Description

This patient presented with leukocytosis, due to absolute (53.1 x 10^3/μL) and relative (93.1%) lymphocytosis. The VAR LYM and BLAST flags were triggered, and as a result, the lymphocyte, monocyte and basophil counts were suspect. RBC and PLT counts as well as red cell indices were within normal ranges.

Scatterplots showed a dominant and elongated lymphocyte cluster (cyan) on the IAS vs ALL scatterplot, and the presence of a significant sub-population of lymphocytes that were smaller in size with higher levels of fluorescence on the FL1 vs ALL scatterplot. In addition, there was an extension of the lymphocyte population into the monocyte population (purple) on the IAS vs ALL and the ALL vs PSS scatterplots, leading to an indistinct separation between the two cell populations thereby triggering the BLAST flag.

Peripheral smear showed 90% of the cells appearing as mature-looking lymphocytes with characteristic condensed “soccer ball” pattern chromatin and scant cytoplasm. There was a significant number of smudge cells on the smear. These results are consistent with a diagnosis of chronic lymphocytic leukemia (CLL).

CLL has an insidious onset and is usually discovered by chance during investigation of another problem. In a typical case of CLL, more than 90% of cells are the malignant lymphocytes that resemble normal lymphocytes. Anemia and thrombocytopenia are usually absent at the time of diagnosis and develop later when the bone marrow is replaced by leukemic cells and the spleen becomes enlarged. Immunophenotyping is required to confirm the diagnosis of CLL.