Photodermatology Flashcards
Photobiology
The study of non-ionising radiation on living systems
Fitzpatrick sun-reactive skin phototypes
Type I - skin doesn’t tan, just burns
Type II - skin burns but can tan
Type III - skin can tan easily, especially after a few exposures but can still burn
Type IV - don’t burn often, often naturally tanned/dark skin
Type V - dark brown skin
Type VI - black skin
Which site involvement is a clue to cutaneous photosensitivity?
Retroauricular area
Main groups of porphyrias
Phototoxic skin porphyrias
Blistering and fragility skin porphyrias
Acute attack porphyrias
Severe congenital porphyrias
True or false - all the skin porphyrias involve porphyrins as chromophores
True
Chromophores
Chemicals that absorb radiation
Manifestations of porphyrias in the skin relate to what?
Where the porphyrins mainly accumulate
Common skin porphyria features
Blistering and fragility
Acute phototoxicity symptoms
Commonest porphyria
Porphyria cutanea tarda type I
What has reduced activity in porphyria cutanea tarda?
Uroporphyrinogen decarboxylase
Clinical presentation of porphyria cutanea tarda
Large blister (bullae) Erosion Photodistribution Milia (small white bumps that are firm but not hard) Hyperpigmentation Hypertrichosis Solar urticaria Morphoea Fragility
Investigations for porphyria cutanea tarda
Woods lamp (lamp that shines predominantly violet light) shine on urine
Aims of treatment in porphyria cutanea tarda
Relieve the skin disease and treat the underlying disease
Possible underlying causes of porphyria cutanea tarda
Alcohol
Viral hepatitis
Oestrogens
Haemochromatosis
What has a reduced activity in erythropoietic protoporphyria?
Ferrotelachase
