Some people will not have any of these symptoms, so pseudomyxoma peritonei can be difficult to diagnose. In women, this type of cancer can sometimes be confused with ovarian cancer because ovarian cancer may also cause a swollen abdomen. Some types of ovarian cancer cells also produce mucin. Often, it is only after an operation to look into the abdomen (a laparotomy) that pseudomyxoma peritonei is properly diagnosed.