Computed tomographic characterization of malignant peritoneal mesothelioma

Peritoneal mesothelioma is a rare disease with a universally fatal outcome when managed in a traditional palliative manner. New approaches to treatment using cytoreductive surgery and intraperitoneal chemotherapy suggest that long-term survival is possible in selected patients. Early recognition of this disease process with an orderly surgical approach will begin to optimize treatment.

Thirty-three patients with malignant peritoneal mesothelioma had CT scans available for review. A Z-score was used to evaluate the incidence of cancer at a particular anatomic site as compared to a general incidence of disease at all sites. CT was analyzed by abdominopelvic anatomic sites (16), abdominopelvic regions (9), and for presence versus absence of disease in the chest. Interpretative CT findings (class 0-III) were determined for these 33 patients.

Eight of 33 patients had pleural abnormalities. In an analysis of 16 abdominopelvic anatomic sites, the vesical or rectal uterine pouch was involved in 97% and the greater omentum in 91%. These anatomic sites were the only ones with a positive Z-score of >1. In the analysis of 9 abdominopelvic regions, the central and pelvic regions had Z-scores >2 for large volume disease >5 cm. For CT interpretative findings class I, class II and class III was determined in approximately one-third in each category. Sixty-six percent of the patients had ascites by CT.

Malignant peritoneal mesothelioma by CT evaluation predominates in tumor mass within the central and pelvic portions of the abdomen. Minimal, moderate, and extensive small bowel enlargements were seen in roughly one-third of the patients. With the use of the Z-score and interpretative small bowel findings a radiologic characterization of this disease for primary radiologic diagnosis is possible.