A primary or metastatic malignant neoplasm that affects the testis. Representative examples include seminoma, embryonal carcinoma, sarcoma, leukemia, and lymphoma. The disease is Monarch Disease Ontology id MONDO_0005447 (testicular cancer). Also known as: cancer of testis, malignant neoplasm of testis, malignant neoplasm of the testis, malignant testicular neoplasm, malignant testicular tumor, malignant testicular tumour, malignant testis neoplasm, malignant tumor of testis.