(Figure 3.21A, B) - Discrete pink areas of swelling involving either superficial skin or mucosa with associated pruritus; lesions last < 24 h, ± associated angioedema
- Acute urticaria < 6 weeks, chronic > 6 weeks
- Urticaria due to cross-linking of two or more high affinity IgE receptors (FcєRI) with subsequent release of mast cell storage granules:
- Newly formed mediators: prostaglandin D2, leukotriene C4/D4/E4, platelet-activating factor (PAF)
- Preformed: histamine, heparin, tryptase, chymase
- Causes: idiopathic, immunologic, non-immunologic
- Immunologic
- IgE-mediated type I hypersensitivity (allergic)
- Immune complex deposition (serum sickness)
- Complement-dependent
- Autoantibodies: anti-IgE or anti-FcєRI antibodies (most often seen in chronic urticaria)
- Non-immunologic (direct/indirect degranulation)
- Drugs (opiates, radiocontrast dye, polymyxin B, aspirin, NSAID), contact-induced (i.e. nettle stings), certain foods
- Histology: perivascular infiltrate of scant eosinophils and lymphocytes (sometimes neutrophils), ± eosinophils splayed between collagen bundles, ± dermal edema
- Treatment: remove trigger; antihistamine (H1), ± short course of oral corticosteroid; if chronic urticaria consider lab work (CBC, ESR, ANA, anti-IgE/FcєRI antibodies, anti-thyroid antibodies, stool ova/parasite)
| | | | | | | Type of Urticaria | | Description | | | Dermographism | | Urticarial lesions resulting from light scratching | | | Delayed pressure urticaria | | Deep swelling with overlying erythema at sites of sustained pressure occurring with a delay of up to 12 h | | | Cholinergic urticaria | | Small erythematous papules appearing within 15 min of sweat-inducing stimulus (i.e. physical exercise) | | | Solar urticaria | | Occurs typically within minutes of exposure to sun (UV or visible light), lasts for <1 h, may have accompanying headache and syncope | | | Aquagenic urticaria | | Eruption after contact with water, typically lasts for <1 h | | | Cold urticaria | | Urticaria in cold-exposed areas (often seen when skin rewarmed) | | | Contact urticaria | | Urticaria at site of contact (i.e., nettle stings, latex) |
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| | Figure 3.21
A: Urticaria
(Reprint from Misery L,
Stander S, eds. Pruritus.
London: Springer; 2010)
B: Dermographism |
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