Dermoscopy Rosettes — SCE Dermatology MCQ

Correct answer: A — Keratin at adnexal openings creates four bright points under cross-polarisation

A is correct. Rosettes are four bright white dots arranged like a four-leaf clover and are best seen with polarised dermoscopy. They are thought to arise when crossed polarisation interacts with concentric keratin or fibrosis around adnexal openings. They are common in actinic keratosis and squamous neoplasia but are not disease-specific. Dermal melanophages cause grey or blue dots and peppering, rete ridges create a pigment network, urate is not the usual substrate, and thrombosed capillaries appear red-black rather than shiny white. Interpretation therefore depends on the complete clinical and dermoscopic context rather than using rosettes as a standalone diagnosis.

Reference: DermNet actinic keratosis dermoscopy: https://dermnetnz.org/topics/actinic-keratosis-dermoscopy