Sexual precocity in Klinefelter syndrome: report on two new cases with idiopathic central precocious puberty.

Precocious puberty apparently occurs more often in boys with Klinefelter syndrome than could be expected by chance. So far, reports exist on nine such patients, to which two more cases are added here. Whereas most of the previously described boys had endocrinologically active tumours, these two patients had sexual precocity of the idiopathic type.