Serous papillary carcinomas arising from the peritoneum and ovaries. A clinicopathologic and immunohistochemical comparison.

Primary papillary serous carcinoma arising from the peritoneal surface (serous surface papillary carcinoma; SSPC) is a distinctive neoplasm with a histomorphologic resemblance to serous ovarian papillary carcinoma (SOPC). To determine if these tumors are similar antigenically, we studied 13 examples of SSPC and 31 of SOPC immunohistochemically. Antibodies to several determinants known to occur in the Müllerian epithelium were employed. Both neoplasms were uniformly positive for cytokeratin and epithelial membrane antigen (EMA); in addition, SSPC and SOPC were similar in quantitative and qualitative reactivity for B72.3 antigen, carcinoembryonic antigen, Leu M1, CA-125 antigen, LN1, LN2, MB2, S100 protein, placental alkaline phosphatase, and amylase. Residual nonneoplastic mesothelium failed to express any of these antigens except for cytokeratin, EMA, and CA-125. The clinical behavior of SSPC was similar to that of high-stage SOPC; all patients with adequate follow-up died of their tumors. These results suggest that SSPC and SOPC are analogous lesions, with respect to their cellular differentiation. Moreover, it would appear that both neoplasms display only a limited immunophenotypic homology to the mesothelium.