Resolution of platelet count interference due to cytoplasmic fragments of leukaemic cells by flow cytometry in acute myeloid leukaemia.

BACKGROUND

Platelet count interference could lead to problems in clinical decisions especially in the cases of thrombocytopenia. Here we report a case of platelet count interference in Beckman Coulter DxH800 haematology analyser due to cytoplasmic fragments of leukaemic cells in acute myeloid leukaemia. A 19-year-old female patient presented to the emergency department with bruises and anaemic symptoms. A machine platelet count (by impedance method) was 40 × 109 /L. There was a flag on platelet count interference by debris. Peripheral blood smear showed some bluish cytoplasmic fragments are seen mimicking platelets.

METHOD: Immunological platelet counting by flow cytometry using fluorochrome-labeled antibodies against platelet markers CD41 and CD61 was attempted by adopting and modifying from the ICSH reference method for platelet counting. Events with low forward scatter and positive CD41 and/or CD61 expression were identified as platelets, and events with high forward scatter and negative CD41 and CD61 expression were identified as red cells.

RESULTS

The platelet count was derived from the formula: Platelet count = RBC count (Haematology analyser) × PLT event (flow cytometry)/RBC events (flow cytometry). The immunological platelet count was determined to be 2 × 109 /L, which is much lower than the original machine count and platelet transfusion was warranted.