ABSTRACT
A 6-year-old child is assessed in the accident and emergency department, where his parents give a 1-week history of drowsiness, headache and generalised weakness. His parents concede that he has been generally unwell for 3–4 months, with tiredness and fever. On examination, he is pyrexial (38°C) and clearly drowsy, though he responds to verbal commands. He has generalised muscle weakness. There is no neck stiffness. Reflexes are normal and both plantar responses are equivocal. He has generalised lymphadenopathy and liver and spleen are both palpable. His full blood count shows
