Porphyrias

Question 1

What are photodermatoses?

Answer 1

Skin disorders that are precipitated by exposure to sunlight.

Question 2

What is photosensitivity?

Answer 2

An abnormal cutaneous response to UV radiation with/out visible light.

Question 3

3 Types of Phototherapy

Answer 3

Broadband UVB, Narrow UVB, PUVA

Question 4

What is PUVA?

Answer 4

Photochemotherapy, UVA radiation combines with a chemical sensitiser, psoralen.

Question 5

Good clinical sign of photosensitivity

Answer 5

Sparing behind the ears.

Question 6

What are porphyrias?

Answer 6

A group of diseases in which substances called porphyrins build up affecting the skin or nervous system.

Question 7

Main groups of porphyrias

Answer 7

Phototoxic skin porphyrias
Blistering and skin porphyrias
Acute attack porphyrias
Severe congenital porphyrias

Question 8

When does it manifest cutaneously?

Answer 8

Where excess porphyrins accumulate in the skin.

Question 9

What are porphyrins?

Answer 9

Photoactive molecules and when exposed to light they cause local skin damage.

Question 10

What are the 2 cutaneous patterns of disease?

Answer 10

Immediate photosensitivity.

Vesiculo-erosive skin disease.

Question 11

What is immediate photosensitivity?

Answer 11

Usually 30mins after sun exposure. Severe burning pain, and discomfort in exposed areas. May have redness and swelling. But typically effects are not visible.

Question 12

What is vesicle-erosive skin disease?

Answer 12

Blistering (vesicles) and erosions - but only in sun exposed areas. Mild disease consists of skin fragility in exposed ares with a tendency to form blisters or erosions which heal slowly.

Question 13

Porphyria Cutanea Tarda is caused by

Answer 13

low levels of uroporphyrinogen decarboxylase.

Question 14

Symptoms of porphyria cutanea tarda

Answer 14

oncholysis
blistering in sun exposed areas
heal slowly and scar 
hyperpigmentation
hypertrichosis 
solar urticaria 
morphea

Question 15

What is morphea?

Answer 15

Localised scleroderma that involves isolated patches of hardened skin on face, hands, and feet, with no internal organ involvement.
Thickened skin, stiffeness, poor blood flow to fingers.

Question 16

Wine Red Coloured Urine

Answer 16

Porphyria Cutanea Tarda

Question 17

Diagnosing protophyria cutanea tarda?

Answer 17

Woods lamp - shine light on urine of someone with PCT it gives it colour.

Question 18

Management of PCT

Answer 18

Treat underlying cause, as it most likely due to liver disease.

Question 19

What is Erythropoietic Protophoryia?

Answer 19

Deficiency in ferrochelatase.

Manifests at puberty, but first presents in childhood.

Question 20

Symtoms of EP

Answer 20

Few minutes of exposure - pruritus, erythema, swelling, pain.

Question 21

Longer exposure to sun in EP

Answer 21

2nd degree burns

Question 22

Repeated sun exposure in EP

Answer 22

lichenification, hypperpigmentation, and scarring.

Question 23

Protoporphyrin accumulating to toxic levels leads to

Answer 23

Lier failure

Question 24

Investigations for EP

Answer 24

Quantitive RBC porphyrins 
fluorocytes
transaminases
red blood indices
photo testing
biliary tract USS.

Question 25

Treatment of EP

Answer 25

Genetic counselling
6 Monthly LFTS and RBC porphyrins
Visible light photo protection, measures
Phototherapy
Anti-oxidants (beta carotene, cysteine, high dose Vit C)
Avoid iron

Question 26

Acute intermittent porphyria differentials

Answer 26

Acute abdomen pain
Mono neuritis multiplex,
Guillain- Barre syndrome,
Psychoses

Question 27

What is acute intermittent porphyria

Answer 27

It is an autosomal dominant genetic metabolic disorder, doesn’t cause skin signs.

Question 28

High risk of what in AIP?

Answer 28

Hepatocellular carcinoma, 
Melanoma,
lymphoma,
Chronic hypertension, 
Chronic kidney disease, 
Chronic pain.

Question 29

Enzyme deficiency in AIP?

Answer 29

Porphobilinogen deaminase which results in acute neurotoxic reaction in many tissue.