Urticaria Flashcards
What is it
- development of Itchy Hives
- Acute: <6wks
- Chronic: >6wks
What it look like
- Superficial wheals + Erythema (central + peripheral)
* due to leaky capillaries in papillary vascular plexus
History reveals
Acute swellings developing over a few mins (can occur anywhere)
Angioedema
- is when Edema involves:
- Dermis
- Subcutis (deep cutaneous Venous plexus)
- usually involves:
Eyes/Lips/Hands
Incidence of Urticaria
15-23%
Pathomechanism of urticaria
-leaky capillaries in the skin –> Cutaneous Edema
-Final step:
> Degranulation of Mast Cells –> release Inflmm mediators which cause the capillaries to be leaky
Etiology
Can follow:
- viral/parasite infxn
- drug rxn (aspirin/penicillin)
- Food Allergy
- SLE (rare)
- Autoimmune
Clinical Forms of Urticaria
1) Immunological Urticaria
2) Physical Urticaria
Immunological Urticaria
1) IgE Mediated:
- previously sensitized mast cells in skin
- acute
- AG = Food (nuts/milk/shellfish/eggs) / Drugs (penicillin)
2) Compliment Mediated
- compliment activation due to Immune complex formation
- acute
3) Autoimmune:
- common + Chronic
- Abs form against IgE a-subunit of Mast cells
4) Immunologic Contact:
- such as children with contact dermatitis -> sensitive to Environmental AG (Grass)
- Latex Rubber GLove
Physical Urticaria
1) FACTITIOUS URTICARIA:
- after stroking/scrathching
- itches and fades after 30mins
2) COLD URTICARIA:
- children/young adults
- ice-cube test
3) SOLAR URTICARIA:
- sunlight exposure
- wheezing + syncope
4) Cholinergic Urticaria:
- due to exersize to the point of sweating
5) AQUAGENIC URTICARIA:
6) Pressure Angioedema
- swelling due to sustained pressure (sttting)
- delay: 30-min-12hrs
Hereditory Angioedema
- Rare AD disorder
- Eruption due to: Physical/Emotional Trauma
- SERIOUS –> Mortality 15-30% due to Laryngeal Edema
