OSCE — Blue naevus and dermal melanocytosis

Brief (to candidate)

You will assess a patient with a presentation consistent with Blue naevus and dermal melanocytosis.
You have 8 minutes to take a focused history, outline examination, investigations, and management including red flags.

Clinical context

A blue naevus is a benign melanocytic lesion built from heavily pigmented, dendritic and spindled DERMAL melanocytes in the reticular dermis, whose blue colour is an optical effect (Tyndall scattering) of the deep pigment location rather than blue pigment. The common blue naevus is a small, stable, blue-black papule of the extremities; the cellular blue naevus is a larger, deeper lesion of the buttock, sacrum or scalp with a small malignant potential; and dermal melanocytoses (Mongolian spot, naevus of Ota, naevus of Ito) are persistent ectopic dermal melanocytes distributed by site. Stable classic lesions are observed; any changing or atypical blue lesion is biopsied or excised to exclude melanoma.

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.^[1]