Chronic Lymphocytic Leukemia (CLL) Workup

Updated: Jan 30, 2023
  • Author: Mohammad Muhsin Chisti, MD, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Approach Considerations

In patients with CLL, the complete blood count (CBC) with differential shows absolute lymphocytosis, with more than 5000 B-lymphocytes/µL. Lymphocytosis must persist for longer than 3 months. Clonality must be confirmed by flow cytometry. The presence of a cytopenia caused by clonal bone marrow involvement establishes the diagnosis of CLL regardless of the peripheral B-lymphocyte count.

Patients with fewer than 5000 B-lymphocytes/µL with lymphadenopathy and without cytopenias more likely have small lymphocytic lymphoma (SLL), although this diagnosis should be confirmed by lymph node biopsy.

Patients with a clonal B-cell population less than 5000/µL without lymphadenopathy or organomegaly, cytopenia, or other disease-related symptoms have monoclonal B-lymphocytosis (MBL). MBL will progress to CLL at a rate of 1-2% per year [2] .

Microscopic examination of the peripheral blood smear is indicated to confirm lymphocytosis. It usually shows the presence of smudge cells, depicted in the image below, which are artifacts from lymphocytes damaged during the slide preparation.

Peripheral smear from a patient with chronic lymph Peripheral smear from a patient with chronic lymphocytic leukemia, large lymphocytic variety. Smudge cells are also observed; smudge cells are the artifacts produced by the lymphocytes damaged during the slide preparation.

Large atypical cells, cleaved cells, and prolymphocytes are also often seen on the peripheral smear and may account for up to 55% of peripheral lymphocytes. If this percentage is exceeded, prolymphocytic leukemia (B-cell PLL) is a more likely diagnosis [2] .

Peripheral blood flow cytometry is the most valuable test to confirm a diagnosis of CLL. It confirms the presence of circulating clonal B-lymphocytes expressing CD5, CD19, CD20(dim), CD23, and an absence of FMC-7 staining. This immunotype differentiates CLL from other hematologic disorders in the differential diagnosis (see DDx).

Consider obtaining serum quantitative immunoglobulin levels in patients developing repeated infections, because monthly intravenous immunoglobulin (IVIG) administration in patients with low levels of immunoglobulin G (IgG), especially levels less than 500 mg/100 mL, may be beneficial in reducing the frequency of infections.

Bone marrow aspiration and biopsy with flow cytometry is not required in all cases of CLL. However, it may be necessary in selected cases to establish the diagnosis and to assess for complications, including cytopenias, which may be explained by concomitant hematologic disorders.

Ultrasonographic studies of the liver and/or spleen may demonstrate hepatomegaly and/or splenomegaly in patients with CLL. Computed tomography (CT) scans of the chest, abdomen, or pelvis are generally not required for staging purposes in CLL. However, imaging can be especially helpful in the assessment of patients with clinical manifestations suggesting obstruction due to lymph node compression of organs or internal structures, such as obstructive uropathy or airway compromise.

Serum free light chain (FLC) assays remain a research tool. Monoclonal and polyclonal abnormalities have been detected in about one-half of CLL cases and appear to be associated with a shorter time from diagnosis to disease progression requiring treatment (time to first treatment; TTFT). [23, 24]


Chromosomal Testing

Although not necessary for the diagnosis or staging of CLL, additional molecular testing now exists that may help predict prognosis or clinical course as well as guide treatment choices. [25, 26] The National Comprehensive Cancer Network regards the following tests as informative, but not essential, for determining prognosis, therapy, or both in CLL [5] :

  • Fluorescence in situ hybridization (FISH) to detect trisomy 12, del(11q), del(13q), del(17p)
  • TP53 sequencing
  • Molecular analysis to detect immunoglobulin heavy chain region (IgV H) mutation status
  • If IgV testing is not available, determination of CD38 and ZAP-70 expression by flow cytometry, methylation, or immunohistochemistry as surrogate markers

However, a systematic review and meta-analysis by Parikh and colleagues recommended that FISH and IGVH status be performed as standard clinical tests for all patients with newly diagnosed CLL, in those countries with the resources to do so. These authors argue that use of these tests allows the application of powerful prognostic indices to CLL cases. [27]

Favorable prognostic findings include the following [5] :

  • FISH - Deletion in the long arm of chromosome 13 [del(13q)] as a sole abnormality
  • TP53 - Wild-type
  • IgV H -  > 2% mutation

Unfavorable prognostic findings include the following [5] :

