Germ cell tumors are rare and around two-thirds of them are considered to be benign. It is estimated that around 2 to 4 percent of the tumors that develop from the primordial germ cells are cancers in children and individuals younger than 20 years of age. Germ cells are those that develop in the embryo and become the cells of the reproductive system. These cells follow the midline path through the body that develops and descends into the pelvis as the ovarian cells or testicular cells. It is considered that most of the tumors of the ovaries and the testes have their origin in the germ cells. The tumors that occur outside the reproductive sites are known as extragonadal sites and can be found in the chest, the head, abdomen, pelvis and the lower back areas. Germs cells can also spread and invade other parts of the body. The common sites the germ cells tumors can invade include the lungs, liver, lymph nodes, central nervous system and rarely the bone marrow or other organs. The germ cell tumors are based on the type of cells involved and some of the common types of germ cell tumors include; Teratomas, germinomas, Endodermal sinus tumor, choriocarcinoma and embryonal carcinoma.
Teratomas
Teratomas are the common germ cells tumor detected in the ovaries. The ovarian teratomas are rare and are considered to affect girls and women up to their early 20s. There are two types of ovarian teratoma; mature teratoma which is non-cancerous and immature teratoma that are cancerous. The mature teratoma is often diagnosed among women in their reproductive years and can be surgically removed. The immature teratomas are rare and are cancer cells that occur at a very early stage of development. Most of the immature teratomas can be cured even in an advanced stage.
Germinomas
These are the malignant germ cell tumors which are known as dysgerminoma when identified in the ovaries and are called seminomas when they occur in the testes. Around 15% of all germ cell tumors in children represent germinomas. Dysgerminomas is the most frequently occurring malignant ovarian germ cell tumors affecting the children and adolescents.
Choriocarcinoma
This is a type of cancer that occurs when the cells that were a part of the pregnancy becomes cancerous. It can occur after a full term pregnancy, an abortion or a miscarriage. This is a very rare form of malignant cancer that develops from the cells in the chorion. These cells can also form a tumor in the placental cells during pregnancy and spread to affect the infant. The gestational choriocarcinoma commonly occurs in pregnant females between the ages of 15 and 19 and non-gestational choriocarcinoma is the term used when a non-pregnant young child develops this condition from the cells originating from the placenta that is in the body.
Embryonal carcinoma
These are malignant cells that are normally mixed with other forms of germ cell tumors that commonly occur in the testes. When these cells mix with the benign type of tumor, the embryonal carcinoma can cause it to become malignant.
References
http://www.cancerresearchuk.org/about-cancer/ovarian-cancer/types/teratoma
http://www.embryology.ch/anglais/ugenital/patholgenital07.html
https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=90&contentid=p02725
