C h r o n i c L y m p h o c y t i c L e u k e m i a
General
• CLL is a clonal disorder of lymphocytes characterized by a sustained 
proliferation of mature-appearing lymphocytes.
• Most cases of CLL are of B-cell type, but a minority are of T-cell type.
Clinical Features
• Patients are usually older (>40).
• Asymptomatic, or symptoms related to organ infiltration (lymphadenopathy,
hepatosplenomegaly).
Morphology
Blood
• Proliferation of mature lymphocytes (small, with clumped chromatin).
Bone marrow
• Proliferation of mature lymphocytes.
• The more marrow involved, the worse the prognosis.
Immunophenotype
• Positive for:
• monoclonal surface Ig
• B-cell antigens (CD19, CD20)
• a T-cell antigen (CD5)
• Negative for: TdT (a protein expressed by lymphoblasts).
Laboratory Findings
• WBC increased (ranges from almost normal, in early stages, to markedly
increased, in later stages of disease).
• Hypogammaglobulinemia in 50% of cases.
Pathophysiology
• A small number of cases show rearrangement of bcl-2. This leads to
over-expression of bcl-2, prevention of apoptosis, and cell immortality.
• Chromosomal abnormalities: trisomy 12 is the most common
(bad prognosis).
Treatment and Prognosis
• Staging systems (Rai, Binet) predict median survival.
• Prognosis is variable (most patients live many years, a smaller number
have a rapid clinical course).
• Treatment, when necessary, includes corticosteroids and chemotherapy.
Treatment with chemotherapy is usually not initiated until later in the course
of the disease. This is because with current chemotherapeutic regimens, the
disease cannot be cured, only alleviated. So to keep chemotherapy
side effects to a minimum, treatment is usually not given until symptoms
become pronounced.
• Most patients (70%) die of infection. In some patients, CLL transforms into
an aggressive lymphoma (Richter's transformation).
