Heads up: don't forget the ordinary.

A 72-year-old woman presented to the emergency department with shortness of breath, diffuse swelling and a haemoglobin of 4.2 g/dl. Her history was notable for an unusual necrotic occipital neck mass that had begun to enlarge and intermittently bleed over the past year. The patient was initially unable to tolerate a CT scan because of the neck mass, and care was further complicated by extended boarding for more than 24 h in the emergency department. Initial fevers were attributed to blood transfusion, but she subsequently developed septic shock and disseminated intravascular coagulation from Escherichia coli bacteraemia, which led to anuric renal failure requiring haemodialysis. When the CT was performed, it revealed an obstructing ureteric stone which was the source of her infection, not the neck mass as had been assumed. This case underscores the importance of maintaining a broad and impartial differential diagnosis.