Low-grade intestinal lymphoma of intraepithelial T lymphocytes with concomitant enteropathy-associated T cell lymphoma: case report suggesting a possible histogenetic relationship.

In a low-grade small cell intestinal lymphoma found in a 41-year-old woman with celiac disease, the neoplastic intraepithelial lymphocytes (IELs) showed cytoplasmic granules, expressed the alpha/beta T cell antigen receptor (TCR), and stained positively for the IEL antibody, HML-1. The tumor cells carried the CD3 and CD7 T cell antigens, but were double negative for CD4 and CD8 and also lacked other T cell antigens (CD1, CD2, and CD5). Tumor cell monoclonality was proven by the demonstration of a rearranged TCR-beta chain gene. The special marker profile of the lymphoma may be explained by partial antigenic deletion of the phenotype which characterizes the majority of normal IELs (TCR alpha/beta+, CD3+, CD8+, or CD4+). Alternately, the tumorous cell clone might originate from an as yet unrecognized TCR alpha/beta+, CD3+, CD7+, CD4-, CD8- normal subset of IEL. In the presented case, a concomitant high-grade large cell lymphoma supports the assumption that enteropathy-associated T cell lymphomas (EATCLs) derive from the intestinal IEL population and suggests that EATCLs may be preceded by a low-grade IEL lymphoma.