skip to main content

Melanonychia — SCE Dermatology MCQ

Instant feedback + full explanation. One question, done properly.

HardNail DisordersMelanonychiaSCE Dermatology

A 30-year-old woman presents with a pigmented streak on her nail (melanonychia). Dermoscopy of the nail plate (onychoscopy) shows a brown band with regular parallel lines of uniform colour, spacing, and thickness. What does this pattern suggest?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Benign melanocytic activation or naevus (regular pattern)

The best answer is “Benign melanocytic activation or naevus (regular pattern)”. Nail findings localise disease to matrix, bed or periungual tissue; a new changing longitudinal pigmented or erythronychic band requires specialist assessment because benign and malignant causes overlap. The alternatives “Fungal infection, after specialist assessment”, “Subungual haematoma, when the full phenotype supports it”, “Bacterial infection, within an appropriate UK pathway”, “Melanoma, after clinicopathological correlation, after specialist assessment” are clinically adjacent possibilities, but they do not fit the defining morphology, distribution, histopathology, risk signal or management sequence in this stem.

Reference: DermNet specialist nail terminology reference: https://dermnetnz.org/topics/nail-terminology