Fast Five Quiz: Chronic Lymphocytic Leukemia Differential Diagnosis

Karl J. D'Silva, MD


March 09, 2020

Peripheral blood flow cytometry is considered the most valuable test to confirm a diagnosis of CLL. It is used to confirm the presence of circulating clonal B lymphocytes expressing CD5, CD19, CD20 (dim) and CD23 and an absence of FMC-7 staining.

Although flow cytometry is essential to confirm clonality, a CBC with differential in patients with CLL shows absolute lymphocytosis, with > 5000 B lymphocytes/µL. Lymphocytosis must be present for more than 3 months. However, the presence of a cytopenia caused by clonal bone marrow involvement confirms the diagnosis of CLL irrespective of the peripheral B-lymphocyte count.

It may be important to obtain serum quantitative immunoglobulin levels in patients who develop repeated infections. Monthly intravenous immunoglobulin administration in patients with low levels of immunoglobulin G (< 500 mg) may be beneficial for lessening the frequency of infectious episodes.

Bone marrow aspiration and biopsy with flow cytometry are not mandatory in all cases of CLL, but in some cases, they may be needed to establish the diagnosis and to assess other complicating features, such as anemia and thrombocytopenia.

Learn more about diagnostic considerations in CLL.


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