A difficult case of fever of unknown origin.

A 57-year-old holidaymaker in Madeira was airlifted to England with a 4-week history of fever, limb weakness and hypophonia. Having undergone a range of investigations during his hospital admission abroad - including ultrasound, CT, echocardiogram and lumbar puncture - the patient arrived without any explanatory diagnosis. At presentation, the only investigatory positives were raised blood inflammatory markers and a, previously unidentified, 'old left frontal infarct' found on head CT. A broad infective and immunological screen proved negative, raising the possibility of vasculitis. Finally, the presence of subacute cerebral and renal infarcts identified on MRI and CT in combination with a negative antineutrophil cytoplasmic antibodies (ANCA) test and distinctive muscle biopsy features confirmed the clinical suspicion of polyarteritis nodosa. An immunosuppressive regime of glucocorticoid therapy and cyclophosphamide were initiated with immediate significant clinical improvement.