Serous borderline ovarian tumor and low-grade serous ovarian cancer

Epithelial ovarian cancer (EOC) is the most frequent histological subtype of ovarian cancer, accounting for 95% of ovarian cancer. Radiologists are familiar with the imaging appearances of high-grade serous ovarian cancer (HGSOC) that accounts for about 70% of EOC. Low grade serous ovarian cancer (LGSOC) represents 2-5% of ovarian carcinomas and 5-10% of serous ovarian carcinoma. Historically, it was thought that LGSOC and HGSOC were a continuum. It is now clear that these are two completely separate entities. They have different molecular biology and clinical course. As a result of the low prevalence of LGSOC, there is limited data on its imaging findings. In this paper, we illustrate the pathology, molecular biology and treatment options of LGSOC. We present imaging appearances of LGSOC of primary tumor and metastasis in a cohort of 33 patients with pathologically-proven LGSOC. We also elucidate the differences between LGSOC and HGSOC. Since LGSOC often arise from serous borderline ovarian tumors (SBOT), we describe the imaging appearances of SBOT and highlight the differences between these two entities.