Characterization of immunophenotypic aberrancies in adult and childhood acute lymphoblastic leukemia: A study from Northern India.

BACKGROUND

Identification of aberrant antigen expression is important in characterizing neoplastic population among non.neoplastic bone marrow counterparts and further in the detection of minimal residual disease. (MRD). Flow cytometry (FCM) is an important tool in identifying aberrant phenotypes. Incidence of aberrant phenotypes varies considerably in independent studies and its association with prognostic factors is still debatable.

AIM

To identify the prevalence of aberrant phenotypes on immunophenotyping in a large series of de novo acute lymphoblastic leukemia (ALL) and to evaluate any association with initial clinical and hematological features.

MATERIALS AND METHODS

In the current study, 303 patients of de novo ALL were included from the Department of Hematology, PGIMER, Chandigarh during the time period (July 2010 to June 2012). The immunophenotype of all cases of ALL was studied using FCM.

RESULTS

Aberrant myeloid antigen expression was seen in 42.5% cases. Most frequent aberrant myeloid antigen was CD13 (32.2% cases), followed by CD33 (27.2% cases) and CD117 (18.5% cases). The expression of CD117 was relatively frequent in comparison to earlier reports which describe its rare expression. Adult T- ALL showed higher expression of CD33 and CD117 than pediatric T-ALL (P = 0.032 and 0.043, respectively). Myeloid antigen expression in ALL was associated with lower WBC count (P < 0.05) and lower number of peripheral blasts (P < 0.05). Expression of CD34 was higher in My + ALL group (P < 0.05) than My- ALL group.

CONCLUSION

In summary, CD117 is a relatively frequently expressed myeloid marker contrary to earlier reports which describes its rare expression. Pediatric and adult ALL cases with low blast count and CD34 positivity are more likely to express aberrant myeloid markers. Current study also supports that myeloid antigen expression in both adult and pediatric ALL is not associated with adverse presenting clinical and biological features.