Eczema, dermatitis & lichenoid flashcards
10 high-yield MRCP Part 1 cards from the Intellect Medicos Dermatology course. Try to answer each question before you open it — then study them properly with spaced repetition, which brings each card back just before you would forget it.
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Topical steroids for atopic eczema by potency: mild = hydrocortisone 1%; moderate = ______; potent = betamethasone valerate 0.1%; very potent = clobetasol propionate 0.05%.
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clobetasone butyrate 0.05%
Why? Match potency to severity: mild steroid for mild eczema, moderate for moderate, potent for severe. Always use with emollients.
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Topical steroids for atopic eczema by potency: mild = hydrocortisone 1%; moderate = clobetasone butyrate 0.05%; potent = ______; very potent = clobetasol propionate 0.05%.
Show answer
betamethasone valerate 0.1%
Why? Match potency to severity: mild steroid for mild eczema, moderate for moderate, potent for severe. Always use with emollients.
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What is the investigation of choice to identify the causative agent in suspected allergic contact dermatitis?
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Patch testing.
Why? Allergic contact dermatitis is a delayed type IV (T-cell mediated) reaction, so the skin is read for a reaction a few days after allergens are applied. Nickel is a common culprit.
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Name three drug groups that can cause a lichenoid (lichen planus–like) drug eruption.
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Any three: ACE inhibitors, beta-blockers, NSAIDs, thiazides, gold, quinine/antimalarials.
Why? Lichenoid eruptions look like lichen planus (purple, polygonal, itchy papules) and usually settle slowly after the drug is stopped.
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What is the first-line treatment for vulval lichen sclerosus?
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A very potent topical corticosteroid — clobetasol propionate 0.05%.
Why? Lichen sclerosus causes itchy porcelain-white atrophic plaques, typically in postmenopausal women (it can also affect children and men).
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Which allergen in permanent hair dye is a common cause of allergic contact dermatitis?
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Paraphenylenediamine (PPD).
Why? It causes scalp, face and eyelid dermatitis after hair dyeing; sensitisation often follows "black henna" tattoos. Patch testing confirms it.
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Which chronic viral infection is associated with lichen planus, especially oral disease?
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Hepatitis C.
Why? Lichen planus gives purple, pruritic, polygonal, planar papules; oral disease shows white lacy Wickham's striae. First-line treatment is a topical corticosteroid.
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What is the first-line treatment for seborrhoeic dermatitis of the scalp?
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Ketoconazole 2% shampoo.
Why? It targets Malassezia yeast overgrowth. Alternatives: selenium sulphide, zinc pyrithione or a topical steroid. On the face and body, a topical imidazole cream is first-line.
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What is the mechanism of action of dupilumab, used for moderate-to-severe atopic eczema?
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Monoclonal antibody against the IL-4 receptor alpha subunit, blocking IL-4 and IL-13 signalling.
Why? It is a NICE-approved option for adults whose eczema has not responded to at least one systemic immunosuppressant (e.g. ciclosporin) or in whom these are unsuitable.
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How do topical tacrolimus and pimecrolimus work, and what is their key advantage over topical steroids?
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They inhibit calcineurin, reducing T-cell activation and IL-2 production; they do not cause skin atrophy.
Why? This makes them useful on the face, eyelids and flexures (eczema, facial psoriasis, vitiligo). A burning sensation on application is common.