Gas-Forming Hepatic Metastases Due to Clostridium septicum Infection: A Rare Case Documented with Sequential CT Imaging.

A rare case of hepatic gas-forming metastases secondary to Clostridium septicum infection is described. A 78-year-old woman was admitted with right lower quadrant abdominal pain and deterioration. Initial imaging revealed a right-sided colonic malignancy with hepatic metastases. Follow-up scans showed gas within metastases and minimal pneumoperitoneum, suggesting bowel perforation. However, blood cultures isolated C. septicum, supporting infected necrotic metastases as the source of free gas. Teaching point: This case emphasizes the importance of distinguishing infectious intratumoral gas from perforation in oncological patients and provides one of the few reports with sequential imaging of this process.