Aims The BIOMED-2 multiplex PCR protocol is a commonly used procedure for assessing B cell clonality in lymphoma diagnostics. Follicular lymphoma poses a special challenge for PCR-based analyses because of high prevalence of somatic hypermutations in the rearranged immunoglobulin (IG) domains. This study aimed to evaluate the BIOMED-2 protocol performance in detection of B cell clonality in follicular lymphoma using formalin-fixed, paraffin-embedded (FFPE) tissue.
Methods FFPE samples from 118 patients diagnosed with follicular lymphoma in the period 1998–2008 were used in the study. Clonality of IG heavy (IGH) and light chains (IGK, IGL) was assessed using a PCR procedure that was optimised for FFPE tissue.
Results The highest clonal detection rates were 67.8% with the IGH Vн-FR2-Jн assay and 66.1% with the IGK Vκ-Jκ assay. Clonality was detected in 94.9% of all FFPE follicular lymphoma samples when all assays were combined. FFPE samples stored for 1–5 years did not perform significantly differently from those stored for 6–11 years. Interobserver agreement of clonality was tested for all analyses. The lowest score (Cohen’s κ value = 0.56) was observed for the IGK Vκ-Jκ clonality assay.
Conclusions An improved PCR protocol for detection of clonality in FFPE samples using BIOMED-2 IG primers is presented. For best performance, a combination of IGH and IGK analyses is recommended.
- follicular lymphoma
- immunoglobulin rearrangements
- molecular pathology
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Funding The study was funded by a grant provided by Helse Vest, Haukeland University Hospital.
Competing interests None to declare.
Provenance and peer review Not commissioned; externally peer reviewed.