![]() ![]() International groups have suggested criteria for action after automated CBC and WBC differential analysis. 5 Regardless of the instrument used, a flagged blood sample triggers action before the CBC and WBC differential can be released most commonly, this is a review of a peripheral blood (PB) smear. Spurious elevations of the WBC count can also be seen, including platelet clumps, nucleated RBCs, incomplete lysis of RBCs, cryoglobulins, and cryofibrinogen. Whereas these smaller instruments may work well for screening a normal, healthy population, the presence of abnormal cells may cause error flags and inaccurate counts, resulting in a high review rate when used in a hospital-based population. The automated hematology analyzers used in laboratories within physicians' offices may use older methodologies for cell analysis, such as impedance technology, which generates a 3-part leukocyte differential that includes lymphoid cells/basophils, neutrophils/eosinophils, and monocytes/other mononuclear cells. 4 Based on proprietary algorithms, hematology analyzers will flag high or low numbers of specific cell types and possibly abnormal populations of leukocytes, including immature granulocytes, blasts, and variant/atypical lymphocytes. Nucleated RBCs are also detected routinely, and some analyzers also quantitate immature granulocytes. 3 The newer generation of hematology analyzers can examine thousands of leukocytes using flow cytometry–based methodology, some in combination with cytochemistry or fluorescence or conductivity, to elucidate different types of WBCs, including neutrophils, lymphocytes, monocytes, basophils, and eosinophils (ie, the 5-part differential). Other causes of reactive myeloid leukocytoses are also discussed herein.Īutomated hematology analyzers rapidly analyze whole blood samples for the complete blood cell count and differential, including WBC count, RBC count, platelet count, hemoglobin concentration, hematocrit, RBC indices, and the leukocyte differential. Myeloid leukemoid reactions commonly result from infections and show activated neutrophil changes on morphology these should prompt evaluation for infection. ![]() Confirmation and characterization of myeloid malignancies should be performed with a BM examination and the appropriate ancillary studies. The manual differential is key, along with correct enumeration of blasts and blast equivalents, immature granulocytes, basophils, and eosinophils and identifying dysplasia to identify myeloid malignancies. Myeloid leukocytosis triggers a differential diagnosis of myeloid leukemoid reactions versus myeloid malignancies. Samples suspicious for lymphoproliferative disorders can be confirmed and characterized by flow cytometry, with molecular studies initiated in select cases precursor lymphoid neoplasms (lymphoblasts) should trigger a BM examination. Distinguishing a reactive lymphoid proliferation from a lymphoproliferative disorder requires examination of lymphocyte morphology for pleomorphic lymphocytes versus a monomorphic population, with the latter favoring a lymphoproliferative neoplasm. Next is separation of the leukocytosis into a myeloid versus a lymphoid process. Examination of the PB smear is essential to confirming the automated blood cell differential or affirming the manual differential performed on the PB smear. Confirmation of the complete blood cell count and the WBC differential is the first step. Distinguishing malignant from benign leukocytosis is a critical step in the care of a patient, which initiates a vastly different decision tree. Leukocytosis, or elevated WBC count, is a commonly encountered laboratory finding. ![]()
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