Detection of chromosome abnormalities using cytoplasmic immunoglobulin staining and FISH in myeloma

The low proliferation rate of myeloma cells in vitro can result in a normal cytogenetic karyotype with the abnormal cell population not being detected. Because plasma cell myeloma is a patchy disease, conventional FISH is also hampered by normal cell contamination. Identification of plasma cells by cytoplasmic immunoglobulin staining in combination with FISH (cIg FISH) can ensure that only the cells of interest are analyzed, and thus the results obtained are a more accurate reflection of the plasma cell population karyotype. Current literature suggests that probes for t(4;14), t(14;16), and del(17)(p13) should be used in routine diagnostic testing; however, this technique can be used for any probes of interest. In this chapter, we present the techniques and methods used in our laboratory for the detection of abnormalities in plasma cells by cIg staining in conjunction with FISH.