Overview
Definition:
Urticaria, commonly known as hives, is a vascular reaction in the upper dermis characterized by transient, pruritic, erythematous, and edematous wheals
It is often accompanied by angioedema, which involves deeper dermal and subcutaneous tissue swelling.
Epidemiology:
Urticaria is a common condition in childhood, with estimates suggesting that up to 15-20% of children experience at least one episode
Acute urticaria is more prevalent than chronic urticaria in pediatric populations
Chronic urticaria (CU) is defined as daily or near-daily urticaria for at least six weeks.
Clinical Significance:
Urticaria can range from a mild, self-limiting condition to a significant health issue impacting quality of life due to intense pruritus and discomfort
In pediatric practice, differentiating acute from chronic urticaria is crucial for appropriate diagnosis and management, and identifying underlying causes is important, especially in persistent cases.
Clinical Presentation
Symptoms:
Characterized by sudden onset of intensely itchy, raised, pink or red, transient lesions (wheals) that vary in size and shape
Wheals typically appear and disappear within minutes to hours at different sites
Angioedema may occur simultaneously, presenting as deeper swelling of lips, eyelids, tongue, face, or extremities, usually without significant pruritus but can cause tightness or pain.
Signs:
Visible, raised, edematous, erythematous, and blanching lesions (wheals) on the skin, often with surrounding pallor
Lesions are typically well-demarcated and may coalesce
Angioedema presents as non-pitting edema of subcutaneous tissues.
Diagnostic Criteria:
Diagnosis of urticaria is primarily clinical
International guidelines define acute urticaria as lasting less than 6 weeks, while chronic urticaria persists for 6 weeks or longer
Chronic spontaneous urticaria (CSU) is diagnosed when no identifiable external trigger can be found, and it is characterized by recurrent wheals and/or angioedema.
Diagnostic Approach
History Taking:
Detailed history is paramount
Inquire about the duration of lesions, pattern of recurrence, associated symptoms (fever, arthralgia, gastrointestinal upset), potential triggers (foods, medications, infections, insect bites, physical factors like heat, cold, pressure, vibration, sunlight), family history of atopy or urticaria
For acute urticaria, focus on recent exposures
for chronic, explore systemic symptoms and autoimmune markers.
Physical Examination:
Thorough skin examination to assess the type, distribution, and morphology of lesions
Look for wheals, angioedema, and any signs of underlying infection or systemic disease
Examine oral mucosa, pharynx, and extremities for angioedema
Palpate for lymphadenopathy or signs of vasculitis.
Investigations:
Routine laboratory investigations are usually not required for acute urticaria
For chronic urticaria, consider complete blood count (CBC) with differential, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), liver function tests, and thyroid function tests (TSH, free T4)
Autoimmune workup may include antinuclear antibodies (ANA), anti-thyroid peroxidase antibodies (anti-TPO), and anti-thyroglobulin antibodies
Allergy testing (skin prick tests or specific IgE) might be indicated if a specific allergen is suspected for acute urticaria, but is less useful for CSU.
Differential Diagnosis:
Differential diagnosis for urticaria includes urticarial vasculitis (lesions last >24 hours, may be painful or burning, can leave purpura), insect bite reactions (localized swelling with a central bite mark), erythema multiforme (target lesions), viral exanthems, drug eruptions, mastocytosis (urticaria pigmentosa), and hereditary angioedema.
Management
Initial Management:
For acute urticaria, prompt identification and avoidance of triggers is the first step
If the cause is identifiable (e.g., food), strict avoidance is recommended
For severe cases with airway compromise, immediate airway management and administration of epinephrine are essential.
Medical Management:
First-line treatment for both acute and chronic urticaria is with second-generation H1 antihistamines (e.g., Cetirizine 5-10 mg once daily, Levocetirizine 5 mg once daily, Loratadine 10 mg once daily, Fexofenadine 30-60 mg twice daily)
Doses can be increased up to four times the standard dose for refractory cases
For chronic urticaria, if antihistamines are insufficient, consider adding a short course of oral corticosteroids (e.g., Prednisolone 0.5-1 mg/kg/day for 3-5 days) for severe exacerbations
Omalizumab is a highly effective option for chronic spontaneous urticaria refractory to antihistamines, administered subcutaneously every 4 weeks.
Surgical Management:
Surgical intervention is generally not indicated for urticaria itself
However, in rare cases of severe, recurrent angioedema with risk of airway compromise, tracheostomy might be considered as a life-saving measure, though this is exceptionally rare.
Supportive Care:
Cool compresses, soothing lotions, and distraction techniques can help alleviate pruritus
Patient education regarding triggers, treatment, and when to seek medical attention is crucial
Monitoring for signs of infection or systemic involvement is important, especially in chronic cases.
Complications
Early Complications:
Anaphylaxis, angioedema leading to upper airway obstruction and respiratory distress
Severe pruritus can lead to sleep disturbance and impaired quality of life.
Late Complications:
Chronic urticaria can lead to significant psychological distress, including anxiety and depression
Persistent inflammation can rarely be associated with underlying autoimmune conditions or malignancies, though this is more common in older adults.
Prevention Strategies:
Primary prevention involves identifying and avoiding known allergens or triggers
For individuals with a history of severe reactions, maintaining an emergency kit with epinephrine is crucial
In chronic urticaria, consistent use of maintenance therapy with antihistamines can prevent exacerbations.
Prognosis
Factors Affecting Prognosis:
Acute urticaria generally has a good prognosis, resolving within days to weeks
Chronic urticaria can be persistent and challenging to manage, with a significant proportion of patients experiencing symptoms for years
Factors influencing prognosis include the underlying cause, response to treatment, and presence of comorbidities.
Outcomes:
Most cases of acute urticaria resolve completely
Chronic urticaria often requires long-term management, with a subset of patients achieving remission spontaneously over time
Omalizumab has shown high rates of remission and symptom control in refractory CSU.
Follow Up:
Regular follow-up appointments are necessary for children with chronic urticaria to monitor treatment efficacy, assess for side effects, and re-evaluate for underlying causes
For acute urticaria, follow-up may be on an as-needed basis unless complications arise.
Key Points
Exam Focus:
Distinguish acute (<6 weeks) from chronic (>6 weeks) urticaria
Understand that antihistamines (2nd generation preferred) are first-line for both
Consider oral steroids for short-term severe acute flares
Omalizumab is key for chronic spontaneous urticaria refractory to antihistamines
Angioedema requires immediate airway assessment.
Clinical Pearls:
Always ask about recent infections, new medications, and dietary changes
Remember that chronic urticaria can be autoimmune
Consider urticarial vasculitis if lesions persist >24h and are painful
Stress the importance of trigger avoidance and patient education.
Common Mistakes:
Over-reliance on oral steroids for chronic urticaria
Inadequate trial of high-dose antihistamines before escalating treatment
Failure to consider urticarial vasculitis or other differentials
Not investigating for underlying causes in chronic or recurrent cases.