Urticaria and Angioedema Flashcards
3 typical features of urticaria
- central swelling
- pruritus or burning sensation
- fleeting nature (returns to normal in 1-24 hrs)
what is angioedema
- sudden swelling of lower dermis and subcutis
- painiful > itchy
- sites: eyelids, mouth, genitals
- slower resolution
urticaria vs angioedema histology
urticaria: upper and middle dermis
angioedema: lower and subcutaneous tissue
pathophysio of urticaria and angioedema
mast cell degranulation
- histamine = itch neuronal pathway
- vasodilation, increased blood flow, pruritus = wheals
- neuropeptides = wheal and flare response
primary mediator of wheal and flare reaction
histamine
acute vs chronic urticaria
acute <6 wks
chronic >6 wks
t/f atopic individuals are at increased risk for acute urticaria, while non-atopic individuals are at risk for chronic urticaria
true
t/f progressive acute urticaria should be periodically reevaluated
true
most common cause of acute urticaria
transient viral infections
t/f empiric elimination diets are always recommended in acute urticaria
false
causes of acute urticaria
immunologic: ige and non-ige mediated
non-immunologic: radiocontrast, viral, opiates, nsaids
t/f etiologic agents in chronic urticaria are usually identifiable, while agents in acute are more diverse
false, baliktad
classification of urticaria subtypes
read
diagnosis of cold contact urticaria
suspect: rapid onset local pruritus and erythema after exposure to cold stimulus
dx: challenge testing with ice cube for 10-15 mins
(+) = reaction when rewarming chilled skin
manifestation of delayed pressure urticaria
- 4-6 hrs after pressure
- more angioedema
- perivascular mononuclear infiltrate
- sites of tight clothing
dx for delayed pressure urticaria
challenge testing by pressure applied perpendicular to skin
manifestation of solar urticaria
- 1-3 mins after sun exposure (pruritus –> edema)
- confined to sun exposed areas
rare inborn error of metabolism confused with solar urticaria
eryhtropoietic protoporphyria
dx of dermatographism
- can come with cholinergic or cold urticaria
- stroke skin with tongue depressor
cause: reflex vasoconstriction followed by pruritus, erythema, and linear wheal
pathogenesis of cholinergic urticaria
- associated with exercise, hot showers, sweating
- mediated by cholinergic nerve fibers on muscle and sweat glands
- elevated histamine triggered by changes of body temp
most common cause of chronic urticaria
idiopathic (but diagnosed by exclusion)
erythema multiforme
- ringed/target lesions
- persistent sx
- no prominent pruritus
urticarial vasculities
- palpable purpura/discoloration usually in lower extremities
- hives >24 hrs
- poor response to antihistamines
possible pe results
- linear wheals = dermographism
- small wheals with erythema = cholinergic urticaria
- wheals in exposed areas = solar/cold
- wheals on lower extremities = urticarial vasculitis
t/f acute and chronic urticaria always requires specific diagnostic tests
false, depends on history and pe
routine diagnostic tests for acute and chronic urticaria
acute: none
chronic: cbc, esr/crp, omission of drugs
diagnostic tests for subtypes of urticaria
read
principles of skin prick test
- site: volar surface of the forearm
- agents: positive control histamine, negative control saline or extract diluent
- immediate response is seen after 15-20 mins
- diameter more/= 3x3 mm is positive
t/f medications like antihistamine should be stopped one to several days prior to skin testing
true
diagnostic test for chronic urticaria
autologous skin test
- serum from patient is intradermally injected into skin
what is autoimmune urticaria
patients have anti-ige antibodies instead of anti-ige receptor antibodies (more severe)
first line treatment for urticaria
antihistamines/h1 receptor antagonists
- first gen for children
- can give 2nd gen, best routinely
indications for use of corticosteroids
- urticarial vasculitis
- delayed pressure urticaria
always use lowest effective dose!!
+ and - of cyclosporine
+: inhibits basophil histamine release (mast cell degranulation)
-: red swollen gums, abnormal hair growth
other medications for urticaria
- phototherapy: reduces mast cells for dermographism and chronic idiopathic urticaria
- omalizumab: chronic idiopathic, cholinergic, solar, cold
- leukotriene receptor antagonist
- h2 antagonists
step 1 of approach to chronic urticaria
monotherapy with 2nd gen antihistamine, avoid triggers
step 2 of approach to chronic urticaria
one or more of:
- dose adjustment of 2nd gen ah
- add another 2nd gen ah
- add h2 antagonist
- add leukotriene receptor antagonist
- add 1st gen ah @ bedtime
step 3 of approach to chronic urticaria
dose advancement of a potent antihistamine
step 4 of approach to chronic urticaria
add alternative:
- omalizumab or cyclosporine
- immunosuppressants, biologics
eaaci treatment algorithm for urticaria
- nsah -> 2 wks -> step up
- nsah updosing up to 4x -> 1-4 wks -> step up
- add leukotriene antagonist or change nsah -> 1-4 wks -> step up
- add cyclosporine a, h2-ah, dapsone, omalizumab
for exacerbations (step 3 and 4) use systemic steroid for 3-7 days
