Combined cytogenetic testing and fluorescence in situ hybridization analysis in the study of chronic lymphocytic leukemia and multiple myeloma

We investigated the usefulness of fluorescence in situ hybridization (FISH) panels when testing for chromosomal aberrations of known prognostic significance in chronic lymphocytic leukemia (CLL) and multiple myeloma (MM). Our CLL panel included probes for 11q, 12 centromere, 13q, 14, and 17p. Karyotype and FISH were abnormal in 13 of 60 (21.6%) cases, two (3.3%) abnormal by karyotype alone, and 25 (41.6%) by FISH alone. Karyotype and FISH were normal in 16 (27%) patients, and 4 samples were unsuitable for karyotype analysis. One patient had an abnormality not included in the panel (20q deletion). FISH was abnormal in 19 cases (31.6%) with a normal karyotype and in 6 cases with no analyzable metaphases. Thirteen CLL cases with abnormal karyotypes were either confirmed or clarified by FISH. The MM panel probes were 11q, 13q, 17p, and t(11;14). Karyotype and FISH were abnormal in 18 of 139 (13%) MM cases. Twenty patients (14.4%) had a normal karyotype and abnormal FISH. Two samples not suitable for metaphase analysis were abnormal by interphase FISH. Karyotype and FISH were normal in 94 (68%) patients. Five patients (3.6%) had chromosomal abnormalities not included in the panel. Compared to karyotyping alone, the FISH panels improved the detection rate of recurrent chromosomal aberrations in CLL from 22-63% and in MM from 15-29%.