Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is characterized by small lymphocytes in the bone marrow, blood and lymphoid tissues. CLL is the most common form of leukemia in U.S. adults and represents 40% of all adult leukemias in Western countries.

Epidemiology

Incidence – 4.2/100,000 (SEER data 2007)
Age – median 79 years
- 80% diagnosed ≥60 years
- Rare in patients <50 years (~10% of cases)
Sex – M>F, 2.8:1
Ethnicity – lower risk in Chinese, Japanese and Filipino ethnicities

Risk Factors

Family member with CLL
- First-degree relative has threefold risk of developing CLL or other lymphoid neoplasm

Clinical Presentation

CLL principally involves bone marrow and blood; 25-50% of patients present as asymptomatic with lymphocytosis found on complete blood count
- Disease may remain indolent for several years until treatment required
Small lymphocytic leukemia (SLL) – different manifestation of CLL if nodes principally involved
- SLL has similar biology and history to CLL; treatment approach is the same
Monoclonal B-cell lymphocytosis (MBL) – asymptomatic patient with <5,000 circulating CLL phenotype cells/mL³ and no node involvement
- Similar to multiple myeloma; typically precedes diagnosis of CLL
- MBL estimated to be present in 5% of adults ≥50 years; however, general screening for MBL is not currently recommended
- MBL progresses into CLL, requiring treatment at a rate of 1% per year
Constitutional symptoms – night sweats, weight loss, fatigue
Adenopathy
- Hepatomegaly
- Lymph nodes – most commonly cervical, supraclavicular, axillary
- Splenomegaly
Extranodal disease – uncommon
- Central nervous system
- Gastrointestinal tract
- Lungs
- Renal
Complications
- Large-cell transformation (Richter syndrome)
- Autoimmune cytopenias

Indications for Testing

Finding of lymphocytosis on CBC; lymphadenopathy in adult >50 years

Criteria for Diagnosis

Diagnostic guidelines for chronic lymphocytic leukemia

Diagnostic Guidelines for Chronic Lymphocytic Leukemia
Criteria	National Cancer Institute Working Group (NCI-WG), 1996	International Workshop on Chronic Lymphocytic Leukemia (IWCLL), 2008
Lymphocytes in peripheral blood (x10⁹/L)	>5	Not specified¹
Morphology	Not specified	Small, mature lymphocytes without visible nucleoli; smudge cells characteristic
Lymphocyte immunophenotype	≥1 B-cell marker (CD19, CD20 or CD23) and CD5 positivity in the absence of other pan-T-cell marker Monoclonal expression of kappa or gamma chain Low-density surface Ig	≥1 B-cell marker (CD19, CD20 or CD23) and CD5 positivity in the absence of other pan-T-cell marker Monoclonal expression of kappa or gamma chain Low-density surface Ig
Atypical cells (eg, prolymphocytes)	<55% and/or <15x10⁹/L	<55% and/or <15x10⁹/L
Lymphocytosis duration	None required	Not specified but must be chronic
Lymphocytes in bone marrow (percent)	≥30	Bone marrow evaluation not required²
¹A value >5x109/L is acceptable with a chronic, absolute increase in blood lymphocytes having characteristic morphology and immunophenotype ²Bone marrow evaluation no longer required for diagnosis but useful to determine extent and pattern of involvement and to clarify cytopenia etiology

Laboratory Testing

Initial testing – CBC with differential, platelets
Lactate dehydrogenase (LD) concentration
Serum testing – monoclonal antibody panels (minimal)
- B-CLL – kappa/lambda, CD5/CD19, CD23, CD10, FMC-7
- T-CLL – CD3/CD4, CD3/CD8, CD5, CD7, CD25, CD30
Diagnosis may be based on lymphocytosis, morphology and immunophenotype (SmIg [weak]; CD5+, CD19+, CD20 [weak], CD23+, CD10-)
CLL FISH panel may aid in diagnosis
- CLL can mimic mantle cell lymphoma; consider ordering for t(11;14) CCND1/IGH

Histology

Bone marrow – not necessary if characteristic phenotype is present (based on IWCLL recommendations)
- If performed – hyper- or normo-cellularity, nodular or diffuse pattern of lymphocytic infiltration in >10% of nucleated cells
- Perform immunophenotyping
Immunohistochemistry – p53 (KRAS) positivity may correlate with genetic p53 mutation

Imaging

Chest x-ray recommended (IWCLL 2008)

