Diagnosis of unexpected acute myeloid leukemia and chronic lymphocytic leukemia: A case report demonstrating the perils of restricted panels in flow cytometric immunophenotyping

We report on the flow cytometric identification of concomitant acute myeloi d leukemia and chronic lymphocytic leukemia in cytology specimens submitted with minimal clinical information. A 64-year-old man presented with fever and progressive dyspnea on exertion. Chest X-ray and computed tomography sc an showed a left upper lobe pulmonary mass. Pulmonary capillary pullback sp ecimens were collected to determine infectious verses neoplastic etiology. The pulmonary capillary pullback specimens showed atypical mononuclear cell s with enlarged, slightly irregular nuclei; visible nucleoli; and basophili c cytoplasm. Flow cytometric analysis of the specimen for lymphoma was requ ested. Flow cytometric immunophenotypic studies showed that 78% of the cell s were CD34 positive, CD45 dim positive and CD11c positive, consistent with acute myeloid leukemia. About 0.75% of the cells expressed CD5 as well as dim CD20 and were monoclonal for kappa light chains: consistent with chroni c lymphocytic leukemia/small lymphocytic lymphoma. At this time the clinici an communicated a history of myelodysplastic syndrome of refractory anemia subtype. Peripheral blood was obtained for further immunophenotyping and th e patient was immediately treated for his acute myeloid leukemia. This case demonstrates that a diagnostic antibody panel should allow evaluation of a ll cell types as per the U.S./Canadian consensus recommendations on the imm unophenotypic analysis of hematologic neoplasia by flow cytometry (Stewart et al.: Cytometry 30:231-235, 1997). Cytometry (Comm. Clin. Cytometry) 42:1 14-117, 2000. Published 2000 Wiley-Liss, Inc.