OSCE — Erythema annulare centrifugum (EAC)

Brief (to candidate)

You will assess a patient with a presentation consistent with Erythema annulare centrifugum (EAC).
You have 8 minutes to take a focused history, outline examination, investigations, and management including red flags.

Clinical context

Erythema annulare centrifugum (EAC) is a figurate (annular or polycyclic) erythema characterised by slowly expanding, erythematous rings with a pathognomonic TRAILING SCALE — a fine scale located just INSIDE the advancing inner edge. It is a reactive type IV hypersensitivity reaction to a distant antigen, most often a dermatophyte (tinea) producing an id reaction, but also drugs, infections, foods, and rarely underlying malignancy (paraneoplastic 'PEACE'). Histology shows the classic 'coat-sleeve' tight perivascular lymphocytic infiltrate. Management is to identify and treat the underlying trigger; EAC is self-limiting but runs a chronic, relapsing course over weeks to months.

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]