Ovarian borderline tumors, sometimes called low malignant potential (LMP) ovarian tumors, have some benign and some malignant features. LMP tumors make up approximately 10%-15% of all ovarian tumors. They develop earlier than epithelial ovarian cancer, around the age of 40–49. They typically do not have extensive invasion; 10% of LMP tumors have areas of stromal microinvasion (<3mm, <5% of tumor). LMP tumors have other abnormal features, including increased mitosis, changes in cell size or nucleus size, abnormal nuclei, cell stratification, and small projections on cells (papillary projections). Serous and/or mucinous characteristics can be seen on histological examination, and serous histology makes up the overwhelming majority of advanced LMP tumors. More than 80% of LMP tumors are Stage I; 15% are stage II and III and less than 5% are stage IV. Implants of LMP tumors are often non-invasive.