Hi, Eric. We are so sorry you have to go through this, but you are welcome here. Hopefully we can help you navigate the complexities. We know this can be overwhelming.
Is the abdominal tumor the origin, or was a tumor found in one of your testicals? If the abdominal was the origin, then this is called an extra-gonadal germ cell tumor. These are as treatable as if they resulted from spread fron a testical tumor. The oncologist will probably recommend chemo or possibly radiation. It is usually very wise to get a second opinion, preferably from a center of excellence such as Indiana University, Sloane Kettering, Dana-Farber, etc.
Were blood tests done to check for tumor markers, i.e., chemicals released by some of the types of TC cancers? What were the results?
Get copies of all reports for future reference. It's a pretty good idea to bring someone with you to all appointments and take lots of notes to make sure you catch ever speck of info. Ask lots of questions.
Some of our members here have had extra-gonadal seminomas and hopefully they will be along shortly with additional advice.
Best of luck. You will be in our prayers.