Extragonadal germ cell tumors form from developing sperm or egg cells that travel from the gonads to other parts of the body.
"Extragonadal" means outside of the gonads (sex organs). When cells that are meant to form sperm in the testicles or eggs in the ovaries travel to other parts of the body, they may grow into extragonadal germ cell tumors. These tumors may begin to grow anywhere in the body but usually begin in organs such as the pineal gland in the brain, in the mediastinum, or in the abdomen.
There are several types of plasma cell neoplasms. These diseases are all associated with a monoclonal (or myeloma) protein (M protein). They include monoclonal gammopathy of undetermined significance (MGUS), isolated plasmacytoma of the bone, extramedullary plasmacytoma, and multiple myeloma.
(Refer to the Lymphoplasmacytic Lymphoma (Waldenström Macroglobulinemia) section in the PDQ summary on Adult Non-Hodgkin Lymphoma Treatment for more information.)
Incidence and Mortality
Extragonadal germ cell tumors can be benign (noncancer) or malignant (cancer). Benign extragonadal germ cell tumors are called benign teratomas. These are more common than malignant extragonadal germ cell tumors and often are very large.
Malignant extragonadal germ cell tumors are divided into two types, nonseminoma and seminoma. Nonseminomas tend to grow and spread more quickly than seminomas. They usually are large and cause symptoms. If untreated, malignant extragonadal germ cell tumors may spread to the lungs, lymph nodes, bones, liver, or other parts of the body.
For information about germ cell tumors in the ovaries and testicles, see the following PDQ summaries:
Age and gender can affect the risk of extragonadal germ cell tumors.
Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Risk factors for malignant extragonadal germ cell tumors include the following:
Malignant extragonadal germ cell tumors may cause symptoms as they grow into nearby areas. Other conditions may cause the same symptoms. Check with your doctor if you have any of the following problems: