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  Urticaria
  Hives
  Atopic dermatitis
  Dermographism Multimedia
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 Urticaria image

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Urticaria
Hives

Urticaria is a skin symptom that accompanies many allergic disorders . It is a relatively common disorder caused by localized mast-cell degranulation, with resultant dermal venular hyperpermeability culminating in pruritic wheals. Mostly results from an antigen-induced ( pollens , foods , drugs , insect venom ) release of histamine and other vasoactive amines via sensitization with specific IgE antibodies. Most individual lesions develop and fade within 24 hours.
Allergic skin diseases such as urticaria and angioedema as well as atopic dermatitis are not clearly defined as true allergic diseases. Urticaria and angioedema are both due to excessive mast cell activity in the skin. Chronic urticaria and angioedema are seldom due to a definable IgE mechanism (as is the case with all allergies) but, when determined, is generally due to a drug , food or food additive.

Classification of Urticaria
 Acute Urticaria and Urticaria with an Identifiable Cause
 Chronic Idiopathic Urticaria
 Physical Urticaria
 Aquagenic Urticaria
 Cholinergic Urticaria
 Cold-Induced Urticaria (cold urticaria)
  Dermographism (symptomatic dermographism)
 Delayed Pressure Urticaria
 Exercise-Induced Anaphylaxis
 Localized Heat Urticaria
 Solar Urticaria
 Vibratory Urticaria
 Angioedema
 Others
 Hereditary urticaria
 Contact urticaria
 Papular urticaria
 Urticarial vasculitis
 Urticaria pigmentosa


Atopic dermatitis is associated with high serum IgE levels as well as a history of atopic disease ( rhinitis , asthma , etc.). Unfortunately, management is difficult since the medications classically associated with treatment of allergic diseases (i.e. antihistamines ) have little effect in these patients.

Dermatographism
A common form of hives is dermatographism, which occurs in 5% of the population. The hives are caused by a constant stroking or rubbing of the skin and often occur following scratching, or when tight-fitting clothes rub the skin.


Common Causes of Urticaria :
 

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  http://www.hon.ch/Library/Theme/Allergy/Glossary/urticaria.html Last modified: Fri Jun 28 2002