ABSTRACT
Ovarian epithelial carcinomas are the most common lethal gynecological malignancies. Ovarian carcinomas are divid-ed into Types I and II based on different morphologies, genetic alterations, and biomarker expression. Low-grade micropapillary serous carcinoma are Type I tumors. Type I tumors are slow growing, generally confined to the ovary at diagnosis, and with better prognosis. These tumors develop from well established precursor lesions that are termedborderlinetumors. Type 1 tumors are genetically stable and are characterized by mutations in a number of different genes including KRAS, BRAF, PTEN, and beta-catenin. Type II tumors are rapidly growing and highly aggressive neoplasms, for which well defined precursor lesions have not been described. They may arise in the fimbrial epithelium of the oviduct with advanced stage, more aggressive behavior, and worse prognosis. High-grade serous carcino-ma belongs to Type II tumors. This group of tumors has a high level of genetic instability and is characterized by TP53 mutation. Hence, ovarian cancer comprises a heterogeneous group of tumors with distinctly different histological characteristics, molecular genet-ic features, and clinical course.