CD19 and acute lymphoblastic leukemia: Upon reexamination of the immunophenotype of our historic pediatric ETP-ALL cases, we identified 2 of 13 patients with ETP-ALL for whom immunophenotypic data were available and who expressed CD19 in contrast to 0 of 74 patients with T-ALL (P = 0.021, Fisher’s exact test, Supplemental Table 4).