Laboratory features

• peripheral blood: (1,2,3)
  • WBC
  • WBC usually greater than 15000 x 10^9 per litre, may be markedly elevated
  • 75-98% of circulating cells may be lymphocytes
  • lymphocyte count is more than 5 x 10^9/l
  • in blood smear, majority of lymphocytes are small, mature appearing with scanty cytoplasm, clumped chromatin, indistinct or absent nucleoli (1,2)
  • red blood cells - distinguish anaemia secondary to bone failure from that due to autoimmune haemolytic anaemia
  • platelets - usually normal; may be low secondary to bone marrow failure or to autoimmune thrombocytopenia
• peripheral blood flow cytometry
  • most valuable test for the confirmation of CLL
  • immunophenotyping should be carried out in all patients who require treatment and is especially important in the following situations
    • in patients with low lymphocyte counts (to confirm the diagnosis of CLL and to exclude reactive lymphocytosis)
    • in patients with atypical lymphocyte morphology (to exclude other B- or T-cell lymphoproliferative disorders) (2)
  • classical immunophenotype of CLL are weak monotypic surface immunoglobulin, CD5, CD19, and CD23 and weak or absent CD79B, CD22 and FMC7 (2)

Additional investigations which could be done include:

• bone marrow aspiration / biopsy - infiltration by lymphocytes
  • bone marrow examination is not carried out routinely except in cases where it is necessary
  • when there is diagnostic difficulty
  • as a prognostic indicator
  • to document the response to therapy
  • to assess haemopoietic reserve
  • as a research investigation
• Coomb's test (direct antiglobulin test ,DAT)
  • positive in 5% of patients
  • should be done in all anaemic patients and before commencing therapy
• serum Ig's - hypogammaglobulinaemia seen in two-thirds of cases dependent on duration of disease; monoclonal gammopathy - often IgM - seen in some cases
• uric acid - often normal; may become elevated with treatment
• imaging - chest X-ray, ultrasound of the abdomen

References:

1. Eichhorst B, Robak T, Montserrat E, et al; ESMO Guidelines Committee. Chronic lymphocytic leukaemia: ESMO clinical practice guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2021 Jan;32(1):23-33.
2. Hallek M, Al-Sawaf O. Chronic lymphocytic leukemia: 2022 update on diagnostic and therapeutic procedures. Am J Hematol. 2021 Dec 1;96(12):1679-705.
3. Walewska R, Parry-Jones N, Eyre TA, et al. Guideline for the treatment of chronic lymphocytic leukaemia. Br J Haematol. 2022 Jun;197(5):544-57.