Aggressive jejunal lymphoma of large granular lymphocytes. Immunohistochemical, ultrastructural, molecular, and DNA content analysis.

An unusual large cell lymphoma of the proximal jejunum with large granular lymphocyte (LGL) morphologic characteristics and T-helper/inducer cell phenotype is described. Although the cells strongly expressed Leu-7 (HNK-1), studies with antibodies directed against the more specific natural killer (NK) antigens, CD16 (Leu-11) and Leu-19, were negative. Ultrastructural analysis of the neoplastic cells demonstrated substantial numbers of electron-dense granules and rare parallel tubular arrays. Clonal rearrangement of the T-cell receptor beta chain gene and germline configuration of the immunoglobulin heavy chain gene confirmed the T-cell origin of the neoplastic cells. This lymphoma pursued an aggressive clinical course, with rapid dissemination to the lungs and central nervous system. DNA content analysis indicated that a similar DNA aneuploid population was present in the jejunal primary and lung tissue at recurrence. There was no evidence of nodal, peripheral blood, splenic, or bone marrow involvement. Morphologic and functional similarities between the lymphoid tissues of the gastrointestinal tract and lung have previously prompted a classification of the immune system into distinct peripheral somatic and mucosal components. Based on the distribution and migratory properties of the tumor cells in this case, the authors propose that this lymphoma arose from a minor mucosa-associated LGL subset that may be unrelated to circulating LGLs. In addition, these observations emphasize that prominent granulated cytomorphologic features may be seen in neoplastic disorders with the T-helper/inducer phenotype, as well as in the more widely recognized lymphoproliferative disorders of NK and cytotoxic/suppressor cell types.