DIAGNOSIS OF GASTROINTESTINAL T-CELL LYMPHOMAS IN ROUTINELY PROCESSEDTISSUES

Diagnosis of primary gastrointestinal T-cell lymphomas is often proble matic because lymphoma may not be suspected clinically or on resection , and tissue may not be frozen for immunophenotyping. Furthermore, ulc eration and inflammation and the polymorphous character of the lesions makes evaluation difficult. Only approximately 150 cases have been re ported, fewer than 20 from North America. We have tried to establish a reliable approach to the diagnosis of gastrointestinal lymphomas of T -cell phenotype in routinely processed tissue. Sections from five prim ary gastrointestinal T-cell lymphomas were stained with a panel of 13 antibodies reactive in routinely fixed, paraffin-embedded tissue. Thes e included antibodies to pan-T- and pan-B-cell antigens (CD3, CD20), B - and T-cell-associated antigens (CD43, CD45R0; CDw75, CD74), antigens expressed by activated T-cells (HLA-DR, CD30), leukocyte antigens (CD 45, CD15), and macrophage markers (MAC-387, HAM-56). All stained posit ively with T-cell markers MT-1 and Leu-22, four with UCHL-1, and three with anti-CD3 polyclonal antibody. B-cell markers identified by L-26 and LN-1 were negative in all five, whereas LN-2 was expressed in two. Two expressed HLA-DR; all were Ber-H2 negative. Two had an abnormal p henotype: one was Leu-M1 positive, and one LCA negative. Ten B-cell ga strointestinal lymphoma controls were negative for MT-1, Leu-22, and C D3, and nine were negative for UCHL-1. Nine were positive for the B-ce ll marker L-26, eight for LN-2, and seven for LN-1. All tumors were ne gative for monocyte-macrophage markers. This antibody panel provides a reliable means for identifying gastrointestinal T-cell lymphomas in p araffin sections. Use of a panel is advisable because of variation in expression and preservation of antigens, and to detect abnormal phenot ypes. Application of this approach may facilitate the diagnosis of gas trointestinal T-cell lymphomas both prospectively and in archival mate rial, and thereby encourage studies of the behavior and treatment of t hese neoplasms.