A comparison between monoclonal antibody MT2 and immunoglobulin staining in the differential diagnosis of follicular lymphoid proliferations in routinely fixed wax-embedded biopsies.

Monoclonal antibody MT2 and anti-immunoglobulins were tested for their ability to discriminate between reactive lymphoid hyperplasia and follicular lymphoma (centroblastic/centrocytic; CB/CC) informalin-fixed and wax-embedded biopsies. The streptavidin biotin peroxidase complex method was used. In 46 of 49 cases of reactive follicular hyperplasia the follicle center cells were unstained by MT2 whereas the mantle zone B cells and interfollicular T cells were positive. In three reactive cases up to 30% of follicle center cells also were stained. In contrast, more than 50% of neoplastic follicle center cells were stained by MT2 in 27 of 62 cases of CB/CC, and light chain restriction was shown in 52 of 62 cases. MT2 staining and/or light chain restriction was seen in 57 of 62 cases. In 106 further cases of non-Hodgkin's lymphoma, MT2 was positive in 59 of 77 B cell lymphomas and 3 of 29 T cell lymphomas. Although not a B cell specific reagent, MT2 is useful in the differential diagnosis of reactive vs. neoplastic follicular lymphoid proliferations but is less sensitive than immunoglobulin stains.