[Immature teratoma of the testis associated with Klinefelter's syndrome: a case report]

A case of testicular immature teratoma associated with Klinefelter's syndrome is reported. The patient was a 6-month-old boy and admitted with the chief complaint of painless mass in the left scrotum. Left high orchiectomy was performed and the pathological diagnosis was immature teratoma of the left testis. He was also diagnosed with Klinefelter's syndrome because chromosome analysis of the tumor tissue and peripheral blood leukocyte revealed 47, XXY, but the only congenital anomaly was overfolded helix. We discuss the association between the testicular tumor and Klinefelter's syndrome.