Chronic myelogenous leukemia and Klinefelter's syndrome

Chronic myeloid leukemia in case of Klinefelter syndrome

Klinefelter syndrome (KS) is a sex chromosome disorder and has been reported to be associated with increased risk for malignancies. We report a 22-year-old male patient who was diagnosed to have chronic myeloid leukemia in chronic phase. Bone marrow cytogenetic examination revealed karyotype 47, XXY, t (9; 22)(q34, q11) suggestive of KS with presence of Philadelphia chromosome. The patient was treated with oral imatinib mesylate (400 mg/day). Complete hematological response was achieved after 2 months of therapy. The bcr-abl/abl transcript percentage measured from peripheral blood at baseline, 1 and 2 years after imatinib were 97%, 1.99%, 0.007%, respectively. He remains in complete hematological and major molecular remission after 2 years of continued imatinib therapy.

Constitutional chromosome aberrations as pathogenetic events in hematologic malignancies

A predisposition to tumor development is associated with some constitutional chromosomal abnormalities. Investigations of families with an apparent hereditary cancer and constitutional chromosome rearrangements have led to the molecular identification of tumor suppressor genes. Under the somatic mutation theory for the development of cancer, two mutational events are required. The first step may be a constitutional event and the second an acquired genetic mutation. Cytogenetic studies were performed on 5633 bone marrow specimens from patients with hematologic malignancies from a single institution. Fifty cases of constitutional chromosome aberrations were detected. Data collected from the literature and from our series are reviewed and compared with the incidence of specific constitutional chromosome aberrations in the newborn population. Possible mechanisms that may predispose individuals with constitutional chromosome aberrations to the development of a hematologic malignancy are reviewed.

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.

Trisomy 8 in myelodysplasia and acute leukemia is constitutional in 15-20% of cases

The trisomy 8 found in malignancies may derive from a constitutional trisomy 8 mosaicism (CT8M), and in these cases the trisomy itself may be regarded as the first mutation in a multistep carcinogenetic process. To assess the frequency of CT8M in hematological dysplastic and neoplastic disorders with trisomy 8, an informative sample of 14 patients was collected. The data ascertained included chromosome analyses of fibroblast cultures and of PHA-stimulated blood cultures in patients with normal blood differential count, as well as possible CT8M clinical signs. One patient showed trisomy 8 in all cell types analyzed and undoubtedly has a CT8M; a second patient consistently showed trisomy 8 in PHA-stimulated blood cultures when no immature myeloid cells were present in blood and should be considered as having CT8M; a third patient, with Philadelphia-positive chronic myelocytic leukemia, was more difficult to interpret, but the possibility that she had CT8M is likely. A few clinical signs of CT8M were also present in these three patients. Our data indicate that the frequency of CT8M in hematological dysplastic and neoplastic disorders with trisomy 8 is approximately 15-20%.

Cancer incidence in men with Klinefelter syndrome

Many case reports have suggested an association between Klinefelter syndrome (KS) and cancer, but studies of the cancer incidence in larger groups of men with KS are lacking. A cohort of 696 men with KS was established from the Danish Cytogenetic Register. Information on the cancer incidence in the cohort was obtained from the Danish Cancer Registry and compared with the expected number calculated from the age, period and site specific cancer rates for Danish men. A total of 39 neoplasms were diagnosed (relative risk = 1.1). Four mediastinal tumours were observed (relative risk = 67); all four were malignant germ cell tumours. No cases of breast cancer or testis cancer were observed. One case of prostate cancer occurred within a previously irradiated field. No excess of leukaemia or lymphoma was found. An increased risk of cancer occurred in the age group 15-30 years (relative risk = 2.7). All six tumours in this group were germ cell tumours or sarcomas. The overall cancer incidence is not increased and no routine cancer screening seems to be justified. A considerably elevated risk of mediastinal germ cell tumours occurs in the period from early adolescence until the age of 30.