can EPP cause?

A

Gallstones

Liver failure

19
Q

How is EPP managed?

A 
6 monthly LFTs and RBC porphyrins
Visible light photoprotection 
Prophylactic TL-01 phototherapy
Anti-oxidants
Avoid iron
20
Q

What should be considered in a differential of AIP?

A

Acute abdomen
Monoeuritis multiplex
Guillain-barre
Psychoses

21
Q

Enzyme deficient in acute intermittent porpyria

A

Deficiency in PBG de-aminase

22
Q

Presentation of acute intermittent porpyria

A 
Severe abdo pain 
Constipation 
N+V 
Hyponatraemia 
Tachycardic 
Hypotensive 
NO SKIN PROBLEMS
23
Q

What type of UV radiation causes problems in porphyria?

A

UVA

24
Q

Enzyme deficiency in PCT

A

Uroporphyrinogen decarboxylase

25
Q

Presentation of PCT?

A

Blisters
Fragility
Hypertrichosis
Solar urticaria

26
Q

How is PCT diagnosed?

A

Coral pee

27
Q

What enzyme is deficient in erythropoietic protophyria?

A

Ferrochelatase

28
Q

Presentation of erythropoietic protoporphyria?

A 
Tingling
Itching
burning
Redness
Swelling after sun
Anaemia 
CHILDHOOD
29
Q

How are porphyrias treated?

A

Sun avoidance and visible light sun cream

Dermatology (24 decks)

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