Images of Malignancy: Case 4 Peritoneal Carcinomatosis

Vague abdominal pain, malaise, anorexia,and the loss of 10 lb in 2months prompted a 65-year-old manto seek medical evaluation. A yearearlier he had undergone surgery forstage III carcinoma of the sigmoidcolon. Because metastases to thelymph nodes were found in the resectedcolon, the patient was given postoperativechemotherapy. Histologicexamination revealed poorly differentiatedadenocarcinoma.Mild diffuse abdominal tenderness was the only significantphysical finding. Laboratory test results revealedmild anemia and a markedly elevated carcinoembryonicantigen (CEA) level. A CT scan of the abdomen and pelvisshowed enhancing, multiple, small nodules along the anteriorabdominal peritoneal surface (A, arrows) and irregularthickening of the omentum (B, arrows). Results of acolonoscopy were unremarkable. Widespread peritonealcarcinomatosis was diagnosed.Despite improvements in perioperative mortality andoverall survival for patients who undergo resection for colorectalcancer, the disease can recur.¹ The risk of recurrenceis dependent on the cancer's stage and site; additionalrisk 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 theoriginal cancer surgery and involve the original site orsuch organs as the liver, lungs, and bone.Peritoneal carcinomatosis involves widespread diffusemetastases to the peritoneal surfaces. The prognosis isextremely poor. Physical examination is not elucidating unlessthe patient has bowel obstruction or ascites. An elevatedCEA level and characteristic CT findings--such asenhancing nodules, a soft tissue mass along the peritonealsurfaces, and ascites--aid in making the diagnosis. Omentalinvolvement may be depicted on CT scan as a solidmass (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 ofthe peritoneum most frequently originatesfrom primary ovarian, colonic,and gastric cancers. Less commonprimary sites include the pancreas,uterus, and bladder.This patient received palliativechemotherapy. He died of the disease4 months later.