As with all mesotheliomas, the diagnosis of peritoneal mesothelioma can be challenging. CT findings may help differentiate between the two clinical types of peritoneal mesothelioma, termed “dry” or “wet”, since their appearances are very different upon imaging. In the “dry” type, CT may reveal multiple small masses or a single dominant localized mass. There is normally little or no ascites. In the “wet” type, CT may reveal widespread small nodules, but no dominant mass. Ascites is usually present.

If fluid is present, it may be removed in a procedure called paracentesis. Unfortunately, as is the case with pleural mesothelioma, fluid analysis offers limited diagnostic value. It is normally a tissue biopsy obtained in a laproscopic exploratory that will yield a definitive diagnosis.