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Bullous Pemphigoid — RACP Adult Medicine MCQ

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ModerateDermatologyBullous PemphigoidRACP Adult Medicine

A 78-year-old woman presents with large tense bullae on her trunk and limbs with surrounding urticarial plaques. Nikolsky sign is negative. Direct immunofluorescence shows linear IgG and C3 along the dermal-epidermal junction. What is the diagnosis?

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Correct answer: A — Bullous pemphigoid

Tense bullae (as opposed to flaccid in pemphigus) on a urticarial base in an elderly patient with linear IgG/C3 at the basement membrane zone is diagnostic of bullous pemphigoid. Anti-BP180 and anti-BP230 antibodies target hemidesmosomes. Nikolsky sign is negative because the blister is subepidermal. First-line treatment is potent topical corticosteroids (clobetasol) for moderate disease or systemic corticosteroids plus doxycycline or dapsone for extensive disease.

Reference: eTG – 2025 – Dermatology; BAD – 2017 – Bullous Pemphigoid Guidelines