Hematologic malignancies and Klinefelter syndrome: a chance association?

Klinefelter syndrome was first described in 1942 as an endocrine disorder characterized by gynecomastia, hypogonadism, small testes, and elevated levels of follicle-stimulating hormone. An extra X chromosome (i.e., 47,XXY) was subsequently demonstrated in these patients and an increased incidence of leukemia and lymphoma has been described. We report a retrospective study of a series of unselected patients with Klinefelter syndrome diagnosed by cytogenetic studies and the occurrence of hematologic malignancies. The literature is also reviewed.