Discordant immunophenotype of chronic B-cell lymphoproliferative disorders in simultaneous specimens from bone marrow and peripheral sites.

This study consisted of 10 cases of chronic B-cell lymphoproliferative disorders that had simultaneous specimens obtained from both bone marrow and peripheral sites for flow cytometric immunophenotyping. The immunophenotyping results of peripheral sites from all 10 cases showed a monoclonal B-cell proliferation expressing monoclonal surface immunoglobulin, CD19, CD20, HLA-DR, and CD5 (except 1 case). Eight (80%) of the 10 cases, however, demonstrated discordant immunophenotypes with myeloid-associated marker expression (CD13, CD11b, and/or CD15) found only in the bone marrow. Patients with CD13 or CD11b marker expression in the bone marrow followed an aggressive clinical course with advanced Rai's stage and a diffuse or mixed bone marrow infiltration pattern or disease transformation. These results indicate that discordant immunophenotypes of malignant cells from different body sites occur in chronic B-cell lymphoproliferative disorders and are not uncommon. Additionally; myeloid-associated markers, which some investigators have described as being associated with an unfavorable clinical course, may be expressed only in bone marrow specimens in these disorders. Thus, bone marrow specimens may be preferential in determining myeloid-associated marker expression in chronic B-cell lymphoproliferative disorders.