Urticaria Flashcards
Define urticaria
characterised by skin reaction to something
mast cell activation in dermis (urticaria) or deeper( angio-oedema)
Red, scratchy, swollen, blanching plaques
can also get angio-odema-swollen deeper soft tissue
acute-spontaneous of wheals and angiooedema for less than 6 weeks (resolves)
Chronic-more Than 6 weeks
can be chronic idiopathic (unclear aetiolgy) or inducible urticaria
Aetiology and risk factors urticaria
tons of things-but the ending cause is local mast cell activation in dermis (urticaria) or deeper( angio-oedema)
acute causes:
most common-allergy(food, medication, contact,)
Infections (Viruses, esp resp in children, bacteria-resp and G (strep, H.pylori), parasites-strongyloides)
AID, cancer,
physical-solar, pressure, heat, emotion, trauma, contact, exercise, vibratory
Chronic- chronic infect-EBV,CMV Foods-hidden allregens eaten without realising over and over Medication-unkown ingestion Latex-if long exposure can cause long urticaria systemic disease-acute or chronic Physical-same but more are idiopathic
Epidiemology of urticaria
Very common -food, medication, insects
contact, latex, etc
chronic-most commonly unkowingly eating something
Signs and Sx of urticaria
Make sure not anaphylaxis reaction
Hx-identify duration, full comprehensive Hx to find aetiology,
Skin-
Wheals-raised, very itchy skin (red at base, whiter at top)-lasting under 24h most of times
go white when you press on them (blanch)
they often disappear and reapear somewhere else
if they persist, or are painful/burn, don’t blanch-consider other diagnosis
Investigations of urticaria
Acute-need a good HX-thats where the biggest clue (like eating peanut before), or viral infection just before-
in general , if suspicious-skin prick test-with antigens that are suspected to be the cause
they have good negative value (if not swell-not fake), but 60% positive value-suggest the possibility of allergy
no other test
