Chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a hematological malignancy characterized by the proliferation of mostly mature but abnormal leukocytes. 

Epidemiology

Chronic lymphocytic leukemia is considered the most common type of leukemia in the Western hemisphere; its prevalence in Europe and North America ranges from 29-38% of all leukaemias ¹. It primarily affects adults 65-70 years of age ³.

Diagnosis

The diagnosis is generally established by a bone marrow biopsy and immunophenotyping.

Clinical presentation

Up to half of the patients can be asymptomatic with the disease being incidentally discovered by routine blood workup ³. Patients may sometimes present with hepatomegaly, splenomegaly or both and/or hemolytic anemia.

Pathology

It is a B-lineage neoplasm of prefollicular center cells that is usually associated with circulating neoplastic small lymphocytes. From a morphologic and immunophenotypic perspective, the malignant cells of chronic lymphocytic leukemia tend to be identical to those of nodal-based small lymphocytic lymphoma (SLL), and these two malignancies are thought to represent different manifestations of the same disease ¹. This is reflected in the latest WHO classification of haematolymphoid tumors (5^th edition).

Staging

There are two common staging systems in use which are:

• Rai staging system

• Binet staging system

Radiographic features

Imaging may identify various features of the disease such as splenomegaly, hepatomegaly +/- lymphadenopathy, although these are not specific to the disease.

MRI

As with other types of bone marrow infiltrative disease, it is possible to see a diffusely hypointense signal of bone structures on T1, easier to see on spinal MRI.

Treatment and prognosis

Chronic lymphocytic leukemia treatment is offered in the presence of active disease, which is characterized by any of the listed below ⁷: 

• presence of B symptoms

• progressive bone marrow failure

• extensive or rapidly progressing lymphadenopathy

• massive or rapidly progressive splenomegaly

• uncontrolled autoimmune cytopenias

• rapid lymphocyte doubling time: either occurring in <6 months or when there is an increase of 50% in ≤2 months

About one-third of patients with chronic lymphocytic leukemia will never require treatment ⁷. 

Complications

Richter transformation: is defined as a diffuse large cell lymphoma, occurring by transformation of chronic lymphocytic leukemia ^2,4.

See also

• WHO classification of haematolymphoid tumors

• leukemia