Papillary serous carcinoma of the peritoneum: analysis of clonality of peritoneal tumors.

Papillary serous carcinoma of the peritoneum (PSCP) is a primary neoplasm of peritoneal origin, and is histologically difficult to differentiate from papillary serous carcinoma of the ovary (PSCO). PSCP is frequently accompanied by many peritoneal tumors, and has been managed as a disseminated disease. In previous reports, however, the clonality of the tumors has not been fully discussed. Recently, the significant roles of the p53 and BRCA1 genes in PSCP have been reported. In this study, we investigated immunohistochemical staining for p53 proteins, and investigated p53 gene mutations, using DNA sequencing analysis, to clarify the clonality of PSCP tumors. Immunohistochemically, all the tumor samples demonstrated nuclear overexpression of p53 proteins, and the DNA sequencing analysis of the p53 gene showed diverse point mutations at codons 167 and 192 in two of four anatomically different tumors. In conclusion, the possibility of polyclonality of PSCP tumors is suggested.