FISH diagnostics in plasma cell myeloma: recommendations and own experience

Abstract

Plasma cell myeloma (PCM) is disease with heterogeneous clinical outcomes. It is increasingly evident that the genetic features of the tumor cells largely dictate the clinical heterogeneity of PCM. Primary chromosomal alterations in myeloma can be divided into hyperdiploid and non-hyperdiploid subtypes. Secondary chromosomal changes occur during progression of disease. Cytogenetic abnormalities are important prognostic markers in PCM and some of them were incorporated into the current prognostic staging system of PCM. The presence of t(4;14), t(14;16), t(14;20), gain of 1q or TP53 deletion is considered to be high-risk myeloma. Detection of these alterations can be performed by interphase fluorescence in situ hybridization (FISH) after separation or identification of the plasma cells. The proper FISH examination in myeloma has to meet further requirements regarding aspirating and timing of samples, probe selection and their cut-off levels, the criteria of accurate analysis and reporting. Based on the literature, we here present technical recommendations regarding FISH in PCM. Furthermore, we share our own experience in FISH diagnostics acquired over 12 years. In this period, we have performed nearly 2,050 FISH tests in 603 myeloma patients and used two different methods of myeloma FISH: FISH on immunolabeled plasma cells, and target FISH with the BioView system.