Based on the immunohistochemical analysis, SMZL cells express B cell-associated antigens (CD19, CD20, and CD22), surface immunoglobulins, and BCL2, but not CD5, CD10, CD23, CD11c, or CD43 (13) These characteristics can be used for the differential diagnosis of chronic lymphocytic leukemia, mantle cell lymphoma, and follicular lymphoma. The gene discussed is CD5; the disease is B-cell chronic lymphocytic leukemia.