[Useful CT findings in a case of idiopathic perforation of the descending colon].

Idiopathic perforation of the descending colon is an uncommon disease. The disease has tendency to complicate with severe pan-peritonitis at relatively early stage. So early diagnosis and treatment is required. We encountered a 83-years-old female patient with idiopathic perforation of the descending colon. CT revealed the findings suggestive of free air in the retro-peritoneal space. We thought CT may be useful diagnostic approach to make correct diagnosis of the perforation of the colon.