Images of Malignancy: Case 4 Peritoneal Carcinomatosis

Vague abdominal pain, malaise, anorexia, and the loss of 10 lb in 2 months prompted a 65-year-old man to seek medical evaluation. A year earlier he had undergone surgery for stage III carcinoma of the sigmoid colon. Because metastases to the lymph nodes were found in the resected colon, the patient was given postoperative chemotherapy. Histologic examination revealed poorly differentiated adenocarcinoma. Mild diffuse abdominal tenderness was the only significant physical finding. Laboratory test results revealed mild anemia and a markedly elevated carcinoembryonic antigen (CEA) level. A CT scan of the abdomen and pelvis showed enhancing, multiple, small nodules along the anterior abdominal peritoneal surface (A, arrows) and irregular thickening of the omentum (B, arrows). Results of a colonoscopy were unremarkable. Widespread peritoneal carcinomatosis was diagnosed. Despite improvements in perioperative mortality and overall survival for patients who undergo resection for colorectal cancer, the disease can recur.¹ The risk of recurrence is dependent on the cancer’s stage and site; additional risk factors include:

• The presence of a malignant obstruction.
• Poor cell differentiation on histologic examination.
• Mucin production by the tumor cells.
• Lymphatic and vascular invasion by cancer cells.

Most recurrences are within 2 to 3 years after the original cancer surgery and involve the original site or such organs as the liver, lungs, and bone. Peritoneal carcinomatosis involves widespread diffuse metastases to the peritoneal surfaces. The prognosis is extremely poor. Physical examination is not elucidating unless the patient has bowel obstruction or ascites. An elevated CEA level and characteristic CT findings—such as enhancing nodules, a soft tissue mass along the peritoneal surfaces, and ascites—aid in making the diagnosis. Omental involvement may be depicted on CT scan as a solid mass (described as an omental cake) or multiple, small, ill-defined, solid nodules scattered throughout the omentum, which cause a thickened or smudged appearance. Malignant tumoral seeding of the peritoneum most frequently originates from primary ovarian, colonic, and gastric cancers. Less common primary sites include the pancreas, uterus, and bladder. This patient received palliative chemotherapy. He died of the disease 4 months later.