Chronic Lymphocytic Leukemia Diagnostics

Laboratory Tests and Ancillaries

It is important that in patients suspected of CLL, complete blood count (CBC) with differential and platelet count; metabolic panel, including lactate dehydrogenase (LDH) levels and serum beta-2-microglobulin; bilirubin, haptoglobin, reticulocyte count; direct Coombs test or direct antiglobulin test (may help predict autoimmune hemolytic anemia); and hepatitis B screening, if considering CD20 monoclonal antibody therapy, should be requested.  

Flow Cytometry  

Flow cytometry effectively differentiates CLL from other forms of leukemia by identifying the specific cell lineage using antibodies.  

Immunophenotyping is a fast and reliable method of identifying single-cell populations of surface antigens. It uses antibodies or markers to identify the presence and proportion of surface antigens B-cell associated antigens: CD19, CD20 (low), CD23; T-cell antigen: CD5; and surface immunoglobulins: IgM, IgD (low). It is also used for confirmation of the clonality of B cells.  

Cytogenetics and Gene Mutations  

Cytogenetics and gene mutations are used for the determination of the patient’s prognosis and to help select the best treatment option. Fluorescence in situ hybridization (FISH) detects del(17p), del(11q), del(13q), and trisomy 12. Identifying the IGHV mutation status is useful when considering treatment with chemoimmunotherapy. This is preferred over flow cytometry. CpG-stimulated karyotype test is used to identify patients with high-risk disease, particularly for patients receiving Bruton tyrosine kinase (BTK) inhibitor therapy. Elevated levels of serum beta-2 microglobulin (B2M) are associated with overall response, treatment free intervals, and overall survival in patients treated with frontline chemoimmunotherapy.
 
Optional Tests  

Optional tests that may be requested include serum uric acid levels and quantitative serum immunoglobulin test (to determine the patient’s immunological status). Testing for hepatitis C, cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human immunodeficiency virus (HIV) is also suggested.  

Biopsy  

Biopsy is a diagnostic test option when diagnosis cannot be established with flow cytometry alone.  

Lymph Node Biopsy  

Lymph node biopsy may be used to rule out other types of lymphoproliferative diseases and high-grade lymphoma transformation in suspected cases.  

Bone Marrow Biopsy  

Bone marrow biopsy is an option used for the assessment of marrow reserve and to ascertain the nature of cytopenias (anemia, thrombocytopenia) pre- and post-treatment. 

Lumbar Puncture

Lumbar puncture may be used for patients with possible central nervous system (CNS) involvement with overt symptoms.  

Prognostic Markers  

Prognostic markers aid in predicting survival or disease progression beyond clinical staging. It includes serum markers (CD23, thymidine kinase), genetic markers (IGHV gene analysis) and tests for genomic abnormalities (CD38 expression, CD49d and ZAP-70 expression or methylation). 

Imaging

Imaging studies are not routinely used.  

Computed Tomography (CT)  

A CT scan is used to assess tumor load and for the assessment of symptoms. It is also used for baseline assessment of patients enrolled in clinical trials.  

Positron Emission Tomography (PET)  

A PET scan is recommended for localized diseases and to identify occult sites of the disease or histologic transformation.  

Ultrasonography  

An ultrasound may be considered for the detection of lymphadenopathies and organ enlargement.