The current proposal is a pilot study. The Investigators plan to use next generation genome sequencing (NGGS) to define the molecular and genetic profiles of 3 cases of germ cell tumor (GCT) (with a component of yolk sac tumor) at the time of the initial diagnosis and 3 cases of late relapse GCT's, which are characterized by yolk sac tumor (and AFP secreting) predominant disease.

Investigators seek to demonstrate the feasibility of obtaining tissue biopsies (either archived or new biopsy) and utilization of NGGS in studying the molecular and genetic relationships between GCT's (with a component of yolk sac tumor) at the time of diagnosis and GCT's at the time of late relapse. This study will also provide preliminary information on genetic alterations, which may be a hypothesis for generating another study.

This study will examine two cohorts:

1. The initial diagnosis only cohort will include 3 patients with GCT who meet the inclusion criteria and have adequate tissue samples available in storage at the Pathology Department. One prospective blood and one tissue sample will be collected from each patient in this cohort. Tissue samples will come from the orchiectomy or virgin retro-peritoneal lymph node dissection (RPLND) that was done at initial diagnosis.
2. The late relapse cohort will include 3 patients with late relapse GCT who meet the inclusion criteria and have adequate tissue samples available in storage at the Pathology Department. One prospective blood and two tissue samples will be collected from each patient in this cohort. Tissue samples will come from the orchiectomy or virgin RPLND that was done at initial diagnosis and the other will come from the site of late relapse.

Patients in this cohort will have biopsies at the site of late relapse as part of their routine cancer treatment. No biopsies will be performed specifically for the purposes of this study. Tissue from the site of late relapse will also be requested from the Pathology Department.

One tube of blood will be collected from each subject during a routine clinical visit at baseline when a blood draw is already being done.

In summary, a total of 15 samples will be evaluated on this study. Consent for the use of tissue and blood collected for the purposes of this study will be obtained prior to any study procedures. Subjects who do not have adequate tissue samples available will be replaced.

Eligible patients will have:

1. Germ cell tumor (GCT) (with a component of yolk sac tumor) at the time of the initial diagnosis or a late relapsed GCT (for the purposes of this study, late relapse will be defined as relapse > 2 years from the initial treatment of GCT).
2. Adequate tumor specimens available from the initial orchiectomy specimen or virgin retro-peritoneal lymph node dissection (RPLND).
3. Adequate tumor specimens available from any site of recurrent disease for patients accrued in the "late relapse" cohort.
4. Tumor specimens collected prior to start of chemotherapy in the "late relapse" cohort.
5. Age > 18 years
6. Willing to provide informed consent

Patients with germ cell tumor (GCT) (with a component of yolk sac tumor) at the time of the initial diagnosis or a late relapsed GCT.