Drug eruptions including DRESS and AGEP — branching viva

Examiner opening (Examiner)

You are the general paediatric registrar on the ward. A seven-year-old boy who started phenytoin for new-onset epilepsy six weeks ago presents with a fever of 39 degrees, a widespread red rash, facial swelling, enlarged cervical lymph nodes, and blood tests showing eosinophilia and a hepatitis with raised transaminases. Talk me through your assessment and your working diagnosis. ^[2]

Exemplar opening (Candidate)

This is DRESS — drug reaction with eosinophilia and systemic symptoms, also called drug-induced hypersensitivity syndrome — until proven otherwise, caused by the phenytoin he started six weeks ago. The combination of the long latency of two to eight weeks, the fever, the facial oedema, the lymphadenopathy, the eosinophilia and the hepatitis is the classic presentation of a severe cutaneous adverse reaction to an aromatic anticonvulsant. My immediate priorities are to stop the phenytoin, to assess his airway breathing and circulation, to exclude sepsis with cultures, and to confirm the pattern of organ involvement, because this is not a simple drug allergy — it carries up to ten per cent mortality and can relapse. ^[2]