Description

Sample A was from a 49 year old male patient previously diagnosed with acute monocytic leukemia. The patient was initially treated with combination chemotherapy with good response, but now presented in a first relapse.

The WBC was moderately increased and was accompanied by a mild anemia and thrombocytopenia. The WBC differential showed monocytosis (19.5 x 10^9/L), half of which were classified as blast cells. The complete WBC differential was nevertheless marked with asterisks because the algorithm was unable to make a clear separation between mononuclear and polymorphonuclear cells. This issue was clearly visible in the 90 º/WBC 10 º scatterplot and resulted in the flag DFLT (NLMEB). Visual interpretation of the WBC scatterplots suggested that the default threshold lines spuriously classified a part of the “monocyte” population as basophil and neutrophil. This finding was confirmed by manual microscopy where the majority of the cells were classified as immature blast cells, displaying monocytoid features. The URI warning flag signifies that there was a possible interference in the platelet count. Most likely this interference was due to cell fragments or plasma components and were visible in the 0 º/RBC 10 º scatterplot as black dots.

Three days after the collection of sample A, sample B was taken and noticeable is that the WBC count decreased to 19.2 x 10^9/L and that the DFLT (NLMEB) flag has disappeared. Interpretation of the 90º/WBC 10º scatterplot clearly demonstrated a much better separation than the same graph of case A. Despite the less problematic separation between mononuclear and polymorphonuclear cells, the algorithm still had difficulties differentiating mononuclear cells into monocytes, lymphocytes and basophils. The problematic separation of mononuclear cells resulted in a DFLT (LM) flag.