Porphyrias

Question 1

What is meant by cutaneous photosensitivity?

Answer 1

Abnormal skin reaction to UV, and sometimes visible, light

Question 2

What is porphyria?

Answer 2

Hereditary disease where there is build up of porphyrins, caused by reduced enzyme activity in the haem pathway
These react with light to produce skin reactions

Question 3

Name the 3 most common porphyrias

Answer 3

Porphoryia cutanea tarda
Erythropoietic protoporphyria
Variegate porphyria

Question 4

How does porphyria cutanea tarda arise?

Answer 4

Reduced activity of uroporphyrinogen decarboxylase causes build up of uroporphyrins that react with light (not UV)

Question 5

List symptoms of porphyria cutanea tarda

Answer 5

Blistering
Skin fragility
Hyperpigmentation
Hypertrichosis

Question 6

List 4 causes of porphyria cutanea tarda

Answer 6

Alcohol
Viral hepatitis
High oestrogen
Haemachromatosis

Question 7

How does erythropoietic protoporphyria arise?

Answer 7

Reduced activity of ferrochelatase causes build up of protoporphyrins

Question 8

List symptoms of erythropoietic protoporphyria

Answer 8

Swelling/burning
Itching
Pain

Question 9

How does acute intermittent porphyria arise?

Answer 9

Reduced activity of PBG deaminase causes build up of uroporphyrins (Doesn’t usually effect the skin)

Question 10

Investigations for PCT?

Answer 10

Woods lamp

Measure the amount of porphyria persecutors/porphyrins in the blood

Question 11

What is the management for PCT

Answer 11

Sun avoidence (e.g. window film for car or home)
Desensitisation to harden skin
Topical steroids if rash

Question 12

What is the management for erythropoietic protoporphyria?

Answer 12

Monitor LFTs/RBC and stay away from visible light

Question 13

Porphyria cutanea tarda can be genetic or sporadic (acquired). True/false?

Answer 13

True