OSCE — Halo naevus (Sutton's naevus)

Brief (to candidate)

You will assess a patient with a presentation consistent with Halo naevus (Sutton's naevus).
You have 8 minutes to take a focused history, outline examination, investigations, and management including red flags.

Clinical context

Halo naevus (Sutton's naevus, leucoderma acquisitum centrifugum) is a benign acquired melanocytic naevus surrounded by a symmetric, well-demarcated depigmented (white) halo, caused by autoimmune CD8+ cytotoxic T-cell-mediated destruction of both naevus melanocytes and the surrounding normal epidermal melanocytes (target antigens Melan-A/MART-1, gp100, tyrosinase). Prevalence is around 1 per cent, predominantly in children and adolescents (average age 15), on the trunk, and usually multiple. Associated with vitiligo (up to a quarter of cases) and autoimmune thyroid disease (Hashimoto's, anti-TPO). Natural history is benign and self-limiting in four stages: naevus with developing halo, fading

Candidate tasks

1. Clarify onset, severity, associated features, and red-flag symptoms.
2. State focused examination priorities.
3. List first-line investigations and any named score/criteria.
4. Give immediate resuscitation steps.
5. Outline definitive management with doses/routes where standard.
6. Name complications and disposition (ward / HDU / theatre / discharge safety-net).
7. Mention one special-population modifier (pregnancy, child, elderly, CKD).

Examiner checklist

Model outline

Lead with the working diagnosis and life threats. Resuscitate before definitive tests when unstable. Use guideline-standard therapy with named agents and doses. Document escalation criteria and follow-up. A safe candidate is specific, structured, and never delays critical care for non-urgent imaging.^[2]