[Klinefelter's disease and leydigiomas. A report of one case (author's transl)].

The authors present the case of a patient with Klinefelter syndrome who, at the age of 36 years, developed a multifocal Leydig cell tumour of the right testicle, presenting as hematuria. After orchidectomy, the patient developed an identical tumour in the remaining testes. This curious case of a patient in whom the clinical and laboratory features of Klinefelterer's syndrome, were masked by the Leydig cell tumour and vice versa, is analyzed. Study of this case, and a review of the literature of the three cases published in the past, offer no definitive solution to the problem of the possible link between the Leydig cell tumour and the Klinefelter syndrome, but a prospective study protocol is suggested with such an aim in mind. More careful clinical and laboratory evaluation of populations of Klinefelter's syndrome and Leydig cell tumours should provide a solution. More routine therapy of Klinefelt syndrome should possibly avoid the development of complications in the form of testicular Leydig cell tumours by causing inhibition of useless and excessive pituitary actions by the administration of androgens immediately after puberty.