However, KRAS activation enhanced extramedullary hematopoiesis of MA4-expressing cell lines and CD34(+) HSPCs that was associated with leukocytosis and central nervous system infiltration, both hallmarks of infant t(4;11)(+) B-ALL.
In conclusion, CD34 expression in APL is a unique clinical feature associated with leukocytosis and atypical morphology with hypogranular pattern and is associated with a poor clinical outcome.
Patients with Ph-positive ALL were older and had a significantly lower incidence of anemia and a higher incidence of peripheral leukocytosis, FAB L2 (French-American-British) morphology, common acute lymphocytic leukemia antigens (CALLA), and CD34 marker positivity.