  • FISH - Deletion in the short arm of chromosome 17 [del(17p)] or the long arm of chromosome 11 [del(11q)] 
  • TP53 - Mutated
  • IgV H -  ≤2% mutation
  • Complex karyotype -  ≥3 unrelated chromosome abnormalities in more than one cell on karyotype

In addition to a worse prognosis, patients with del(17p) tend to have resistance to therapy with alkylating agents and purine analogues, while those with del(11q) typically have bulky lymphadenopathy at presentation. The poor prognosis seen with del(17p) and del(11q) are independent of the disease stage at presentation. Patients with these abnormalities may benefit from treatment with the monoclonal antibody alemtuzumab, which is a monoclonal antibody against CD52 that has proved effective in patients with high-risk genetic markers such as those noted above. [28, 29, 30, 2] However, none of the poor prognostic markers has been validated as an indication to initiate treatment in asymptomatic patients. [4]

MicroRNA analysis remains a research tool. Visone et al reported that decreases in levels of miR-181b, the most dysregulated microRNA, correlate with progressive disease; a drop of ≥ 50% between sequential samples and/or a baseline miR-181b value ≤ 0.005 differentiate progressive from stable CLL. [31]


Bone Marrow Aspiration and Biopsy

Bone marrow aspiration and biopsy with flow cytometry is not required in all cases of CLL, but it may be necessary in selected cases to establish the diagnosis and to assess other complicating features such as anemia and thrombocytopenia. For example, bone marrow examination may be necessary to distinguish between thrombocytopenia due to peripheral destruction and that due to marrow infiltration.

Consider a lymph node biopsy if lymph node(s) begin to enlarge rapidly in a patient with known CLL, to assess the possibility of transformation to a high-grade lymphoma. When such transformation is accompanied by B symptoms, including fever, weight loss, and pain, it is termed Richter syndrome (see Presentation/History and Physical Examination).



Two staging systems are in common use for CLL: the modified Rai (Rai-Sawitsky) staging in the United States and the Binet staging in Europe. Neither is completely satisfactory, and both have often been modified. Because of its historical precedent and wide use, the modified Rai system is described first, followed by the Binet. See also Chronic Lymphocytic Leukemia Staging. These CLL staging systems have been unable to provide information regarding disease progression due to its heterogeneity.

The newest CLL staging system, the International Prognostic Index for Chronic Lymphocytic Leukemia (CLL-IPI), was published in 2016. It is designed to serve as a simple, reliable, and easily applicable method of risk stratification for patients with CLL. [32]

Modified Rai staging

The modified Rai staging system categorizes patients into low-, intermediate-, and high-risk groups, as follows:

  • Low risk (stage 0 in the original version) – Lymphocytosis in the blood and marrow only (25% of presenting population) [4]

  • Intermediate risk (formerly stages I and II) – Lymphocytosis with enlarged nodes in any site or splenomegaly and/or hepatomegaly (50% of presentations)

  • High risk (formerly stages III and IV) – Lymphocytosis with disease-related anemia (hemoglobin < 11 g/dL) or thrombocytopenia (platelets < 100 × 109/L) (25% of all patients)

Binet staging

The Binet staging system categorizes patients according to the number of lymph node groups involved. The areas of lymph node involvement considered are the head and neck, including the Waldeyer ring; axillae; groins; a palpable spleen; and a palpable liver. [2]

  • Stage A – Hemoglobin 10 g/dL or higher, platelets 100 × 10 9/L or higher, and up to two of the above areas involved.
  • Stage B – Hemoglobin and platelet levels as in stage A and three or more of the above lymph node areas involved
  • Stage C – Hemoglobin less than 10 g/dL and/or platelets less than 100 × 10 9/L

International Prognostic Index for Chronic Lymphocytic Leukemia

The CLL-IPI is used to determine the prognosis of patients and in turn help in treatment decision making. A weighted gradient is determined using the following 5 factors [32] :

  • Patient age
  • Clinical stage (Rai or Binet)
  • Serum B2 microglobulin level
  • Mutational status of immunoglobulin heavy chain variable ( IGVH)
  • Deletion 17p (FISH) and/or TP53 mutation

See the CLL-IPI calculator. For treatment considerations based on CLL-IPI risk category, see the table below.

Table 2. CLL-IPI prognostic index [32] (Open Table in a new window)

CLL-IPI category Overall Survival at 5 years Treatment Recommendation
Low risk 93.2% Do not treat
Intermediate risk 79.3% Treat only if symptomatic 
High risk 63.3% Treatment indicated; however, can consider no treatment if asymptomatic
Very high risk 23.3% If treatment needed, do not use chemotherapy; instead, use targeted agent or clinical trial