Hyperattenuating ring sign.

A 39-year-old man with no medical history complained of right flank pain that developed 1 day prior. He reported no history of sexual activity or of travelling abroad for the past 6 months. His temperature was 38.0°C, his BP was 144/87 mm Hg and his pulse was 119 per minute. Physical examination revealed tenderness in the right flank, with no rebound tenderness. Laboratory evaluation revealed elevated white blood cell count of 12.9×109/L (neutrophils: 67.8%). A right upper quadrant ultrasound …