Urticaria Flashcards
What are two other terms used for ‘urticaria’?
1) hives
2) wheels
What is urticaria?
Swelling involving the superficial dermis, raising the epidermis
What is angioedema?
the result of increased vascular permeability that can lead to swelling of the face, tongue, and airway
Summarise the pathophysiology of urticaria:
mast cells release histamine and other pro-inflammatory chemicals which stimulate an inflammatory response
What time frame is used to define acute urticaria?
less than 6 weeks
What time frame is used to define chronic urticaria?
symptoms nearly on a daily basis for 6 weeks
Give 6 causes of acute urticaria:
1) allergies to food, medications or animals
2) contact with chemicals, latex or stinging nettles
3) medications
4) viral infections
5) insect bites
6) dermatographism
What is dermatographism?
rubbing of the skin
Describe the clinical presentation seen in urticaria:
highly pruritic raised skin rash with lesions that may be ring shaped with central raised swelling surrounded by an area of erythema
What is meant when acute urticaria is described as ‘fleeting’?
the raised skin often appears and disappears quickly
What is chronic urticaria?
an autoimmune condition where autoantibodies target mast cells and trigger them to release histamines
What is chronic idiopathic urticaria?
recurrent episodes of chronic urticaria without a clear underlying cause or trigger
What are the 3 types of chronic urticaria?
1) chronic idiopathic urticaria
2) autoimmune urticaria
3) chronic inducible urticaria
Give 6 triggers of chronic inducible urticaria:
1) sunlight
2) temperature change
3) exercise
4) strong emotions
5) hot/ cold weather
6) pressure (dermatographism)
What are pruritic wheels?
Recurrent transient erythematous and oedematous lesions that last less than 24 hrs
How often does angio-oedema occur in urticaria?
40% of urticaria cases
What is physical urticaria caused by?
- Dermographism
- Cold contact
- Delayed pressure
- Solar urticaria
What is urticarial vasculitis?
Cutaneous lesions that resemble urticaria and small-vessel cutaneous vasculitis (Palpable purpura)
If low complement levels, it may be associated with SLE
What type of hypersensitivity reaction is urticaria?
Type 1
What are the risk factors for urticaria?
- Positive family history
- Exposure to drug/food trigger
- Recent viral infection/insect bite
- Female sex
What is found upon history and examination of a patient with urticaria?
- Urticaria lesions (wheals) are reddish or white transient papules or plaques representing dermal oedema
- lesions are widespread and last a few hours
- Lesions may become confluent and form circular or sinusoidal patterns
What are the key diagnostic factors of urticaria?
- Erythematous oedematous lesions
- Pruritus
- Resolutions within 24 hrs
- Swelling of tongue, face and lip
- Blanching lesions
- Stridor (uncommon)
What are 5 differential diagnoses for Urticaria?
- Dermographism
- Atopic dermatitis
- Contact dermatitis
- Urticarial vasculitis
- Papular urticaria (insect bites)
How is urticaria diagnosed?
By clinical impression
What investigations can be used for ordinary urticaria?
Acute: Skin prick or blood RAST tests
Chronic - 30% have histamine releasing antibodies
What is the mainstay treatment of both acute and chronic urticarnia?
Antihistamines
What treatment can be used for urticarial vasculitis?
Antihistamines
NSAIDs
- maybe immunosuppressive therapy
What is the management of urticaria with anaphylaxis?
- Adrenaline IM
- Airway management/ oxygen
- Antihistamines (Chlorphenamine)
- IV fluids
- Systemic corticosteroids ( IV hydrocortisone)
What is the management of urticaria without anaphylaxis?
- Identify and stop offending stimulus
- Antihistamines ( sedating= chlorophenamine, hydroxyine non-sedating= cetrizine, fexofenadine)
- Systemic corticosteroids for severe acute urticaria and angioedema (Prednisolone)
- Anti-pruritic emollients
What drug class is first line to treat urticaria?
oral second generation (non-sedating) antihistamines
Give 4 examples of oral second generation (non-sedating) antihistamines:
1) fexofenadine
2) cetirizine
3) levocetirizine
4) desloratadine
Give 3 specialist treatments for urticaria:
1) anti-leukotrienes
2) omalizumab
3) cyclosporin
Give an example of an anti-leukotriene drug:
montelukast
What is the mechanism of omalizumab in treating allergies and urticaria?
it targets IgE
Case History 1:
A 50-year-old man with a past medical history of HTN and a recent diagnosis of osteoarthritis presents to his primary care physician with complaints of hives over the past 2 weeks. He reports red and raised lesions that are intensely pruritic and involve his torso and bilateral extremities. He denies any swelling or painassociated with the episodes. The patient also denies any unusual food ingestions or recent changes in his environment (e.g., soaps, detergents). However, he has recently started using scheduled ibuprofen for osteoarthritis
Case history 2:
A 33-year-old woman with a past medical history of hypothyroidism presents with complaints of hives for the past 4 months. She describes red, raised, itchy lesions that involve her entire body, including her face. She also reports 2 episodes of face and tongue swelling, each of which prompted her to report to the nearest emergency department. In addition to itching, the lesions sometimes cause a burning sensation. The lesions and symptoms resolve over 24 to 36 hours. Despite countless attempts, she has not been able to associate the hives with any specific triggers. The patient voices extreme frustration and feelings of depression, which she attributes to her recent condition
Other presentations:
Rarely, a patient presents with angio-oedema in the absence of any associated urticaria. This unusual pattern should prompt additional evaluation for hereditary angio-oedema, acquired angio-oedema, or drug-related angio-oedema (e.g., ACE inhibitor related). For patients with urticaria, unusual features can include pain/burning rather than pruritus, lesions that last longer than 24 hours, or lesions that leave residual bruising or discoloration upon resolution.These features should raise the possibility of a different diagnosis, such as urticarial vasculitis.
