Photodermatology Flashcards
What is cutaneous photosensitivity?
Photosensitivity relating to the skin
What are the two forms of photosensitivity?
Phototoxicity
Photo-allergy
What are Fitzpatrick sun-reactive photo-types?
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
What are the steps of radiation being absorbed in the skin?
Sunlight hits the skin
Radiation is absorbed by chromophores in the dermis
Mediator release and inflammatory response
Damage is caused
What area of skin is a good place to check cutaneous photosensitivity?
Retro-articular area (behind ears)
What are chromophores?
Chemicals that absorb radiation
What are the main groups of porphyria?
Phototoxic
Blistering and fragility
Acute attack
Congenital
What are porphyria?
Photodermatology conditions triggered by sunlight
What are common features of skin porphyria?
Skin blistering
Severe burning pain
Oral features
What is the enzyme that causes porphyria cutanea tarda?
Uroporphyrinogen decarboxylase
What is porphyria cutanea tarda?
The commonest one, acquired abnormality of uroporphyrinogen decarboxylase
What are the causes of porphyria cutanea tarda?
Alcohol
Viral hepatitis
Oestrogens
Haemochromatosis
What are the symptoms and signs of porphyria cutanea tarda?
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)
What investigation is done to diagnose porphyria cutanea tarda, and what does this involve?
Woods lamp
Skin or hair is examined while exposed to the black light emitted by a Woods lamp
What investigation is used to screen for porphyria cutanea tarda?
Spectrometer
What is the management for porphyria cutanea tarda?
Symptomatic relief
Treat the underlying disease
What is the enzyme responsible for erythropoietic protoporphyria?
Ferro-chelatase
What are the signs and symptoms fo erythropoietic protoporphyria?
Severe prickly burning pain on exposure to sunlight
Relieved by application of cold water
Subtle swelling or pinkness
What are the investigations for erythropoietic protoporphyria?
Spectrofluorimetry Quantitative RBC porphyrins for monitoring Flourocytes Transaminases Hb
What is the management for erythropoietic protoporphyria?
Light protection measures 6 monthly LFTs and RBC porphyrins Avoid iron Phototherapy Antioxidants
What light protection measures can be put into place for erythropoietic protoporphyria?
Behavioural - avoid sun
Clothing
Environmental - shade trees, window films
Sunscreen
What is acute intermitted porphyria?
Porphyria that doesn’t affect skin
