GRANZYME B-EXPRESSING PERIPHERAL T-CELL LYMPHOMAS - NEOPLASTIC EQUIVALENTS OF ACTIVATED CYTOTOXIC T-CELLS WITH PREFERENCE FOR MUCOSA-ASSOCIATED LYMPHOID-TISSUE LOCALIZATION

T-cell non-Hodgkin's lymphomas can be considered the neoplastic equiva lents of immunologically functional, site-restricted T lymphocytes. Li ttle is known about the occurrence and clinical behavior of T-cell lym phomas that are the neoplastic equivalents of different functional T-c ell subsets. Here. we investigated the prevalence. preferential site, immunophenotype, and clinical behavior of the neoplastic equivalents o f activated cytotoxic T cells (CTLs) in a group of 140 nodal and extra nodal T-cell lymphomas. Activated CTLs were shown immunohistochemicall y with a monoclonal antibody against granzyme B, a major constituent o f the cytotoxic granules of activated T cells. Granzyme B-positive T-c ell lymphomas were mainly found in mucosa-associated lymphoid tissue ( MALT; nose, 63% of the cases; gastrointestinal tract, 46%; and lung, 3 3%). Granzyme B-positive cases with primary localization in MALT were more often associated with angioinvasion (P = .005), necrosis (P = .00 2), and histologic characteristics of celiac disease in adjacent mucos a not involved with lymphoma. Eosinophilia was more often observed in granzyme B-negative cases (P = .03). Most cases belonged to the pleomo rphic medium- and large-cell group of the Kiel classification. CD30 ex pression was more often found in granzyme B-positive lymphomas of MALT (P = .04), whereas CD56 expression was exclusively found in nasal gra nzyme B-positive lymphomas. Immuno-phenotypically, most of the cases s hould be considered as neoplastic equivalents of activated CTLs based on the presence of T-cell markers on tumor eels. In two cases of nasal lymphoma, tumor cells probably were the neoplastic counterparts of na tural killer cells. The prognosis of the granzyme B-positive gastroint estinal T-cell lymphomas was poor but did not differ from granzyme B-n egative gastrointestinal T-cell lymphomas. This indicates that, in per ipheral T-cell lymphomas, site of origin is more important as a progno stic parameter than derivation of activated CTLs. (C) 1994 by The Amer ican Society of Hematology.