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Chronic lymphocytic leukemia and prolymphocytic leukemia: a clinicopathological reappraisal
Insights
This study classified chronic B-cell leukemia into three groups based on prolymphocyte percentage. Absolute prolymphocyte count and spleen size independently predict survival in leukemia patients.
Area of Science:
- Hematology
- Oncology
- Cell Biology
Background:
- Chronic B-cell leukemia (CLL) is a heterogeneous disease.
- Subclassification is crucial for prognosis and treatment.
- Prolymphocytes (PROL) are key indicators in B-cell leukemias.
Purpose of the Study:
- To classify 300 chronic B-cell leukemia cases into distinct groups.
- To identify clinical and laboratory features differentiating these groups.
- To determine prognostic factors for patient survival.
Main Methods:
- Categorization of patients based on circulating prolymphocyte percentage (%PROL): CLL (≤10%), prolymphocytic leukemia (PLL) (>55%), and an intermediate CLL/PL group (11%-55%).
- Analysis of clinical features (splenomegaly, lymphadenopathy), membrane markers (M rosettes, P67 antigen, FMC7, SmIg), and cell volume.
- Multivariate regression analysis to identify independent prognostic factors.
Main Results:
- Three groups identified: typical CLL (174 cases), PLL (42 cases), and CLL/PL (84 cases).
- CLL/PL group showed mixed features but closer membrane marker affinity to CLL.
- Prolymphocytes in PLL and CLL/PL were larger than CLL lymphocytes.
- Absolute prolymphocyte count (ABS PROL) > 15 x 10(9)/l and spleen size > 8 cm were independent prognostic indicators.
- Median survival: PLL (3 years), CLL (8 years). CLL/PL patients with high ABS PROL had poor prognosis similar to PLL.
Conclusions:
- Classification based on %PROL is valuable for understanding B-cell leukemia subtypes.
- ABS PROL and spleen size are critical independent prognostic markers.
- Some CLL/PL cases may transform into a PLL-like disease, impacting survival.
Abstract:
A series of 300 cases of chronic B-cell leukemia was studied in relation to clinical and laboratory features, and three groups were identified on the basis of the percentage of circulating prolymphocytes (%PROL): typical CLL less than or equal to 10% PROL, 174 cases; PLL greater than 55% PROL, 42 cases; and an intermediate group CLL/PL (11%-55% PROL), 84 cases. Some features of the CLL/PL group resemble those of PLL, such as a disproportionate splenomegaly in relation to the degree of lymphnode involvement. However, membrane markers suggested a closer affinity of CLL/PL with CLL [high percentage of M rosettes, expression of the P67 (T1) antigen, and low reactivity with the McAb FMC7], although high-density SmIg was found in one-third of CLL/PL, as well as in the majority of the PLL cases. Cells volume measurements demonstrated that the prolymphocytes of both PLL and CLL/PL are significantly larger than the homogeneous population of small lymphocytes of typical CLL. Followup studies of the PB picture in CLL and CLL/PL showed that the majority of patients maintain a relatively stable percentage of PROL, but a progressive prolymphocytoid transformation to a PLL-like disease may occur in some cases. On univariate analysis of survival, seven features of disease had a high prognostic values for the whole group of patients: %PROL, absolute number of PROL (ABS PROL), WBC, spleen size, M rosettes, SmIg intensity, and age. However, only ABS PROL (greater than 15 X 10(9)/l) and spleen size (greater than 8 cm) were shown to be independent prognostic features on a multivariate regression analysis. The median survival time of patients with PLL (3 years) was significantly shorter than the median of 8 years for patients with CLL. Within the heterogeneous CLL/PL group, patients with ABS PROL greater than 15 X 10(9)/l (two-thirds) had a median survival time as bad as for PLL patients, whereas the median has not been reached for those with ABS PROL less than 15 X 10(9)/l.