Frequency of clonal intraepithelial T lymphocyte proliferations in enteropathy-type intestinal T cell lymphoma, coeliac disease, and refractory sprue

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Abstract
BACKGROUND Clonal T cell receptor (TCR) gene rearrangements and loss of T cell antigens such as CD8 and TCR-β in intraepithelial lymphocytes (IELs) may indicate the development of an enteropathy-type intestinal T cell lymphoma (EITCL) in patients with refractory sprue. AIMS To define the diagnostic value of these markers in duodenal biopsies from patients with villous atrophy as a result of various underlying disorders. PATIENTS AND METHODS Duodenal biopsies from eight patients with coeliac disease and five patients with villous atrophy caused by defined disorders were compared with three patients with refractory sprue evolving into overt EITCL, two patients with ulcerative jejunitis, and with eight patients with overt EITCL, for expression of CD3, CD4, CD8, and TCR-β in IELs using immunohistochemistry and for clonal TCR-γ gene rearrangements using polymerase chain reaction. In addition, biopsies from six consecutive patients with refractory sprue of uncertain cause were examined. RESULTS Clonal TCR-γ gene rearrangements were found in all resected tumours of patients with EITCL, in 3/8 duodenal biopsies of patients with EITCL, in 2/2 patients with ulcerative jejunitis, in 2/3 patients with refractory sprue evolving into overt EITCL, and in 1/6 patients with refractory sprue. No rearrangements were found in biopsies from patients with refractory sprue caused by defined disorders or those with coeliac disease. Clonality in duodenal biopsies was associated with an abnormal phenotype of IELs in all cases and in all but one case in patients with evidence of underlying coeliac disease. Specificity for detection of an EITCL using immunohistology was 77% for CD8 and for TCR-β staining, and 100% for detection of a clonal TCR-γ gene rearrangement. Sensitivity was 62% for staining with CD8 and clonality investigation, while sensitivity reached 100% for TCR-β staining in all investigated patients with EITCL. CONCLUSIONS Clonal proliferations of phenotypically abnormal IELs in refractory sprue represent an early manifestation of EITCL, for which the term “sprue-like intestinal T cell lymphoma” is proposed. This constellation is also found in duodenal biopsies from patients with an overt EITCL and is not related to other sprue syndromes, resulting in a high specificity for detection of an EITCL or refractory sprue evolving into EITCL. Overt EITCL may develop directly from coeliac disease without a precursor lesion (refractory sprue with clonal IELs) being demonstrable in duodenal biopsies or via a “sprue-like intestinal T cell lymphoma”. This latter entity is a complication of coeliac disease.