Pneumatosis intestinalis and pneumoperitoneum due to a solitary sigmoid diverticulum.

A man aged 75 developed abdominal pain during treatment with steroids for periarteritis nodosa. Laparotomy disclosed air in the peritoneum, and a section of the sigmoid colon contained numerous airfilled cysts and the mesocolon was emphysematic. A solitary diverticulum communicated with a fistula extending into the mesocolon. Neither inflammation, nor other diverticula were seen at the histological examination.