Benign and Low Grade Serous Epithelial Tumors: Recent Developments and Diagnostic Problems

This review focuses on recent advances in the area of low-grade ovarian serous neoplasia with emphasis on key diagnostic criteria, differential diagnosis, and disease classification based on current understanding of low-grade serous carcinogenesis. Despite considerable controversy surrounding serous tumors of low malignant potential (S-LMP) or borderline tumors, there have been great strides in our understanding of the serous group of borderline and malignant pelvic epithelial neoplasms in the past decade. Most S-LMP have a favorable prognosis, but recurrences and progression to carcinoma occur, sometimes following a protracted clinical course. Pathologic risk factors vary, but the extraovarian implant status is the most important predictor for progressive disease. Progression of S-LMP usually takes the form of low-grade serous carcinoma, although transformation to high-grade carcinoma is occasionally seen. A pelvic S-LMP - low-grade serous carcinoma pathway has been proposed based on global gene expression profiling, shared mutations in KRAS and/or BRAF, and in most cases, the presence of S-LMP in de novo low-grade serous carcinoma. Unlike high-grade serous carcinoma, low-grade serous carcinoma responds poorly to standard platinum-based chemotherapy. Development of more tailored therapy for S-LMP with invasive implants and low-grade serous carcinoma, ideally based on a relative risk model for disease progression, is under active clinical investigation.