Pseudomyxoma peritonei with high serum CA19-9: report of three cases.

Pseudomyxoma peritonei (PMP) is an unusual form of intraabdominal neoplasm that produces a large amount of extracellular mucin. It is often associated with mucinous tumors of gastrointestinal tract or ovary. Herein, we report 3 patients with pseudomyxoma peritonei with high serum carbohydrate antigen 19-9 (CA19-9) levels. The first patient, who had a CA19-9 level of 1132 U/ml, had well-differentiated rectal cancer and died of chemotherapy complications, pneumonia and septic shock; one month after admission. The other 2 cases with CA19-9 levels of 2520 U/ml and 679 U/ml had tumors of unknown origins and had survived more than 1 year and 3 months after treatment, respectively. Usually, elevated serum CA19-9 levels are found in patients with pancreatic, biliary, colorectal, gastric or liver cancers. However, many studies have shown high serum CA19-9 levels are associated with mucinous carcinoma. Immunochemical studies also showed positive staining of CA19-9 in mucinous tumors. PMP is composed of large amounts of mucin, therefore, we suggest that serum and ascites CA19-9 levels should be routinely checked in patients with PMP.