Urticaria (Hives)
Basics
Description
- Urticarial lesions are best described as raised, pruritic, circumscribed erythematous papules.
- Single lesions may coalesce as they enlarge, forming generalized, raised, erythematous areas.
- Transient, typically lasting several hours
- Also known as “hives” or “nettle rash”
- Acute: <6 weeks’ duration
- Chronic: >6 weeks’ duration
- Other similar but non-urticarial entities:
- Angioedema
- Urticarial-like lesions
- Form in the deep dermal, subcutaneous, and submucosal layers
- Anaphylaxis
- Hypersensitivity reaction after exposure to an antigen
- Producing respiratory compromise secondary to airway edema, urticarial rash, pruritus, and hypotension; can lead to shock
- Angioedema
Epidemiology
- Female-to-male ratio of 3:2
- No variation in race
Incidence
Lifetime incidence of 15–25%
General Prevention
When a trigger is identified, avoidance is the main preventive measure.
Pathophysiology
- Immune mediated
- Antigen is cross-linked to IgE on a mast cell.
- This event causes mast cell activation, leading to the release of vasoactive mediators, such as histamine, leukotrienes, prostaglandin D2, platelet-activating factor, and other vasoactive mediators.
- These vasoactive mediators cause pruritus, vasodilatation, and capillary leak, which lead to the characteristic findings.
- Common triggers include some medications such as penicillins, foods such as milk or eggs, and envenomations.
- Non–immune mediated
- Degranulation of mast cells secondary to other non-IgE reactions such as physical changes, chemicals, some medications such as β-lactams and sulfa-containing drugs, and some foods
- Autoimmune mediated
- Degranulation of mast cells caused by cross-linking of IgE by IgG or IgG binding to the high-affinity IgE (FcεRI) receptor on mast cells
Etiology
- Acute urticaria
- Viral infections are thought to make up approximately 80% of all cases of acute urticaria in children. Most commonly isolated causes include the following viruses:
- Picornavirus
- Coronavirus
- Epstein-Barr
- Hepatitis A, B, and C
- Parasitic infections
- Bacterial infections (especially group A strep)
- Medications: most frequently reported include the following:
- NSAIDs
- Opiates
- β-lactams
- Vancomycin
- Radiocontrast
- Foods
- Transfusion of blood products
- Food additives and dyes
- Natural remedies including cranberry, feverfew, glucosamine, and ginger
- Insect venom including bees, wasps, hornets
- Viral infections are thought to make up approximately 80% of all cases of acute urticaria in children. Most commonly isolated causes include the following viruses:
- Chronic urticaria
- Idiopathic: Most have an unknown cause, but many feel that an association with an autoimmune mechanism is likely.
- Physical (~20–30%)
- Dermatographism (9%): Stroking of skin using mild-to-moderate pressure with fingernail or hard object causes linear urticaria at site of contact.
- Cholinergic (5%): diffuse erythema and elevated but pale urticarial lesions; intense pruritus; associated with sweating reflex, so often associated with overheating or exertion; may be worsened in combination with other triggers in specific combinations
- Cold (3%): urticarial lesions present at areas of skin exposed to low temperatures; familial and nonhereditary forms
- Aquagenic: Urticarial lesions arise when the patient is exposed to water (e.g., bathtub, swimming pool).
- Delayed pressure/vibratory: Deep or prolonged pressure on skin produces significant urticaria and often angioedema. Vibratory urticaria is a form of delayed pressure urticaria caused by repetitive vibration (e.g., use of a jackhammer).
- Mast cell disease
- Urticaria pigmentosa: excessive number of mast cells in skin, bone marrow, lymph nodes, and other tissues; flares characterized by pruritus, flushing, tachycardia, nausea, and vomiting
- Systemic mastocytosis
- Systemic disease
- Rheumatologic
- Urticarial vasculitis: erythematous wheals that resemble urticaria but histologically appear as leukocytoclastic vasculitis; often presents with systemic symptoms and lasts >24 hours
- Cryopyrin-associated periodic syndromes can present with urticaria, such as Muckle-Wells syndrome: chronic recurrent urticaria, deafness, amyloidosis, and arthritis.
- Neoplasms
- Infections: parasites especially noted to cause chronic urticaria
- Autoimmune: antibodies to IgE or IgE receptor (FcεRI)
- Hashimoto disease, hypothyroidism
- Rheumatologic
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Citation
Cabana, Michael D., editor. "Urticaria (Hives)." 5-Minute Pediatric Consult, 8th ed., Wolters Kluwer, 2019. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/5-Minute-Pediatric-Consult/617061/all/Urticaria__Hives_.
Urticaria (Hives). In: Cabana MDM, ed. 5-Minute Pediatric Consult. Wolters Kluwer; 2019. https://peds.unboundmedicine.com/pedscentral/view/5-Minute-Pediatric-Consult/617061/all/Urticaria__Hives_. Accessed December 12, 2024.
Urticaria (Hives). (2019). In Cabana, M. D. (Ed.), 5-Minute Pediatric Consult (8th ed.). Wolters Kluwer. https://peds.unboundmedicine.com/pedscentral/view/5-Minute-Pediatric-Consult/617061/all/Urticaria__Hives_
Urticaria (Hives) [Internet]. In: Cabana MDM, editors. 5-Minute Pediatric Consult. Wolters Kluwer; 2019. [cited 2024 December 12]. Available from: https://peds.unboundmedicine.com/pedscentral/view/5-Minute-Pediatric-Consult/617061/all/Urticaria__Hives_.
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