Prognosis

Prognostic factors for CLL

Factor	Outcome
Factor	Good	Poor
Stage (Rai and Binet systems)	Rai 0, I Binet A	Rai II, III, IV Binet B or C
Lymphocyte morphology	Typical	Atypical
Bone marrow pattern	Non-diffuse	Diffuse
Lymphocyte doubling time	>12 months	<12 months
Serum markers
LD	Normal	Elevated
Beta-2 microglobulin	Normal	Elevated
Thymidine kinase	Normal	Elevated
Soluble CD23	Normal	Elevated
Flow cytometry
CD38 expression	<30%	>30%
ZAP-70 expression	<20%	>20%
IGV_H gene mutation	>2%	≤2%
Cytogenetics (FISH)
Genetic abnormalities	Normal del(13)(q14) only Trisomy 12+ has neutral effect	del(11)(q22.3) del(17)(p13.1)*
*p53 (KRAS) mutation associated with therapy resistance to alkylating agents, fludarabine, and tyrosine kinase inhibitors (eg, rituximab)

Differential Diagnosis

Benign
- Infection
- Postsplenectomy
- Reactive lymphocytosis
Malignant
- Other non-Hodgkin lymphoma
- Sézary syndrome
- Other leukemia (ALL)

Flow cytometry follow-up to detect minimal residual disease
Hepatitis B – identify infection prior to initiating CD20 monoclonal antibody therapy
- Monitor all patients receiving therapy
Cytomegalovirus antibodies – high risk of CMV reactivation with TKI therapy
- Monitor every 2-3 weeks in patients using alemtuzumab
Herpes simplex virus (HSV) and Pneumocystis jiroveci – risk of reactivation in patients with HIV
- HSV and P. jiroveci testing as indicated

Tests generally appear in the order most useful for common clinical situations

Test name: CBC with Platelet Count & Automated Differential

ARUP #: 0040003

Methodology: Automated Cell Count with Flow Cell Differential

Use:

Test for lymphocytosis

Test name: Lactate Dehydrogenase, Serum or Plasma

ARUP #: 0020006

Methodology: Quantitative Enzymatic

Use:

Test for elevated levels

Test name: Leukemia/Lymphoma Phenotyping (Comprehensive - Whole Blood)

ARUP #: 0096299

Methodology: Flow Cytometry

Use:

Immunophenotyping for diagnosis of CLL

Test name: Leukemia/Lymphoma Phenotyping (Comprehensive - Bone Marrow)

ARUP #: 0095244

Methodology: Flow Cytometry

Use:

Immunophenotyping for diagnosis of CLL

Test name: Chronic Lymphocytic Leukemia Follow up Phenotyping by Flow Cytometry

ARUP #: 0093194

Methodology: Flow Cytometry

Use:

Monitor disease status after CLL has been established by previous flow cytometry immunophenotyping

Test name: Chromosome FISH, CLL Panel

ARUP #: 2002295

Methodology: Fluorescence in situ Hybridization

Use:

FISH panel is performed for CLL prognosis

Specific genomic abnormalities tested for include ATM del(11)(q22.3), D13S319, (13q,14), p53 del(17)(p13.1), and trisomy 12

Test name: Chromosome FISH, Interphase

ARUP #: 2002298

Methodology: Fluorescence in situ Hybridization

Use:

Rule out mantle cell lymphoma

Order in addition to Chromosome FISH, CLL Panel

Specify FISH probe t(11;14) (IGH/CCND1)

ARUP Oncology FISH Probes menu

Test name: Chromosome Analysis, Bone Marrow

ARUP #: 2002292

Methodology: Giemsa-Band Analysis

Use:

Detect chromosome abnormalities in bone marrow

Complex abnormalities and unbalanced translocations are associated with a poorer prognosis

Limitations:

CLL cells can grow slowly in culture and may not be present in the specific cells analyzed; perform in conjunction with CLL FISH panel for increased sensitivity

Follow-up:

Repeat testing as clinically indicated to monitor disease progression

Test name: Chromosome Analysis, Leukemic Blood

ARUP #: 2002290

Methodology: Giemsa-Band Analysis

Use:

Detect chromosome abnormalities in peripheral blood

Complex abnormalities and unbalanced translocations are associated with a poorer prognosis

Limitations:

CLL cells grow slowly in culture and may not be present in the specific cells analyzed; perform in conjunction with CLL FISH panel for increased sensitivity

Follow-up:

Repeat testing as clinically indicated to monitor disease progression

Test name: IgVH Mutation Analysis by Sequencing

ARUP #: 0040227

Methodology: Polymerase Chain Reaction/Sequencing

Use:

Prognosis of CLL diagnosis

Limitations:

Time-sensitive test

Assay is designed for those with a confirmed CLL diagnosis and include sequencing

For diagnoses other than CLL, testing will terminate after amplification and will not include sequencing

Test name: ZAP-70 Analysis by Flow Cytometry