Urticaria and Angioedema Flashcards
What is urticaria (hives, weals)?
A transient (individual lesions last <24 hours) eruption of erythematous and edematous swellings of the dermis, usually associated with itching
Classification of urticaria?
- Acute - < 6 weeks duration
- Chronic - > 6 weeks duration
What is angio-oedema (angioneurotic oedema)?
Transient (24 to 48 hours at most) swellings in the deeper dermal, subcutaneous and submucosal
tissues
Why is knowing about urticaria important?
- Acute urticaria is very common
- varies between 1% to 30% of people affected in a lifetime, depending on which study you read - Chronic urticaria is not uncommon - prevalence about 1 in 1000, and often life quality-ruining
- Rarely, it is the presenting feature of an important underlying disease
e.g. certain helminthic
infections or systemic lupus erythematosus
Causes of urticaria?
- allergy
- direct chemical effects
- physical urticarias
- autoimmune
- associated with other diseases
- infections
- chronic spontaneous
Commonest cause of chronic urticaria?
chronic spontaneous
Allergy as the cause of urticaria?
specifically, IgE-mediated
Note: never the cause for chronic urticaria although people with chronic urticaria can also have allergy
Direct chemical effects causing urticaria?
- salicylates
- other drugs
Physical causes of urticaria?
- dermographism
- delayed pressure
- vibration
- aquagenic
- solar
- cold
- cholinergic
Autoimmune causes of urticaria?
- single system
- multisystem (e.g. SLE)
Urticaria associated with other diseases?
thyroid (lymphoma)
Infections that cause urticaria?
- bacterial dental infections
- candida – now controversial
- parasites - mainly helminths
e.g. ascariasis, anisakiasis,
strongyloidiasis
Chronic spontaneous causes of urticaria?
Exclude other causes, some cases may be autoimmune
- chronic urticaria may be
MULTIFACTORIAL
Causes of angioedema?
- allergy
- direct chemical effects
- physical urticarias
- autoimmune
- associated with other diseases
- infections
- chronic spontaneous
- C1 esterase inhibitor deficiency: inherited
- ACE inhibitors: acquired
Management of urticaria and angioedema?
- Take a medical history
- Examine
- Investigations if necessary (that is, rarely)
Treatments?
- If an underlying cause is identified treat the cause and if pseudo allergens or allergens are identified (on history) give avoidance advice
- If no identifiable underlying disease or relevant avoidable factors concentrate on suppression
Diagnoses where suppression is mainstay of treatment include?
- Acute urticaria (post-infective, triggered by initial pseudo allergen, etc)
- Chronic ordinary urticaria and angioedema
- synonyms include chronic non-allergic urticaria and chronic idiopathic urticaria
Suppressive treatments?
- Treatments that block the effect of
mediators released from mast cells,
including H1and H2– antagonist antihistamines, leukotriene antagonists, serotonin antagonists - Treatments that make mast cells less ready to degranulate, including ultraviolet phototherapies, ketotifen
