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 BCL2; the disease is mantle cell lymphoma.