Comparison between Conventional Cytogenetics and Interphase Fluorescence in situ Hybridization (FISH) for Patients with Multiple Myeloma

A retrospective analysis of cytogenetic alterations in patients with newly diagnosed multiple myeloma: a single center study in Korea

Background

The accurate identification of cytogenetic abnormalities in multiple myeloma (MM) has become more important over recent years for the development of new diagnostic and prognostic markers. In this study, we retrospectively analyzed the cytogenetic aberrations in MM cases as an initial assessment in a single institute.

Methods

We reviewed the cytogenetic results from 222 patients who were newly diagnosed with MM between January 2000 and December 2015. Chromosomal analysis was performed on cultured bone marrow samples by standard G-banding technique. At least 20 metaphase cells were analyzed for karyotyping.

Results

Clonal chromosome abnormalities were detected in 45.0% (100/222) of the patients. Among these results, 80 cases (80.0%) had both numerical and structural chromosome abnormalities. Overall hyperdiploidy with structural cytogenetic aberrations was the most common finding (44.0%), followed by hypodiploidy with structural aberrations (28.0%). Amplification of the long arm of chromosome 1 and -13/del(13q) were the most frequent recurrent abnormalities, and were detected in 50 patients (50.0%) and 40 patients (40.0%) with clonal abnormalities, respectively. The most common abnormality involving 14q32 was t(11;14)(q13;q32), which was observed in 19 cases.

Conclusion

These findings demonstrate that myeloma cells exhibit complex aberrations regardless of ploidy, even from a single center in Korea. Conventional cytogenetic analysis should be included in the initial diagnostic work-up for patients suspected of having MM.

Variant Burkitt-type translocation (8;22)(q24;q11) in plasma cell myeloma

Variant Burkitt-type translocation, t(8;22)(q24;q11), is very rare in plasma cell myeloma. We report a 51-year-old male patient with plasma cell myeloma, who showed t(8;22) (q24;q11). He suffered from pelvic pain for two months, and showed IgG, lambda type of monoclonal gammopathy (5.14 g/dL; 49.9% of protein). His bone marrow examination showed increased plasma cells (66.9% of all nucleated cells). Plasma cells (74.9% of all nucleated cells) and monoclonal spike (3.38 g/dL; 42.2%) persisted after three cycles of thalidomide and dexamethasone. Cytogenetic analysis showed complex chromosomal abnormalities: 44,XY,-1,t(2;5)(q33;q13),add(8)(q24.1),t(8;22)(q24.1;q11.2),add(10) (p15), der(11)t(1;11)(q21;p11.2),del(12)(p11.2p13),-13,-14,add(14)(q32),der(15)t(1;15)(p2 2;p11.2),-16,add(17)(q11.2),+21,+1-3mar[cp6]/46,XY[19]. To the best of our knowledge, this is the first report on plasma cell myeloma with a variant Burkitt-type t(8;22)(q24;q11) in the Korean patient. A review of 11 such cases in the literature, including the present case, implicated that plasma cell myeloma with t(8;22)(q24;q11) might be related to advanced stage and poor prognosis.