The leukemic blast cells in both cases were small to medium with scant basophilic cytoplasm and several small inconspicuous nucleoli, characteristic of L1 lymphoblasts. Immunophenotypically, they were positive for CD19, CD22, and low-density CD20, with expression of surface immunoglobulin lambda light chain. They were negative for immature (CD34 and terminal deoxynucleotidyl transferase), myeloid, and T-cell-associated markers