With sex cord-stromal ovarian cancer, Ovarian refers to “ovary”, of which women have two that sit along either side of the uterus. The term sex cord refers to an embryonic structures that develop into ovarian follicles and stromal cells are the connective tissue of any organ. So a sex cord-stromal ovarian cancer is a type of tumor that develops from either ovarian follicle cells or connective tissue cells.
Each ovary has multiple follicles. Each follicle is made up of an oocyte, which is an immature egg, surrounded by two types of cells - theca cells and granulosa cells. Granulosa and theca cells work together to support follicle development. Luteinizing hormone stimulates theca cells to generate androgens and follicle stimulating hormone stimulates granulosa cells to convert those androgens to estradiol using the enzyme aromatase. A large increase in estradiol triggers ovulation.
During ovulation, the oocyte pops out of the ovary, causing a bit of damage to the surface. Fibrocytes detect that damage and differentiate into fibroblasts and lay down collagen to help repair the damage.
If any of those cells starts to divide uncontrollably, it can either form a benign tumor which means that it doesn’t invade nearby tissue or spread to other parts of the body, or it can be a malignant tumor which means that it can invade nearby tissue and spread to other parts of the body. Compared with benign tumor cells, malignant tumor cells have key features like not having a clearly defined border or like having slightly less organized nuclei.
The first main type of sex-cord stromal tumor is a granulosa-theca cell tumor. And these are the most common malignant stromal tumors and they’re associated with middle-aged women. These tumors often end up producing way too much estradiol, and this can cause very specific hormone associated symptoms like uterine bleeding, breast tenderness, and early puberty in young girls. Under the microscope, these tumors classically develop little fluid pockets scattered throughout the tissue that are called Call-Exner bodies.
The second type of tumors, fibromas, are made of fibroblasts and are benign tumors. Under the microscope, they look like thin needle-like strands with elongated nuclei that are bundled together. Benign fibromas are often seen in combination with ascites, a fluid buildup in the peritoneal cavity, as well as pleural effusion, a fluid buildup in the pleural cavity.
In fact, the clinical triad of a benign ovarian tumor with ascites and a pleural effusion, is better known as Meigs syndrome. The exact pathogenesis here, though, is unclear, but it’s thought that the solid ovarian tumor irritates the peritoneal and pleural surfaces which leads to a transudative fluid buildup in both spaces. Fibromas can occasionally grow to the size of an orange and can cause a pulling sensation in the groin when it compresses the round ligament of the uterus.