A nurse is assisting in the care of an adolescent client who has been diagnosed with testicular cancer. The nurse understands that testicular cancer most often develops from mutations of which of the following types of cells?

A. Leukocytes. Leukocytes (white blood cells) are involved in the immune response and are not the primary cells affected in testicular cancer. Cancers of leukocytes include leukemia and lymphoma, not testicular cancer. B. Germ cells. This is correct. Testicular cancer most commonly arises from germ cells, which are the cells responsible for producing sperm. Germ cell tumors (GCTs) account for over 90% of testicular cancers, including seminomas and non-seminomas. C. Epithelial cells. Epithelial cells line various tissues and organs, but they are not the primary source of testicular cancer. Epithelial cell cancers, like carcinomas, more commonly affect the skin, lungs, and digestive tract. D. Lymphocytes. Lymphocytes are a type of white blood cell involved in the immune system. Testicular lymphoma can occur but is rare compared to germ cell tumors, which are the most frequent type of testicular cancer in adolescents and young adults.