Clonal chromosome abnormalities in patients with Waldenström's and CLL-associated macroglobulinemia: significance of trisomy 12.

We performed cytogenetic analyses by Q- and G-banding techniques of unstimulated or B-mitogen-stimulated spleen, bone marrow, and peripheral blood cells from six patients with malignant macroglobulinemia [two with Waldenström's macroglobulinemia (WM) and four with chronic lymphocytic leukemia associated macroglobulinemia (CLL-M)]. Normal karyotypes were obtained in two of the treated patients (one with WM in remission and the other with CLL-M in relapse). An extra chromosome 12 (trisomy 12) was observed in all four untreated patients. In patient no. 2 (K.R.) and no. 3 (F.G.) with CLL-M, an abnormal karyotype, with trisomy 12 as the only abnormality, was identified. In patient no. 1 (C.C.) with WM, there were two clonal chromosome changes, identified: 47, XX, -9, +12, plus marker chromosome and 48, XX, -9, +12, plus both marker and minute chromosomes. In patient no. 4 (R.M.) with CLL-M, a minute chromosome with or without loss of a G-group chromosome was seen in some metaphases without trisomy 12, in addition to metaphases with trisomy 12 alone. Each of the four untreated patients with WM or CLL-M had clonal chromosome abnormalities, suggesting that chromosome changes may be more frequently associated with WM or CLL-M than with typical CLL without macroglobulinemia. These observations also suggest that trisomy 12 may be the primary karyotypic change in malignant macroglobulinemia, whereas the appearance of the minute or marker chromosome as well as the loss of G-group chromosomes or chromosome no. 9 may be secondary karyotypic changes resulting from clonal evolution in these malignancies.