Chronic Lymphocytic Leukaemia

Lymphocytosis is a common indication for a film and low grade lymphoproliferative disorder is common in older patients. The course of the illness is quite heterogenous, but some patients can have white counts in several hundreds without complication requiring treatment. 

CLL is similar in appearance to other low grade lymphoproliferative disorders and is indistinguishable morphologically from many other low grade B NHLs. Lymphocytes are increased and are normal in appearance being small with mature chromatin. It's worth noting that the clone on flow cytometry must be higher than 5x10⁹/L in order for a diagnosis of CLL (and the phenotype must match) so where the lymphocyte count is lower than this, the diagnosis would be MBL (monoclonal B cell lymphocytosis). Smear cells are common in many low grade LPDs but are especially prominent in CLL.

The characteristic phenotype in CLL is outlines in the Matutes score - CD5+, CD23+, CD19+, CD79b weak, FMC7 negative. Note that any CD5+ lymphocytosis which has a CLL score of <3 should be tested to exclude mantle cell lymphoma.

In this film, the red cells show some EDTA change. This is where the cell outline becomes irregular, mimicking echinocytes or acanthocytes and occurs when the patient sample is left for more than a few hours before the film is made. A fresh film will confirm whether this is a genuine finding or not.

There is no evidence of anaemia or thrombocytopenia. These are important findings in CLL. Cytopenis can be because of bone marrow failure or autoimmune destruction, but either way significant cytopenias suggest treatment may be required. In this film, neutrophils are also normal.