Serous surface carcinoma of the peritoneum: a clinicopathologic study of 22 cases

Serous surface carcinoma (SSC) of the peritoneum is defined as a primary tumor histologically indistinguishable from serous carcinoma of the ovary, diffusely involving the peritoneal surface but sparing or only superficially invading the ovaries. In this study of 22 cases of SSC, it was found that the main clinical manifestations of SSC were abdominal pain and enlargement. In most cases, SSC evenly involved the entire mesothelial surface but rarely was predominant in or even limited to the pelvis. It frequently invaded the submesothelium, but deep invasion into abdominal and pelvic organs or local metastasis was rare, and distant metastasis was not seen at presentation. Microscopically, SSC was a high-grade tumor frequently showing high mitotic rate, psammomas bodies, and necrosis. The tumor was usually contiguous with hyperplastic mesothelium on either ovarian surface or other locations. Tumor cells in all cases except one showed cytoplasmic or surface neutral or acidic mucin or both. Tumor cells stained positive for keratin (100% of cases), epithelial membrane antigen (100%), Leu-M1 (45%), B72.3 (85%), vimentin (35%), and carcinoembryonic antigen (25%). Electron microscopic studies of six cases showed epithelial differentiation in each. Seven patients (32%) were alive with no clinical disease at 3 to 31 months, one patient (4%) was alive with extensive local disease at 24 months, 11 patients (50%) died almost exclusively of local recurrence at 1 to 70 months, and three patients (14%) died of operative complications. It is concluded that SSC arises from peritoneal mesothelium but has epithelial phenotype. It can be morphologically differentiated from other conditions with similar laparotomy findings, such as malignant mesothelioma, benign papillary mesothelioma, cystic mesothelioma, and benign or borderline peritoneal serous tumors. The prognosis of SSC is poor, and most patients die of uncontrollable local disease.