HIGH-INCIDENCE OF MONOSOMY-18 IN LYMPHOID MALIGNANCIES THAT HAVE BONE-MARROW AND PERIPHERAL-BLOOD INVOLVEMENT

We studied the incidence of numerical chromosome 18 abnormalities in 1 07 patients with lymphoid malignancies by fluorescence in situ hybridi zation (FISH) using a directly conjugated centromeric probe for chromo some 18. Samples were obtained by fine needle aspiration of diseased n odes, bone marrows or peripheral blood. Monosomy 18 was more common in chronic lymphocytic leukemia (43%), small lymphocytic lymphoma (28%), and follicular lymphomas (12.5%) than in diffuse lymphomas (5.3%; p < 0.01). Monosomy 18 was detected in 9.7-17.1% of the cells in non-Hodg kin's lymphoma (NHL) (background, 5.4%; 99% CI, 4.2%-6.6%) and in 8%-1 6.7% (median, 10%) of the cells in (CLL) (background, 3.4%; 99% CI, 2. 5%-4.3%). All patients with monosomy 18 were found to have bone marrow involvement. Of all untreated patients who had disease involving the bone marrow, 32% were found to have monosomy 18. Trisomy 18 was detect ed in 3.6%-48.2% of the cells in NHL (background, 0.9%; 99% CI, 0.2%-1 .6%) and was most common in diffuse large-cell lymphoma (34%) and foll icular lymphomas (31%). None of the patients with small lymphocytic ly mphoma or chronic lymphocytic leukemia had trisomy 18. There wars no c orrelation between trisomy 18 and response to treatment or clinical pr esentation. In this study, monosomy 18 was observed frequently in pati ents with lymphoid malignancies that involve the bone marrow and perip heral blood. Our data suggest that important gene(s) located on chromo some 18 may be involved in homing of the malignant lymphocytes to the bone marrow and peripheral blood.