Insertion of the CCND1 gene into the IgH locus in a case of leukaemic small cell mantle lymphoma with normal chromosomes 11 and 14

Derivative (14)t(11;14)(q13;q32)t(11;14)(p11.2;p11.2): a novel unbalanced variant of the t(11;14)(q13;q32) translocation in mantle cell lymphoma

We report the case of a 62-year-old man who presented with splenomegaly, leukocytosis, anemia, and thrombocytopenia. Examination of the peripheral blood, bone marrow, and spleen revealed involvement by mantle cell lymphoma, with some blastoid features and an atypical phenotype. Spleen and bone marrow classical chromosome analysis followed by fluorescence in situ hybridization revealed a novel and unusual unbalanced variant of the t(11;14)(q13;q32) translocation, resulting in a complex derivative chromosome harboring the IGH/CCND1 fusion gene. This chromosome was designated as der(14)t(11;14)(q13;q32)t(11;14)(p11.1;p11.2).

Molecular cytogenetic analysis of leukemic mantle cell lymphoma with a cryptic t(11;14)

We report a case of leukemic mantle cell lymphoma of the blastoid variant with complex chromosomal rearrangements leading to the recombination of BCL1 from 11q13 and IGH from 14q32. G-banding analysis showed, in addition to multiple other chromosome abnormalities, a del(11)(q13) and addition of unknown material to chromosome arms 13p and 21p. The two latter rearrangements were revealed, by use of multicolor in situ hybridization (M-FISH) analysis, to be a der(13)(qter-->p11::14q32::11q13-->11q22::14q32-->14q11::11q22-->11qter) and a similar der(21)(qter-->p11::14q32::11q13-->11q23::14q32-->14q11::11q22-->11qter). FISH with locus-specific probes for BCL1 and IGH showed a fusion signal on both derivative chromosomes.

Cytogenetics of lymphomas

Cytogenetic analysis is now a routine part of the diagnosis and management of a significant number of lymphoid malignancies. Whilst conventional cytogenetics remains the most comprehensive method for assessing chromosome abnormalities, the technical difficulties associated with conventional cytogenetics in most lymphomas has resulted in increased use of fluorescence in situ hybridisation (FISH) to identify specific abnormalities that are useful in either the diagnosis or management of these disorders. The finding of one of the Burkitt's translocations is of major importance in the diagnosis of Burkitt's and Burkitt's-like lymphomas, whereas the t(14;18), although seen in most follicular lymphomas (FL), is not usually required to make a diagnosis. Thus, whilst cytogenetics may be of interest in FL, it is not an essential part of the diagnostic work-up. Conventional cytogenetics may be useful for identifying markers of resistance to Helicobacter pylori therapy in MALT lymphomas. In disorders such as Hodgkin lymphoma, hairy cell leukaemia and lymphoplasmacytoid lymphoma, although many cytogenetic abnormalities have been observed, no consistent or specific abnormalities have been identified and so, at this point in our knowledge of the genetics of these disorders, cytogenetics cannot be considered a useful test for either diagnosis or prognosis. In contrast, the diagnosis of mantle cell lymphoma is now dependent upon the identification of the 11;14 translocation that results in cyclin D1 up-regulation. It is widely acknowledged that FISH is the most consistently useful test to identify the juxtaposition of the CCND1 and IGH genes in mantle cell lymphoma and is regarded as the 'gold standard'. FISH also has a role in identifying genetic abnormalities of prognostic significance in chronic lymphocytic leukaemia. Given the wealth of genetic and cytogenetic abnormalities that are continuing to be found in chronic lymphoid malignancies, it will be some time before the optimal use of both conventional cytogenetics and FISH is established in the diagnosis and management of lymphomas.