Abstract
Cytogenetic analysis including multicolor spectral karyotyping (SKY) and interphase fluorescence in situ hybridization (FISH) was performed on 154 consecutive cases with suspected lymphoma. The cytogenetic results were reviewed in correlation with the final pathologic diagnosis. A diagnosis of lymphoma was established in 94 cases, with 16 Hodgkin lymphomas and 78 non-Hodgkin lymphomas (NHL). Cytogenetic results were obtained in 63 NHLs (81%); 61 of those showed abnormal karyotypes (97%). The t(14;18) or IGH-BCL2 fusion was detected in 83% (20/24) of follicular lymphomas and in 57% (12/21) of diffuse large B-cell lymphomas (DLBCL). The application of interphase FISH and SKY has contributed to a high detection rate of t(14;18) in DLBCLs. This study showed that genes at 1q25, 3p21, 3q21, 5q31, 6p23, 7q22, 8q11 approximately q12, 9q34, 11q23, 12q13, and 19q13.1 may have been involved as the less common changes in follicular lymphoma and DLBCL. Comparison of the recurrent secondary aberrations in the groups of follicular lymphoma and DLBCL revealed a pattern of clonal evolution from the changes rea(1)(p36), del(6q), +7, +12 or dup or trp(12)(q13q22), +der(18)t(14;18), and +21 in follicular lymphoma to the changes rea(1)(p36), del(6q), +6, +7, +9, rea(11)(q23), +12, -13 or del(13(q12q14), +18, +21, and +X in DLBCL. The clonal evolution of the secondary aberrations is thought to contribute to the progression of the disease. About 90% (16/18) of other types of NHL had abnormal karyotypes showing specific translocations or gene rearrangements consistent with the pathologic diagnosis. A comprehensive cytogenetics approach including SKY and interphase FISH using probes for specific genes, such as IGH, BCL2, CCND1, and ALK, is a very useful ancillary diagnostic tool for lymphomas. The combined approach also led to the identification of t(2;19)(p23;q13.1) as a new variant of t(2;5)(p23;q35) in a case of Ki-1-positive anaplastic large cell lymphoma with a null cell phenotype.
