Detecting Clonal T-Cell Populations in Refractory Celiac Sprue and Cutaneous T-Cell Lymphoma: A Comparison of Two TCR Gamma Gene Rearrangement PCR Assays
M Wagner, X Zhu, A Carlin, M Kilgore, S Burkholder, L Houk, AJ Dimarino, J Lee, J Palazzo, T Edmonston. Thomas Jefferson University, Philadelphia, PA
Background: The detection of clonal T-cell populations in tissue specimens has important diagnostic and prognostic implications for a variety of diseases. In patients with refractory celiac sprue (RCS), the presence of a clonal T-cell population in the small bowel portends a high risk of progression to enteropathy-associated T-cell lymphoma. Detecting a clonal T-cell population in the skin may allow for a more definitive diagnosis of cutaneous T-cell lymphoma (CTCL). We compared the clinical sensitivities of two TCR gamma gene rearrangement (TCR) assays (BIOMED-2 assay and Gene Rearrangement (GR) assay, InVivoScribe) in biopsies of patients with clinically and histologically confirmed RCS and CTCL as well as controls.
Design: DNA was extracted from formalin-fixed, paraffin-embedded tissue sections from 20 skin biopsies and 11 duodenal biopsies. The skin biopsies comprised 9 cases of CTCL, 4 pseudolymphomas (PL), 2 B-cell lymphomas (BCL), and 5 indeterminate cases (IND). The duodenal biopsies comprised 4 cases of RCS, 5 cases of uncomplicated celiac sprue (UCS), and 2 cases of T-cell lymphoma. TCR analysis was then performed using both the BIOMED-2 and the GR assays in duplicate using different amounts of template DNA.
Results: The GR assay detected clonality in 9 skin biopsies (6/9 cases of CTCL, 0/4 PL, 0/2 BCL, and 3/5 IND) and 4 duodenal biopsies (2/4 cases of RCS, 0/5 UCS, and 2/2 cases of T-cell lymphoma). The BIOMED-2 assay detected clonality in 10 skin biopsies (6/9 cases of CTCL, 1/4 PL, 0/2 BCL, and 3/5 IND) and 5 duodenal biopsies (3/4 cases of RCS, 0/5 UCS, and 2/2 cases of T-cell lymphoma). Discrepancies were noted in 3 skin biopsies and 1 duodenal biopsy. 2 CTCLs were positive with one assay but not the other, 1 PL was false positive with the BIOMED-2 assay, and 1 RCS was positive with the BIOMED-2 but not the GR assay.
Conclusions: In this study, the BIOMED-2 assay detected more clonal TCR gamma gene rearrangements than the GR assay in both the skin biopsies and the duodenal biopsies. Given the equivalent clinical sensitivity of both assays for CTCL, the GR assay may be preferable if TCR analysis is needed due to fewer false positive results. The BIOMED-2 assay appears to have a higher clinical sensitivity for RCS than the GR assay and thus may be the preferred assay for these patients due to the prognostic implications.
Tuesday, March 10, 2009 11:30 AM
Platform Session: Section G2, Tuesday Morning