Photodermatology and porphyrias Flashcards
what is cutaneous photo sensitivity
an abnormal cutaneous to UV radiation or visible light
what can cause cutaneous photo-sensitivity
idiopathic
genophotodermatoses (inherited)
porphyrias (disorders that result from a buildup of natural chemicals that produce porphyrin in your body)
drug induced
what are the treatment options for cutaneous photosensitivities
behavioural avoidance
clothing
sunscreen use
hardening (phototherapy, PUVA)
chromophore (absorbs sunlight) removal
inhibition of mediator release/action or inflammatory response
what causes the biochemistry of all porphyrias
lack of activity of an enzyme
what are the main types of porphyrias
phototoxic (erythropoietic protoporphyria)
blistering and fragile skin
acute attack (some have no skin involvement)
severe congenital
what causes porphyria cutanea tarda
liver inflammation and liver iron overload decreases uroporphyinogen decarboxylase activity
what is the typical presentation of porphyria cutanea tarda
blisters fragility hyperpigmentation, hypertrichosis, solar uticaria, morphoea
what investigations can be done into porphyria cutanea tarda
woods lamp- makes uroporphrtines in urine (as water soluble) glow red flurorescent
what can cause porphyria cutanea tarda
alcohol, viral hepatitis, haemochromatosis
lack of what enzyme causes Erythropoietic protoporphyria
ferrochelatase
what else is associated with Erythropoietic protoporphyria
mild anaemia, gall stones, liver failure
how does Erythropoietic protoporphyria
present
not much to see, light redness
what is the cure for Erythropoietic protoporphyria
no cure apart from bone marrow transplant
what is enzyme
deficiency causes acute intermittent porphyria
porphobilinogen deaminase
how does acute intermittent porphyria present
no skin manifestations but display neurovisceral signs and symptoms, including autonomic neuropathies that produce constipation, abdominal pain, vomiting, or hypertension and tachycardia
