Acknowledgments: the authors wish to acknowledge Neeraj Kumar for technical assistance Manuscript received on

Cases of mantle cell lymphoma with indolent behavior have been reported, but are poorly identified by current clinical risk models. Early studies found peripheral blood involvement to be an adverse prognostic factor; however, cases of a seemingly indolent variant of mantle cell lymphoma, characterized by peripheral blood involvement and minimal nodal disease, have been incompletely described, particularly with regard to bone marrow findings. We report a series of leukemic phase mantle cell lymphomas with a non-progressive or slowly progressive course. Design and Methods Cases presenting with mantle cell lymphoma limited to the peripheral blood/bone marrow from 2000-2010 were identified. Diagnoses were established by morphology, flow cytometric analysis and requisite evidence of IGH-CCND1 @ by fluorescence in-situ hybridization or t(11;14)(q13;q32) by cytogenetics. Patients with lymphadenopathy, splenomegaly and gastroin-testinal symptomatology were excluded. Results Patients (n=8, median age 60.5 years) were asymptomatic with mild lymphocytosis (8.7¥109/L