A single classification of the common epithelial, germ cell, sex cord, and stromal tumors is adopted by the World Health Organisation (WHO) and the International Federation of Gynecology and Obstetrics (FIGO).

These are the three type of cells found inside the ovaries:

Epithelial cells

Epithelial cells are linked to epithelial cell tumors and found on the outer surface of the ovary.

Germ cells

Ovarian germ cells are known to be the surface cells of the adult ovary that represent the germline. These are also known as competent embryonic stem cells. Ovarian germ cells are linked to ovarian germ cell tumors and are also known as competent embryonic stem cells. . These are surface cells that represent the germ line of the adult ovary.

Stroma cells

Stroma cells look similar to fibroblasts. These spindle-shaped cells are distributed in such a way that it appears whorled. They secrete estrogen and are associated with maturing follicles that exhibit endocrine function.

Other than these, there are some circumstances where malignant or cancerous tumors can develop inside the ovaries and spread to other nearby organs or tissue areas.

Epithelial ovarian tumors

Epithelial ovarian cancers emerge from the epithelium covering the ovary. There are four main subtypes of epithelial tumors:

  • serous
  • endometrioid
  • mucinous
  • clear cell.

Borderline epithelial tumors

These are less aggressive tumors that were previously known as low-potential malignant tumors. Since these tumors do not grow into supporting tissues of the ovaries; these tumors are known to be different from the usual types of ovarian cancer tumors.

Malignant germ cell tumors

Malignant germ cell tumors arise from primitive germ cells in the embryonic gonad and are more common in young women. These include:

  1. Teratomas: Teratomas contain one or more of three germ layers cells:

endoderm ( the innermost layer)

mesoderm ( the middle layer)

ectoderm (the outermost layer).

Non-cancerous or benign germ cell tumors are called mature teratoma and the cancerous forms are called immature teratoma.

2. Dysgerminoma: The common type of germ cell tumor is Dysgerminoma that usually affects women in their twenties. The treatment includes surgery followed by adjuvant therapy in the form of chemotherapy or radiation.

3. Endodermal sinus tumor and choriocarcinoma: Choriocarcinoma is a very rare tumor that usually originates in the placenta during pregnancy. It grows and spreads rapidly and is more common than the type of cancer that originates inside the ovary.

4. Ovarian stromal tumors: Ovarian stromal tumors develop in women of age 50 and above but in a few rare cases, they can also occur in young girls. It is caused when a lot of estrogen is produced by the body. The most common symptoms of these kinds of tumors are seen to be abnormal vaginal bleeding.