Rarity of IgH translocations in Waldenström macroglobulinemia.

Comparatively little is known of the cytogenetics of Waldenström macroglobulinemia (WM). This is primarily due to the low proliferation of the clonal B cells, which precludes conventional karyotyping in many cases. Translocations involving the immunoglobulin heavy chain (IGH) gene at 14q32 are characteristic of many B-cell lymphomas and myelomas. Initial reports suggested that the t(9;14) was characteristic of lymphoplasmacytic lymphoma (the underlying pathological diagnosis in WM), but subsequent studies have failed to confirm the uniqueness of the translocation. To clarify this, we examined 69 cases of WM with interphase fluorescence in situ hybridization and failed to demonstrate an IgH translocation in 67 (97%). We conclude that IGH translocations are not a feature of WM, and the implications of this finding are discussed.