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Concurrent Contact Dermatitis — SCE Dermatology MCQ

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HardInflammatory DermatosesConcurrent Contact DermatitisSCE Dermatology

A 45-year-old woman with psoriasis on a biologic develops a new rash. It is a widespread eczematous eruption that differs morphologically from her psoriasis (spongiotic rather than psoriasiform histology). She has recently changed her laundry detergent. What should be considered?

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Correct answer: C — Superimposed allergic contact dermatitis on pre-existing psoriasis — patch testing should be performed

The best answer is “Superimposed allergic contact dermatitis on pre-existing psoriasis — patch testing should be performed”. NICE recommends treatment matched to severity, high-impact sites, functional burden, comorbidity and prior response; narrowband UVB is a finite specialist option for plaque or guttate psoriasis that topical therapy cannot control. The alternatives “The biologic has caused eczema, after specialist assessment, when the full phenotype supports it”, “Drug eruption from the biologic, when the full phenotype supports it”, “The psoriasis has changed morphology, within an appropriate UK pathway, after clinicopathological correlation”, “She has developed CTCL, after clinicopathological correlation, after specialist assessment, when the full phenotype supports it” are clinically adjacent possibilities, but they do not fit the defining morphology, distribution, histopathology, risk signal or management sequence in this stem.

Reference: NICE CG153 psoriasis recommendations: https://www.nice.org.uk/guidance/cg153/chapter/Recommendations