Bilateral teratoma of testis in two brothers with 47,XXY Klinefelter's syndrome

Two brothers, the only children of healthy, unrelated parents with normal karyotypes, had 47,XXY-Klinefelter's syndrome and bilateral testicular teratomas. The oldest XXY-boy had, in addition, congenital hydrocephalus caused by congenital stenosis of the aqueduct of Sylvius.