Colorectal cancer liver metastasis presenting as pneumoperitoneum: case report and literature review.

Pneumoperitoneum presenting as air under diaphragm on erect chest X-ray is usually a result of hollow viscous perforation but can be a result of many other diagnoses including necrotising enterocolitis and ruptured liver abscess. We report a case of colon cancer with liver metastases presenting as pneumoperitoneum. This was a result of infection of the metastases with Clostridium septicum with resultant rupture in to sub diaphragmatic space.