It is known that CD3 and CD20 are homogenously expressed in T lineage and B lineage lymphoma, respectively; however, there are no standard guidelines to interpret immunohistochemistry findings. In this study, we investigated CD3 and CD20 immunohistochemical staining patterns of bone marrow (BM)-infiltrating lymphoma cells.Methods.
Among 297 patients diagnosed with malignant lymphoma, the BM biopsy slides of all 39 cases found to have BM infiltration (T lineage: 11; B lineage: 28) were reviewed. We specifically investigated the immunohistochemical staining patterns of CD3 and CD20.Results.
All 11 T lineage lymphoma cases showed homogenous immunohistochemical staining patterns. In the 28 B lineage lymphoma cases, 15 (53.6%) showed a homogenous pattern while 13 (46.4%) showed a heterogeneous pattern. Ten cases in the latter group showed additional evidence of BM infiltration by lymphoma cells in separate laboratory analyses or imaging studies. There were no differences in overall or progression-free survival rates in patients exhibiting homogeneous vs. heterogeneous staining patterns (P=0.81 and P=0.59, respectively).Conclusions.
A considerable number of B lineage cases showed heterogeneous patterns with evidence of BM infiltration. Thus, heterogeneous immunohistochemical staining patterns (particularly in B lineage lymphomas) may signify malignant lymphoma cell infiltration into the BM.