Dermatology · UKMLA & AKT
Allergic contact dermatitis
A free high-yield preview for the UKMLA Applied Knowledge Test, covering how to recognise this condition. The full SA Note notes add investigations, management and complications, with practice questions on this topic.
Key high-yield points
- ACD = Type IV (delayed-type) hypersensitivity - T-cell mediated, no antibodies involved
- Sensitisation phase (clinically silent): allergen → Langerhans cell antigen presentation → memory T-cells generated
- Elicitation phase: re-exposure → memory T-cell activation → cytokine release → eczematous rash after 24-72 hours
- Patient may use a product for months/years before sensitisation - absence of previous reaction does NOT exclude ACD
- Common allergens: nickel (most common - jewellery, watches, belt buckles), rubber/latex (condoms, gloves), paraphenylenediamine/PPD (hair dye, black henna), fragrances, acrylates, preservatives (methylisothiazolinone), topical medications (neomycin, lanolin)
Latex condoms are an important cause of pruritus vulvae - contact dermatitis is the most common cause of pruritus vulvae overall.
Unlock the full Allergic contact dermatitis revision
Get the complete high-yield notes (3 more sections covering investigations, management and complications), practice questions, mock exams and Sal, the AI tutor. Start free.