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Pemphigus Vulgaris — RACP Adult Medicine MCQ

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ModerateDermatologyPemphigus VulgarisRACP Adult Medicine

A 45-year-old woman presents with a widespread blistering eruption on the trunk and limbs. Nikolsky sign is positive. Skin biopsy with direct immunofluorescence shows IgG and C3 deposition in the intercellular spaces of the epidermis in a 'chicken-wire' pattern. What is the diagnosis?

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Correct answer: D — Pemphigus vulgaris

Intercellular IgG and C3 deposition in a 'chicken-wire' (fishnet) pattern on DIF is diagnostic of pemphigus vulgaris. The positive Nikolsky sign reflects intraepidermal acantholysis. Anti-desmoglein 1 and 3 antibodies are the target autoantigens. Treatment involves high-dose corticosteroids and steroid-sparing immunosuppression (rituximab is increasingly used as first-line in severe disease per the RITUX 3 trial).

Reference: eTG – 2025 – Dermatology; BAD – 2017 – Pemphigus Guidelines