1.1.3 Local institution lymphocyte phenotype must reveal a predominant B-cell monoclonal population sharing a B-cell marker (CD19, CD20, CD23, CD24) with the CD5 antigen, in the absence of other pan-T-cell markers. Additionally, the B-cells must be monoclonal with regard to expression of either κ or λ and have surface immunoglobulin expression of low density. Patients with bright surface immunoglobulin levels must have CD23 co-expression.