Evaluation of T-cell Clonality in Archival Skin Biopsy Samples of Cutaneous T-cell Lymphomas Using the Biomed-2 PCR Protocol

Recently, several European centers of lymphoma diagnosis and research developed various polymerase chain reaction (PCR) methods for clonality analysis in suspect T-cell and B-cell proliferations (Biomed-2 Concerted Action). They have mainly been applied to frozen material of systemic B-cell and T-cell malignancies. Thus far, only limited data exist with regard to cutaneous T-cell lymphoma (CTCL) and paraffin-embedded material. Thus, we applied the Biomed-2 T-cell receptor (TCR) gamma and TCR beta PCR as well as an in-house TCR gamma PCR to a collection of 107 archival skin samples (84 CTCL, 3 systemic TCL and 20 controls). As a result, the Biomed-2 TCR gamma PCR revealed 81% clonality, the in-house TCR gamma method revealed 86% clonality, and the Biomed-2 TCR beta revealed 78% clonality in CTCL samples generating at least the 300 bp fragment in the Biomed-2 control PCR. We found clonal TCR beta rearrangements in 5 of 17 CTCL samples that were polyclonal in the Biomed-2 TCR gamma PCR. By combining all Biomed-2 assays, one or more clonal rearrangements were detected in 87% of CTCL and in all 3 systemic TCLs. By combining all TCR PCR assays applied here, clonality was shown in 90% of the CTCL cases. In conclusion, we showed that the Biomed-2 TCR PCR worked well with DNA from paraffin-embedded tissue, revealing a high-clonality detection rate in CTCL, and thus should be highly recommended for routine molecular analysis. In addition, the performance of our in-house TCR gamma assay verifies our previously published findings on clonally expanded T-cells in CTCL.