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Atopic Eczema — SCE Dermatology MCQ

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ModerateInflammatory DermatosesAtopic EczemaSCE Dermatology

A 22-year-old woman with atopic eczema has been referred for allergy testing. Skin prick testing shows a 6 mm wheal to house dust mite (positive control histamine 4 mm). What does this indicate?

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Correct answer: E — IgE sensitisation to house dust mite (but clinical relevance must be correlated with history)

A positive skin prick test (wheal ≥3 mm larger than negative control) indicates IgE sensitisation (presence of specific IgE antibodies) but does NOT prove clinical allergy. Clinical relevance must be assessed by correlating the test result with the patient's history — does exposure to the allergen reliably worsen symptoms? In atopic eczema, aeroallergen sensitisation (HDM, pet dander, pollen) is common but does not always indicate clinical trigger. Specific IgE testing/SPT should not lead to blanket avoidance recommendations without clinical correlation. HDM avoidance measures have shown inconsistent benefit for eczema in clinical trials.

Reference: NICE CG57; BAD AD Guidelines; BSACI