Serous surface carcinoma of the peritoneum: useful role of cytology in differential diagnosis and follow-up

OBJECTIVE: To determine the role of cytology in differentiating serous surface carcinoma of the peritoneum (SSCP) from other morphologically similar tumors, including ovarian carcinoma and other peritoneal lesions, and to define the value of cytology in the follow-up of patients with SSCP. STUDY DESIGN: Twenty-one ascitic fluids and seven peritoneal washings obtained from 19 patients with histologically confirmed SSCP were reviewed and their cytologic features tabulated and analyzed. RESULTS: Eighteen of the specimens were from initial diagnostic paracenteses or exploratory laparotomies. These showed mostly three-dimensional tumor cell clusters, as well as single malignant cells, with occasional papillae. The cytoplasm was abundant and often vacuolated. The cytomorphologic features of SSCP enabled differentiation from other conditions involving the peritoneal surface, including mesothelial hyperplasia, malignant mesothelioma, endometriosis and endosalpingiosis. However, there were no characteristic features that differentiated SSCP from metastatic serous carcinoma of the ovary. Four of the peritoneal washings were from second-look operations; in each of these cases the presence of tumor cells in the cytologic preparations correlated with positive biopsy results. Furthermore, six of the paracenteses were performed for recurrent ascites and enabled detection of recurrent disease, obviating the need for invasive procedures. CONCLUSION: Cytomorphologic examination of ascitic fluids and peritoneal washings serves a valuable role in the initial diagnosis of SSCP, in the detection of recurrent disease and as a useful adjunct to multiple biopsies in the second-look operation. It can differentiate SSCP from several other lesions but not from serous carcinoma of the ovary.