Final answer:
The most appropriate test for staging in a 28-year-old male who has had an orchiectomy for a mixed germ cell tumor is a CT scan.
Step-by-step explanation:
The most appropriate test for staging in a 28-year-old male who has had an orchiectomy for a mixed germ cell tumor is a CT scan. A CT scan, or computed tomography scan, is a diagnostic imaging test that uses a combination of X-rays and a computer to create detailed cross-sectional images of the body. It can help determine whether the cancer has spread beyond the testis, providing important information for staging and treatment planning.