Background: Gene rearrangements and specific translocations define some B-cell non-Hodgkin lymphoma (NHL) subtypes. Genome-wide mutational studies have revealed recurrent point mutations with prognostic implications. The goals of this study were to evaluate the feasibility of applying a multiplex mutation assay to archival cytospin preparations (CPs) and to investigate the rate of EZH2, CD79B, and MYD88 mutations in B-cell NHL samples previously tested for MYC rearrangement and/or IGH/BCL-2 translocation.
Methods: DNA was extracted from archival CPs of B-cell NHL cases with previous fluorescence in situ hybridization (FISH) assays for MYC rearrangement and/or IGH/BCL-2 translocation. Multiplex sequencing was performed for the detection of EZH2 (Y641), CD79B (Y196), and MYD88 (L265) mutations. Sanger sequencing was applied to samples with positive results and failed assays.
Results: Eighty-eight archival CPs were available from 40 patients. Alterations detected by FISH were: MYC rearrangement (10 cases), IGH/BCL-2 translocations (21 cases), dual translocations (6 cases), and other abnormalities for IGH/BCL-2 (23 cases) and for MYC (16 cases). DNA concentration ranged from 1.88 to 62.85 ng/µL (mean, 9.46 ng/µL). Successful results were obtained in 88.0% of the specimens submitted to multiplex sequencing. With Sanger sequencing, 2 additional mutated cases were found, and all cases with mutations were confirmed. Eight specimens showed mutations: 6 for EZH2, 1 for CD79B, and 1 for MYD88. Among them, 5 cases showed concurrent MYC and/or IGH/BCL-2 translocations and 2 revealed abnormal signals of IGH/BCL-2 and MYC.
Conclusions: CPs archived for up to 6 years are a reliable source of high-quality genomic material for multiplex sequencing. Almost all B-cell NHL with point mutations showed concurrent chromosomal abnormalities.
Keywords: B-cell non-Hodgkin lymphoma; CD79B; DNA mutational analysis; EZH2; IGH/BCL2; MYC; MYD88; MassARRAY spectrometry; cytospin preparation; fine needle biopsy.
© 2015 American Cancer Society.