DR14.1-3 | Urticaria Angioedema — Practice Quiz

Correct. Individual wheal resolution within 24 hours without post-inflammatory change is the hallmark that separates ordinary urticaria from urticarial vasculitis. Pruritus, symmetry, and distribution are unhelpful discriminators.

Urticaria wheals resolve completely within <24 hours leaving no residual marks; urticarial vasculitis lesions persist >24 h and resolve with bruising/hyperpigmentation.

Reconsider. The morphological behaviour over time — not the itch or distribution — is what distinguishes urticaria from urticarial vasculitis. Think about what happens to the skin after a wheal resolves in each condition.

Correct. Duration ≥6 weeks classifies urticaria as chronic; the absence of a reproducible physical stimulus makes it spontaneous, not inducible.

Urticaria ≥6 weeks = chronic; no reproducible physical trigger = spontaneous. The two axes (duration and presence of inducible trigger) are independent.

Remember the two independent axes: duration (acute <6 weeks, chronic ≥6 weeks) and trigger pattern (spontaneous = no consistent physical trigger, inducible = physical stimulus reliably provokes wheals). Apply both axes to this case.

Correct. H1-receptor activation on postcapillary venule endothelium drives vasodilation and increased permeability; the resulting plasma transudation into the superficial dermis creates the wheal.

Histamine acting on H1 receptors on postcapillary venules causes vasodilation and increased permeability → plasma transudation into the superficial dermis forming the wheal.

Think through the direct effect of histamine on blood vessel calibre and wall permeability. The wheal is oedema — excess fluid in the tissue — so the vascular changes must increase fluid movement out of the vessel.

Correct. Symptomatic dermographism presents as itchy linear wheals appearing within minutes of skin stroking or friction from clothing, resolving in 20–30 minutes. It is the commonest inducible physical urticaria.

Dermographism (symptomatic) = reproducible itchy linear wheals at sites of skin stroking/friction; onset within minutes, resolves within 30 minutes. It is the commonest inducible urticaria.

Focus on the trigger: linear friction/stroking producing a linear wheal. Each physical urticaria has a unique provoking stimulus — match the clinical description to the correct trigger type.

Correct. In angioedema without airway compromise or hypotension, parenteral antihistamine and close monitoring are appropriate. Adrenaline is life-saving in anaphylaxis (stridor, hypotension, collapse) but is not first-line for isolated facial/lip angioedema with a maintained airway.

Angioedema without airway compromise or anaphylaxis: parenteral antihistamine + close monitoring. Adrenaline is reserved for airway compromise/anaphylaxis. Alert, normotensive, no stridor = not yet anaphylaxis.

Assess severity first: is there airway compromise? Stridor, hypotension, or deteriorating consciousness mandate immediate adrenaline. In this patient the airway is currently intact, but close monitoring is essential because angioedema can progress rapidly.

Correct. Guidelines (EAACI, IADVL) recommend second-generation non-sedating H1-antihistamines (cetirizine, loratadine, fexofenadine, levocetirizine, desloratadine) as first-line due to superior side-effect profile.

Second-generation non-sedating H1-antihistamines are first-line for chronic urticaria; first-generation antihistamines are NOT recommended first-line due to sedation, cognitive impairment, and anticholinergic effects.

Recall the management ladder for chronic urticaria. First-generation antihistamines are not recommended first-line because of significant sedation and anticholinergic effects. Think about which generation of antihistamines has the better safety and tolerability profile.

Correct. ACE inhibitors block kininase II (= ACE), impairing bradykinin degradation. Bradykinin excess causes angioedema via bradykinin B2 receptors on endothelium — this is NOT histamine-mediated, so antihistamines and corticosteroids are ineffective. Stopping the ACE inhibitor is the treatment.

ACE-inhibitor angioedema is bradykinin-mediated (ACE also degrades bradykinin); it is NOT histamine-driven and therefore NOT responsive to antihistamines or corticosteroids. Key: no wheals, normal tryptase, antihistamine-refractory.

The antihistamine failure is the critical clue. If angioedema does not respond to antihistamines, the mediator is not histamine. Consider which drugs or genetic defects cause bradykinin-mediated angioedema, and recall that ACE is the enzyme that degrades bradykinin.

Correct. The diagnostic criterion for symptomatic dermographism is a raised, linear, pruritic wheal appearing within minutes of a firm stroke. Itch is the key discriminator from simple (factitious) dermographism, where a non-itchy wheal may be a normal physiological variant.

Symptomatic dermographism = pruritic (itchy) linear wheal after skin stroke. A non-itchy wheal (simple/factitious dermographism) is a physiological variant seen in ~5% of the population. The itch distinguishes pathological from physiological.

Pay attention to whether the wheal itches. A non-itchy wheal after stroking is called simple dermographism and may be seen in normal individuals. It is the itch that makes the response symptomatic (pathological) and clinically relevant.

Correct. Omalizumab 300 mg SC every 4 weeks is the evidence-based Step 3 treatment for chronic spontaneous urticaria refractory to up-dosed second-generation antihistamines. It works by reducing free IgE and downregulating FcεRI on mast cells.

Omalizumab (anti-IgE) is the EAACI Step 3 therapy for antihistamine-refractory chronic spontaneous urticaria. Long-term corticosteroids are not recommended; extensive allergy testing rarely changes management in CSU.

Follow the treatment ladder: Step 1 = standard-dose 2nd-gen antihistamine → Step 2 = up-dosed (×4) 2nd-gen antihistamine → Step 3 = omalizumab. Chronic corticosteroids are not part of the ladder due to unacceptable long-term adverse effects.

Correct. With wheal morphology confirmed (<24 h, no residual mark), the classification axes require knowing the total duration of the illness. Acute urticaria = total duration <6 weeks; chronic = ≥6 weeks. This directly guides investigation intensity and treatment decisions.

Once urticaria morphology is confirmed (transient <24h wheal), the classification axes require: (1) duration of the overall condition (acute <6w vs chronic ≥6w) and (2) whether a physical trigger is present (spontaneous vs inducible).

You have already confirmed this is urticaria (transient wheal <24 h, no residual mark). Now think about what information is needed to classify it — the two axes of the classification system are duration and trigger type. Which question addresses the duration axis?