Questions and Answers
Which condition is characterized by round or oval erythematous papules or plaques with a collarette scale?
What symptom is most commonly associated with pityriasis rosea?
What is the characteristic pattern of lesions seen in pityriasis rosea along the trunk?
Which of the following treatments is commonly used for pityriasis rosea?
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Which infectious agents are commonly associated with pityriasis rosea?
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What is the most common drug class associated with Stevens-Johnson syndrome?
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Which test is NOT part of the routine diagnostic tests for chronic urticaria?
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Which factor serves as an eliciting stimulus for cholinergic urticaria?
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What underlying condition significantly increases the risk of developing Stevens-Johnson syndrome?
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Which of the following is a first-line treatment for acute urticaria?
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Study Notes
Diagnostic Tests for Urticaria
- Acute Urticaria: No routine or extended diagnostic tests recommended.
-
Chronic Urticaria:
- Routine: Complete Blood Count (CBC), Erythrocyte Sedimentation Rate (ESR) or C-Reactive Protein (CRP).
- Extended: Autologous serum skin test, tests for infections (H. pylori, HBV, HCV), thyroid function tests, pseudoallergen-free diet for 3 weeks, skin biopsy, Antinuclear Antibody (ANA) test.
Inducible Urticaria Testing
- Acquired Cold Urticaria: Cold provocation test using ice cube for 20 minutes; also consider differential blood count, ESR, CRP, and cryoproteins.
- Delayed Pressure Urticaria: Pressure test (0.2-1.5 kg/cm² for 10-20 minutes); no extended tests needed.
- Heat Urticaria: Heat provocation test; no extended tests needed.
- Solar Urticaria: Test with UV and visible light; rule out other light-induced skin conditions.
- Dermographic Urticaria: Elicit dermographism; consider differential blood count, ESR, and CRP for extended diagnosis.
Testing for Other Types of Urticaria
- Aquagenic Urticaria: Wet cloth application at body temperature for 20 minutes; no extended tests required.
- Cholinergic Urticaria: Triggered by exercise and hot baths; no extended tests required.
- Contact Urticaria: Prick test read after 20 minutes; no extended tests required.
- Exercise-Induced Urticaria: Based on history; exercise test with or without food; no extended tests required.
Management Strategies
- Identify and eliminate underlying causes of urticaria.
- Avoid or eliminate eliciting stimuli.
- Inhibit mast cell mediators.
- Use first-generation H1 antihistamines (chlorpheniramine, hydroxyzine) for acute urticaria.
- For chronic urticaria, second-generation H1 antihistamines (cetirizine, loratadine, etc.) are first-line due to better safety profiles.
Erythema Multiforme (EM)
- Characterized by mucosal involvement (eyes, mouth, genitalia, perianal area).
Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN)
- Drug-induced reactions common with antibiotics (e.g., sulfonamides), anticonvulsants (carbamazepine), allopurinol, and NSAIDs.
- Infection triggers: herpes, mycoplasma, HIV significantly increases risk.
- Autoimmune disease predispositions: methotrexate, cyclosporine, biologics.
Pityriasis Rosea
- Age group: 10-35 years, affect both sexes equally.
- Course duration: Usually 6-8 weeks.
- Etiology: Associated with infectious agents like HHV-7 and occasionally HHV-6.
- Clinical features include round or oval erythematous papules with collarette scale, herald patch present in 50-90% of cases.
- Distinct "Christmas tree" pattern along skin creases; may present with itching, fever, malaise.
Urticaria Definition and Characteristics
- Urticaria presents as wheals and/or angioedema.
- Wheals are central swellings with surrounding erythema, itchy, returning to normal appearance within 1-24 hours.
- Angioedema involves sudden, pronounced swelling of the lower dermis and subcutis, often affecting mucous membranes.
Skin Lesions and Disease Patterns
- Primary Skin Lesions: Changes in skin surface with secondary lesions (scales, erosions).
- Scale Types: Thick silvery scale (psoriasis), fine wrinkle scale (pityriasis versicolor), fish-like scale (ichthyosis), greasy scale (seborrheic dermatitis), collarette scale (pityriasis rosea).
- Distribution patterns: along skin creases (Christmas tree configuration), photodistribution sparing certain areas, airborne contact dermatitis affecting broad regions.
Maculopapular Rash Causes
- Often linked to drug eruptions, autoimmune diseases, or systemic infections leading to viral exanthems.
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Description
Test your knowledge on recommended diagnostic tests for allergies based on the guidelines from Zuberbier et al. This quiz covers both spontaneous and routine diagnostic tests for acute and chronic urticaria. Challenge yourself to understand the necessary evaluations and approaches in allergy diagnosis.
