Chronic Lymphocytic Leukemia (CLL) in Elderly Patients
Key Point
Chronic lymphocytic leukemia is the most common chronic leukemia in elderly patients (>60 years) in Western populations and is increasingly recognized in India. It is a B-cell malignancy characterized by progressive accumulation of functionally incompetent lymphocytes.
Clinical and Immunophenotypic Features of CLL
| Feature | CLL |
|---|
| Median age at diagnosis | 70–72 years |
| Male:Female ratio | 2:1 |
| Presentation | Often asymptomatic (30–50% discovered incidentally) |
| Lymphocytosis | >5,000/μL lymphocytes (often >10,000/μL) |
| Lymphadenopathy | Present in 50–80% of cases |
| Splenomegaly | Present in 25–50% of cases |
| Flow cytometry | CD5+, CD19+, CD23+, CD10−, FMC7− (co-expression of T-cell and B-cell markers) |
| Bone marrow | Lymphocytic infiltration (interstitial or diffuse) |
Immunophenotypic Distinction: CLL vs. Other B-Cell Lymphomas
| Marker | CLL | Lymphoplasmacytic | Marginal Zone |
|---|
| CD5 | + | − | − |
| CD19 | + | + | + |
| CD23 | + | − | − |
| CD10 | − | − | − |
| Surface Ig | Weak | Strong | Weak |
| Monoclonal protein | Rare | Common (IgM) | Rare |
High-YieldNEET PG
The CD5+, CD19+, CD23+ immunophenotype is pathognomonic for CLL. CD5 is a T-cell marker aberrantly expressed on B cells in CLL, which is a key diagnostic feature. The combination of CD5 and CD23 co-expression distinguishes CLL from other B-cell malignancies.
Clinical Pearl
In elderly Indian patients, CLL may present late with advanced-stage disease due to delayed diagnosis. Rai and Binet staging systems are used to stratify prognosis and guide treatment decisions. Early-stage asymptomatic CLL may be managed with "watch and wait" strategy, while symptomatic or advanced-stage disease requires chemotherapy or targeted therapy (BTK inhibitors, BCL2 inhibitors).
Mnemonic: CLL = CD5 + CD19 + CD23 = Classic Chronic Lymphoid Leukemia — the triple marker combination is the immunophenotypic hallmark.
