Figure 2
The dualistic pathways in developing low-grade and high-grade “ovarian” serous carcinoma. The Type I pathway develops from the presumed fallopian tube epithelial stem cells that disseminated into the ovulation site where those stem cells form surface inclusion cysts. Those cysts may continue to grow into serous cystadenomas and clonally develop into serous borderline tumors, which represent the precursor lesions of low-grade serous carcinomas. In contrast to the step-wise tumor progression pathway as observed in Type I serous tumors, in the Type 2 pathway, many high-grade serous carcinomas arise as a result of dissemination of their precursor lesions, serous tubal intraepithelial carcinomas (STICs), in the fallopian tube fimbriated ends.