Serous tumors of low malignant potential of the ovary. 1. Diagnostic pathology.

Serous ovarian tumors of low malignant potential (SLMP)--also called borderline tumors of the ovary--represent a heterogeneous group of ovarian epithelial neoplasms. In general, this tumor type has a favorable prognosis. Nevertheless, 10-20% of SLMP exhibit a progressively worsening clinical course, with widespread peritoneal implants and death of the patient within 5 years. The criteria for recognizing the SLMP with an unfavorable prognosis and for distinguishing SLMP from highly differentiated ovarian carcinomas are summarized in this report. The importance of supporting methods, e.g., DNA cytophotometry, is demonstrated, revealing that in most cases aneuploidy can be regarded as an indicator for aggressiveness of the tumor and for poor clinical outcome. The importance of the new concept of micropapillary serous carcinomas (MPSC), the relationship of this variant of SLMP to invasive serous carcinomas, and the prognostic importance of invasive vs noninvasive peritoneal implants are discussed. (The concepts of molecular pathology of SLMP will be discussed in part 2 of this serial paper.)