Agnogenic myeloid metaplasia associated with Klinefelter syndrome: a case report.

Klinefelter syndrome is the most commonly diagnosed sex chromosome disorder among males. It is usually associated with 47 chromosomes, including two Xs and one Y. The formal cytogenetic designation for Klinefelter syndrome is 47, XXY; the extra sex chromosome is due to meiotic chromosomal nondisjunction. Increased risk of various malignant diseases has been recognized among patients with different congenital chromosomal abnormalities. Since the early 1960s, numerous reports have appeared of an increased risk of malignant neoplasms among patients with Klinefelter syndrome. Evidence suggests a correlation with increased incidences of germ cell tumors and breast cancers. Whether these patients are at an increased risk of hematologic malignant disease, especially acute leukemia, is still uncertain. This report describes a patient with agnogenic myeloid metaplasia and Klinefelter syndrome, an association not previously reported.