Photodermatology

Question 1

What is cutaneous photosensitivity?

Answer 1

Photosensitivity relating to the skin

Question 2

What are the two forms of photosensitivity?

Answer 2

Phototoxicity

Photo-allergy

Question 3

What are Fitzpatrick sun-reactive photo-types?

Answer 3

A classification of skin into types based on how it reacts to sunlight
Types 1 to 6, 1 being very fair and 6 being very dark skin

Question 4

What are the steps of radiation being absorbed in the skin?

Answer 4

Sunlight hits the skin
Radiation is absorbed by chromophores in the dermis
Mediator release and inflammatory response
Damage is caused

Question 5

What area of skin is a good place to check cutaneous photosensitivity?

Answer 5

Retro-articular area (behind ears)

Question 6

What are chromophores?

Answer 6

Chemicals that absorb radiation

Question 7

What are the main groups of porphyria?

Answer 7

Phototoxic
Blistering and fragility
Acute attack
Congenital

Question 8

What are porphyria?

Answer 8

Photodermatology conditions triggered by sunlight

Question 9

What are common features of skin porphyria?

Answer 9

Skin blistering
Severe burning pain
Oral features

Question 10

What is the enzyme that causes porphyria cutanea tarda?

Answer 10

Uroporphyrinogen decarboxylase

Question 11

What is porphyria cutanea tarda?

Answer 11

The commonest one, acquired abnormality of uroporphyrinogen decarboxylase

Question 12

What are the causes of porphyria cutanea tarda?

Answer 12

Alcohol
Viral hepatitis
Oestrogens
Haemochromatosis

Question 13

What are the symptoms and signs of porphyria cutanea tarda?

Answer 13

Blisters
Erosions
Fragility and poor healing
Milia (small white structures, firm but not completely hard)
Hyperpigmentation
Hypertrichosis (increased hair growth)
Solar urticaria
Morphoea (area of inflammation and fibrosis)

Question 14

What investigation is done to diagnose porphyria cutanea tarda, and what does this involve?

Answer 14

Woods lamp

Skin or hair is examined while exposed to the black light emitted by a Woods lamp

Question 15

What investigation is used to screen for porphyria cutanea tarda?

Answer 15

Spectrometer

Question 16

What is the management for porphyria cutanea tarda?

Answer 16

Symptomatic relief

Treat the underlying disease

Question 17

What is the enzyme responsible for erythropoietic protoporphyria?

Answer 17

Ferro-chelatase

Question 18

What are the signs and symptoms fo erythropoietic protoporphyria?

Answer 18

Severe prickly burning pain on exposure to sunlight
Relieved by application of cold water
Subtle swelling or pinkness

Question 19

What are the investigations for erythropoietic protoporphyria?

Answer 19

Spectrofluorimetry
Quantitative RBC porphyrins for monitoring
Flourocytes
Transaminases
Hb

Question 20

What is the management for erythropoietic protoporphyria?

Answer 20

Light protection measures
6 monthly LFTs and RBC porphyrins
Avoid iron
Phototherapy
Antioxidants

Question 21

What light protection measures can be put into place for erythropoietic protoporphyria?

Answer 21

Behavioural - avoid sun
Clothing
Environmental - shade trees, window films
Sunscreen

Question 22

What is acute intermitted porphyria?

Answer 22

Porphyria that doesn’t affect skin