- Patients must have histologically confirmed mantle cell lymphoma, with documented cluster of differentiation (CD19) or CD20 expression and cyclin D1 (BCL1) by immunohistochemical stains and/or t(11;14) by cytogenetics or fluorescence in situ hybridization (FISH); the diagnosis must be confirmed by formal hematopathology review at the enrolling center, including assessment of Ki-67 proliferation index (=< 30% versus > 30% versus ?indeterminate? Ki-67 index)