- Also called hives
- Etiology
- Basically anything, but often idiopathic
- Physical urticaria
- Most common
- Pressure
- Dermatographic urticaria
- Elevated/decreased body temperature
- Sweating
- Sun-exposure
- Allergic urticaria
- Foods
- Drugs
- Penicillin
- Aspirin
- ACE inhibitors
- NSAIDs
- Inhalants
- Autoimmune urticaria
- Vasculitic urticaria
- Infectious urticaria
- Others
- Insect bites/stings
- Pregnancy
- Exercise
- Additives to food, dermatological products, soaps, etc.
- Classification
- Acute < 6 weeks
- 95% of acute cases resolve
- 5% progress into chronic
- Chronic > 6 weeks
- 25% of all urticaria patient
- Etiology can’t be established in many cases
- Pathomechanism
- Local capillary vasodilation and transudation of fluid -> intradermal oedema
- Mostly due to histamine, bradykinin, complement factors
- Mast cell degranulation occurs
- In some cases, due to hypersensitivity type I
- Clinical features
- Pruritus
- Diffuse urtica/wheals
- Circumscribed, sharply demarcated
- Erythematous plaques, sometimes with central clearing
- Individual lesions disappear after 24 hours
- Angioedema may also occur
- Diagnosis
- Extensive history is essential
- Any new dermatological products, drugs, etc.
- Lab tests
- Inflammatory markers
- Autoantibodies
- Infections
- Prick test
- Patch test
- Treatment
- For chronic
- Oral antihistamines
- Cyclosporine
- Leukotriene antagonist
- Omalizumab (anti-IgE)