CD7 and acute lymphoblastic leukemia: B-lineage ALL (80%) usually expresses cytoplasmic CD22, CD19, CD10 in the “common” subset, and clonal surface immunoglobulin in Burkitt leukemia; T-lineage ALL (20%) does express cytoplasmic CD3, CD7, CD1a+ in cortical T-ALL, and surface CD3 in mature T-ALL.