Leydig cell tumor of the testis in Klinefelter syndrome: MR detection.

Klinefelter syndrome is associated with the development of breast and extragonadal germ cell tumors in some patients. Leydig cell tumor in association with Klinefelter syndrome is a rare entity. We report such a case to illustrate the usefulness of MR imaging in detecting a testicular neoplasm when clinical examination and ultrasonography are equivocal.