Peripheral blood flow cytometry and bone marrow biopsy (100% cellularity) demonstrated a blast population positive for CD19, TdT, CD38, CD79a, and HLA-DR and negative for MPO, CD10, CD13, CD20, CD22, CD33, and CD34—consistent with a diagnosis of precursor B-ALL. Here, CD22 is linked to precursor B-cell acute lymphoblastic leukemia.