An in vitro study of ovarian atypical proliferating (borderline) serous tumors.

Seven human serous ovarian atypically proliferating tumors (tumors of borderline malignancy) were grown in primary culture and compared morphologically with established cell lines derived from serous carcinomas (stage III-IV). Several parameters were investigated in order to establish the place of these tumors in a neoplastic spectrum between benign and frankly malignant serous neoplasms. The atypically proliferating tumors showed serous features, including prominent microvilli and multiple cilia, similar to those found in the malignant serous cells. DNA flow cytometric studies of the atypically proliferating tumors showed them to be diploid. Keratins were strongly expressed immunohistochemically by all the atypically proliferating tumors. Vimentin was also detected in six of the original tumors but only in one primary culture. The capacity to culture and study cells which represent possible intermediate stages in the evolution of ovarian malignancy may prove useful as an in vitro model for this disease.