chronic%20lymphocytic%20leukemia
CHRONIC LYMPHOCYTIC LEUKEMIA

Chronic lymphocytic leukemia (CLL) is a malignant, chronic lymphoproliferative disorder characterized by proliferation and accumulation of monoclonal B-cells in the bone marrow, peripheral blood, lymph nodes, liver and spleen.

It is the most common form of adult leukemia in the Western world but rare in Asians.

Exact etiology is unknown but usually associated with genetic aberrations and lesions.

 

Diagnosis

  • Diagnosis is based on the following criteria:
    • Presence of monoclonal B-cell lymphocytes ≥5 x 109/L in peripheral blood
    • Clonality of circulating B lymphocytes confirmed by flow cytometry
    • Chronic lymphocytic leukemia cells are small, mature-looking lymphocytes with a narrow border of cytoplasm, dense nucleus with no visible nucleoli, & with partially aggregated chromatin
    • Immunophenotype: CD5, CD19, & CD23; low CD20, CD79b & FMC7 (typically negative); CD10 & cyclin D1 negative
  • Assess patient's performance status based on clinical presentation

Classification

Classification of Chronic Lymphocytic Leukemia

  • Two staging systems are being used to predict patient outcome
  • Also used in assessing patients to be included in clinical trials

Chronic Lymphocytic Leukemia Staging Systems

Rai System

  • A staging system based on physical examination & complete blood count results used to assess the degree of tumor burden
  • Stage Description Risk Status1
    0 Lymphocytosis >5 x 109/L & >40% lymphocytes in bone marrow Low
    I Stage 0 with enlarged node(s) Intermediate
    II Stage 0-I with splenomegaly, hepatomegaly, or both Intermediate
    III Stage 0-II with Hgb <110 g/L or Hct <33% High
    IV Stage 0-III with platelets <100 x 109/L High
    1Used in the modified Rai classification
Binet System
  • Based on the number of areas with lymph nodes >1 cm in diameter or organomegaly, & the presence of anemia or thrombocytopenia
  • Involved areas include head & neck, axilla, groins including superficial femorals, spleen, & liver
    Stage Description
    A Hgb ≥10 g/dL, platelets ≥100,000/mm3, & <3 enlarged areas
    B
    Hgb ≥10 g/dL, platelets ≥100,000/mm3, & ≥3 enlarged areas
    C Hgb <10 g/dL, platelets <100,000/mm3, & any number of enlarged areas

Functional Status

  • Used to assess how a disease affects the daily activities of a patient
  • Commonly used performance status scoring systems:
    • Karnofsky performance status scale
    • Eastern Cooperative Oncology Group (ECOG) performance scale

Physical Examination

  • Node-bearing areas (eg Waldeyer’s ring)
  • Spleen, liver enlargement
  • Skin examination: presence of macules, papules, plaques, nodules, ulcers, blisters

Laboratory Tests


Essential Tests
  • Complete blood count, with differential & platelet count
  • Metabolic panel, including lactate dehydrogenase (LDH) levels & serum beta-2-microglobulin
  • Direct Coomb’s test/direct antiglobulin test - may help predict autoimmune hemolytic anemia
  • Hepatitis B screening - if considering CD20 monoclonal antibody therapy
Optional Tests
  • Serum uric acid levels
  • Quantitative serum immunoglobulin test - to determine patient’s immunological status
  • Testing for hepatitis C, cytomegalovirus (CMV) & human immunodeficiency virus (HIV) is also suggested
Molecular & Genetic Analysis
  • Effectively differentiates chronic lymphocytic leukemia (CLL) from other forms of leukemia by identifying the specific cell lineage using antibodies


Immunophenotyping by Flow Cytometry

  • Fast & reliable method of identifying single cell populations of surface antigens
  • Uses antibodies/markers to identify the presence & proportion of surface antigens by using antibodies/markers
    • B-cell associated antigens: CD19, CD20 (low), CD23
    • T-cell antigen: CD5
    • Surface immunoglobulins: IgM, IgD (low)
  • Used for confirmation of clonality of B cells

Fluorescence in situ hybridization (FISH)

  • Detects del(17p), del(11q), del(13q), & trisomy 12

TP53 sequencing

  • Commonly used for determination of the patient’s prognosis & to help in selecting the best treatment option

Biopsy

  • Optional diagnostic test when diagnosis cannot be established with flow cytometry alone

Lymph node biopsy

  • May be used to rule out other types of lymphoproliferative diseases & high grade lymphoma transformation in suspected cases

Bone marrow biopsy

  • Optional test used to ascertain the nature of cytopenias (anemia, thrombocytopenia) pre- & post-treatment

Lumbar Puncture

  • May be used for patients with possible central nervous system (CNS) involvement with overt symptoms

Imaging

  • Imaging studies are not routinely used

Computed Tomography (CT)

  • Used to assess tumor load & for the assessment of symptoms
  • Also used for baseline assessment of patients enrolled in clinical trials

Positron Emission Tomography (PET)

  • Recommended for localized diseases & to identify occult sites of the disease or histologic transformation

Ultrasonography

  • May be considered for the detection of lymphadenopathies & organ enlargement

Screening

Prognostic Markers
  • Aids in predicting survival or disease progression beyond clinical staging
  • Includes serum markers (CD23, thymidine kinase, serum β2-microglobulin [B2M]), genetic markers (immunoglobulin heavy chain variable [IGHV] gene analysis) & tests for genomic abnormalities (CD38 expression, CD49d & ZAP-70 expression or methylation)
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