Urticaria, Angioedema and Drug Eruptions MCQs

Dermatology · 16 free questions with answers & explanations.

1. A patient on co-trimoxazole for urinary tract infection develops target lesions with three distinct zones (central dark area, pale edematous ring, outer erythematous halo) over palms, soles, and oral mucosa. There is no skin detachment. What is the diagnosis?
2. A 30-year-old woman with chronic spontaneous urticaria is uncontrolled on high-dose second-generation antihistamines (4× standard dose). According to current EAACI/GA²LEN guidelines, the next step in management is:
3. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are distinguished by body surface area of epidermal detachment. What percentage defines TEN?
4. Drug reaction with eosinophilia and systemic symptoms (DRESS/DiHS) has a delayed onset. What is the typical latency period from drug initiation to symptom onset, and which drug is most commonly implicated in India?
5. A 40-year-old woman develops angioedema without urticaria, recurring for 3 years, triggered by ACE inhibitor therapy. She is switched to an ARB but still develops angioedema. What is the most likely mechanism of drug-independent angioedema in this patient?
6. A patient on phenytoin develops a severe cutaneous adverse reaction with >30% BSA epidermal detachment, mucosal involvement, and systemic features. Which HLA allele has the strongest association with this drug-reaction in South and Southeast Asian populations?
7. A patient develops Stevens-Johnson syndrome (SJS) after starting carbamazepine. The HLA allele most strongly associated with carbamazepine-induced SJS in South and Southeast Asian populations is:
8. Fixed drug eruption (FDE) characteristically recurs at the same site with re-exposure to the offending drug. The immunological mechanism responsible for site-specific recurrence is:
9. A patient develops blistering and full-thickness epidermal necrosis affecting 45% body surface area 21 days after starting phenytoin. This clinical picture (TEN - toxic epidermal necrolysis) is primarily mediated by:
10. A 40-year-old man on ACE inhibitor for hypertension presents with recurrent episodes of massive swelling of lips, tongue, and periorbital tissue without urticaria or pruritus. The mechanism underlying this drug-induced angioedema is:
11. Stevens-Johnson syndrome (SJS) is distinct from toxic epidermal necrolysis (TEN) primarily by the percentage of body surface area with epidermal detachment. The defining parameter and the most common triggering drug class are:
12. Fixed drug eruption (FDE) is characterised by recurrence at the same site on re-exposure. The causative drug most classically associated with FDE is:
13. A 38-year-old woman on lisinopril develops recurrent episodes of painless, non-pruritic facial angioedema without urticaria. Which mechanism explains this ACE inhibitor-induced angioedema?
14. A 40-year-old woman has chronic spontaneous urticaria (CSU) for 8 months. She is on maximally dosed non-sedating H1-antihistamines (cetirizine 20 mg/day) without adequate control. She has positive autologous serum skin test (ASST). The next appropriate step per current EAACI guidelines is:
15. A patient with chronic spontaneous urticaria (CSU) fails to respond to high-dose cetirizine (20 mg/day). The next step according to EAACI/WAO guidelines is:
16. A fixed drug eruption (FDE) leaves a residual hyperpigmented patch. The drug most commonly responsible for FDE in India is: