P0184 - A Rare Presentation of Colon Cancer Presenting as a Pseudomonas Intraabdominal Abscess With Perforation and Fluid Collection Post Tumor Resection

Mohammed Ansari, MD¹, Manjot Malhi, MD², Akiva J. Marcus, MD, PhD^3
1University of Central Florida College of Medicine, Ocala, FL; ²University of Central Florida College of Medicine, Gainesville,, FL; ³University of Miami, JFK Medical Center Palm Beach, West Palm Beach, FL

Introduction: We present a case of adenocarcinoma of the colon with perforation and abscess formation. On endoscopy, the mass appeared as two distinct masses in the colon but surgery revealed a single continuous mass with extension to the retroperitoneum.

Case Description/Methods: We present a case of adenocarcinoma of the colon which initially presented as right abdominal pain associated with nausea, vomiting, right flank pain and swelling. A computed tomography (CT) scan of the abdomen and pelvis with contrast showed a 12.9 x 8.2 cm abscess in the posterior pararenal space, with asymmetric wall thickening of the cecum. Colonoscopy revealed a non-obstructing polypoid/ulcerated mass in the mid transverse colon, proximal colon revealed an obstructing infiltrative mass in the mid ascending colon. Visual inspection during surgery confirmed that the large mass originated in the ascending colon, extruded out of the lumen and traversed along the colon through the back wall and eroded back into the right/transverse colon with extension into the retroperitoneum as an abscess. Pathology confirmed moderately differentiated adenocarcinoma. The abscess was drained and cultures grew Pseudomonas aeruginosa, Escherichia coli and Streptococcus constellatus. Thirteen months later the patient returned with nausea, vomiting and decreased appetite. Repeat CT of the abdomen with contrast showed a small amount of gas in the peritoneal cavity, complex fluid density in the right flank with extension into the retroperitoneum, dilatation of small bowel with diffuse stasis of the contents with elevated CEA levels. The collection was drained percutaneously and a drain was placed.



Discussion: The pathogenesis of abscess formation from perforated colon cancer includes fistula formation between the colon and the adjacent structures or direct tumor invasion. The most common site of abscess formation is the peritoneal cavity, but abscesses have also been reported in the retroperitoneum, the abdominal wall, psoas muscle, and the pelvic floor. Facultative aerobes such as Pseudomonas species are rarely discovered in an anaerobic environment. Colonic perforation from adenocarcinoma is a rare occurrence, with perforation occurring in 2.5% to 10% of patients, abscess post perforation is also infrequent occurring at a rate of 0.3% to 4% but infection of the abscess with Pseudomonas has not been reported in our literature review.


Figure: Figure 1: Large obstructing ascending colon mass. Figure 2: Large ascending colon mass after biopsy and tattoo. Figure 3: CT abdomen with contrast showing free air in the peritoneum (blue arrow) and abscess in the right retroperitoneum (red arrow). Figure 4 & 5: Right transverse colon mass. FIgure 6:Transverse colon mass after tattoo.


Disclosures:
Mohammed Ansari indicated no relevant financial relationships.
Manjot Malhi indicated no relevant financial relationships.
Akiva Marcus indicated no relevant financial relationships.


Mohammed Ansari, MD¹, Manjot Malhi, MD², Akiva J. Marcus, MD, PhD³. P0184 - A Rare Presentation of Colon Cancer Presenting as a Pseudomonas Intraabdominal Abscess With Perforation and Fluid Collection Post Tumor Resection, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.