OSCE — Subcorneal pustular dermatosis (Sneddon-Wilkinson disease)

Brief (to candidate)

You will assess a patient with a presentation consistent with Subcorneal pustular dermatosis (Sneddon-Wilkinson disease).
You have 8 minutes to take a focused history, outline examination, investigations, and management including red flags.

Clinical context

Subcorneal pustular dermatosis (Sneddon-Wilkinson disease) is a chronic, relapsing neutrophilic dermatosis presenting with flaccid pustules in annular/polycyclic patterns on intertriginous skin (groin, axillae, submammary). Histology shows a subcorneal pustule filled with neutrophils with no acantholysis. Direct immunofluorescence is NEGATIVE — the key feature distinguishing classical SPD from IgA pemphigus (identical clinicopathology but DIF-positive for intercellular IgA). Associated with IgG monoclonal gammopathy. First-line treatment is dapsone 50 to 150 mg daily (check G6PD first); alternatives include acitretin, phototherapy, colchicine, ciclosporin and biologics.

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]