Discrepant immunophenotypic characteristics between the lymph node and bone marrow in two mixed-phenotype acute leukemia patients

The immunophenotypic profile of hematological malignancies is usually consistent among different sites of involvement; this consistency allows reliable diagnosis from peripheral blood, bone marrow, or lymph node, especially in cases of acute leukemia. Although in a minority of lymphoma patients, two or more different populations with discordant immunophenotypes have been described, either at the same or distinct sites. Here, we report two Korean patients with acute leukemia where the results of immunophenotypic analysis of the bone marrow specimen were different from those of immunohistochemical studies of a biopsy sample of a cervical lymph node, particularly with respect to myeloperoxidase and CD3. The clinical significance of the immunophenotypic disparity found in the patients still remains unknown; however, discrepancies between the different anatomic sites that are simultaneously involved can occur in a subset of leukemia patients. Therefore, integration of all the relevant results, including those of the bone marrow studies, may be helpful for accurate diagnosis and selecting appropriate treatment modalities.