CD19 and lymphoma: Cases of B-lymphoblastic leukemia/lymphoma may express markers reflective of the various stages of B cell maturation, including the earliest, pro-B stage (CD19, cytoplasmic CD79a, cytoplasmic CD22, TdT, negative for CD10, and IgM), the intermediate or common-B stage (CD10 positive and negative for IgM), and the later pre-B stage (positive for cytoplasmic and surface IgM) [2,4].