Nikolsky Sign — MFDS Part 1 MCQ
Instant feedback + full explanation. One question, done properly.
Educational content. Not a substitute for clinical judgement or local policy.
Reveal the answer and explanation
Correct answer: D — Pemphigus vulgaris
Pemphigus vulgaris is the condition most characteristically associated with a positive oral Nikolsky sign: gentle tangential pressure causes clinically normal or perilesional epithelium to separate. Autoantibodies against desmosomal adhesion proteins cause suprabasal acantholysis and loss of keratinocyte cohesion, producing fragile intraepithelial blisters that rapidly become erosions. The sign supports, but does not confirm, the diagnosis; biopsy for histopathology and direct immunofluorescence is required. Bullous or erosive lichenoid disease can occasionally produce a positive sign, but conventional lichen planus is not the classic association. Aphthous ulceration, geographic tongue and oral candidiasis do not characteristically cause pressure-induced epithelial separation.
Reference: Kayani M, Aslam AM. Bullous pemphigoid and pemphigus vulgaris, examination findings and Nikolsky sign. BMJ. 2017;357:j2169. https://pubmed.ncbi.nlm.nih.gov/19053912/