Lymphocyte subsets in bone marrow lymphoid nodules and malignant lymphoma nodular involvement

The lymphocyte subsets in 67 cases of bone marrow benign or reactive lymphoid nodules (LN) and 23 cases of nodular involvement by B malignant lymphoma (B-ML) have been immunohistochemically characterized on paraffin embedded trephine biopsies utilizing a panel of 10 monoclonal antibodies. LCA was positive in 90% LN and B-ML lymphocytes; LN2, MB2 stained more than 50% LN and B-ML lymphocytes; MT2 stained more than 50% LN and less than 50% B-ML lymphocytes; UCHL1 stained the 20% of LN lymphocytes; LN1 stained only B cells of the rare germinal centers; MT1 only myeloid cells, L26 only plasma cells. DF-T1 and Leu 22 failed to stain LN or B-ML lymphocytes. While anti-T lymphocyte antibodies reacted inconstantly with lymphoid cells in decalcified and embedded specimens, LCA and some anti-B lymphocyte antibodies gave constantly reproducible results for bone marrow LN and B-ML. They permitted an easy recognition and exact evaluation of the size of LN, the identification of scattered B cells, the detection of the residual or minimal involvement by B-ML and the exact burden of the invasion, but could not allow a convincing differential diagnosis between LN and small cell B-ML nodular involvement.