ClearLLab 10C Case Book

Results of Flow Cytometric Immunophenotyping

Flow cytometric immunophenotyping identifies a phenotypically distinct population of progenitors with expression of intermediate CD5, variable CD7, intermediate CD13, intermediate CD33, bright CD34, intermediate CD38, dim CD45, intermediate CD117, dim CD123 and bright HLA-DR without CD14, CD15, CD64 and other lymphoid or myeloid antigens. Compared with normal CD34-positive progenitors, the expression of CD5 and CD7, increased CD34, and decreased expression of CD45 is aberrant. In addition, the monocytes (green) show aberrant expression of CD56 and granulocytes (blue) show abnormally decreased side scatter suggesting hypogranularity with aberrant expression of increased CD11b and increased CD33. The immunophenotype of the abnormal progenitor population is that of mildly expanded abnormal CD34-positive progenitors. This finding along with abnormalities of monocytes and granulocytes in the context of an elderly patient with cytopenias is consistent with a myeloid stem cell disorder, in particular a low-grade myelodysplastic syndrome. However, a diagnosis of myelodysplasia requires morphologic and cytogenetic correlation, including a morphologic blast count to exclude acute myeloid leukemia. Additional testing shows the presence of 14% blasts by morphology with 22% monocytes and a normal karyotype which raises the possibility of chronic myelomonocytic leukemia (CMML), but additional laboratory correlation is required for definitive classification.

Table of Contents > Neoplastic Process of Myeloid Origin > Case #24: Myelodysplastic Syndrome

Every Event Matters

585 Beckman Coulter • ClearLLab 10C Panels • C30134 AA