Figure 1
Strategy for PCR-based clonality diagnostics in suspected lymphoproliferations with an inconclusive diagnosis or with unusual histology, immunophenotype or clinical presentation, using the EuroClonality/BIOMED-2 multiplex PCR protocols. In case of a suspected B-cell proliferation, IGH VH–JH multiplex PCR analysis is best performed first. As a second step, IGK PCR analysis (Vκ–Jκ and Kde rearrangements) can be chosen. Preferably, these two steps are combined to avoid delay in the diagnostic process. Finally, IGH DH1-6–JH PCR analysis (potentially combined with IGL analyses) can be reserved for remaining suspected cases, in which the preceding PCR assays have failed to detect monoclonality and have not shown clear signs of polyclonality either. For suspected T-cell proliferations, TCRB multiplex PCR is generally slightly more informative than TCRG PCR, but the order of analysis of these two loci can be changed as they provide complementary information; preferably both targets should be used in parallel. Only in case of suspected TCRγδ+ T-cell proliferations and immature T-cell proliferations (suspicion of lymphoblastic malignancies), combined TCRG and TCRD PCR analysis is preferred. In case of suspected lymphoproliferations of unknown origin, both Ig and TCR genes should be used as PCR targets. It should be noted that in such cases the clonal Ig/TCR results cannot be used straightforwardly for B-/T-lineage assignment. A full-proof diagnosis of polyclonality remains difficult, but a high probability of polyclonality is supported by clear Gaussian GS curves or HD smears in the absence of clonal results.
