[Testicular germ cell tumor arising in the male with a chromosomal abnormality of 45,X/46,X,del(Y)].

A 25-year-old-man came to our outpatient clinic complaining of swelling of the left scrotal contents. He had a past history of 3 surgeries for hypospadia. His left testis was stony hard and testicular tumor was suspected. High orchiectomy was performed under general anesthesia. The pathological diagnosis was mixed type testicular germ cell tumor. Chromosomal analysis revealed a karyotype of 45,X/46,X,del(Y). Most of the long arm of the Y chromosome was missing. Prophylactic chemotherapy was performed. Treatment options for genetically high risk patients of testicular malignancies were discussed.