[1213] Detection of Monoclonal B-Cell Lymphocytoses by Flow Cytometry in Patients with T-Cell Large Granular Lymphocyte Leukemia

MT Howard, J Maciejewski, ED Hsi. Cleveland Clinic, Cleveland

Background: T cell large granular lymphocyte leukemia (T-LGL) has been associated with monoclonal gammopathy of undetermined significance (MGUS) and low grade B cell lymphoma. Routine flow cytometry (FC) may identify patients with a low grade B-cell lymphoma or with a monoclonal B-cell lymphocytosis (MBL). We retrospectively reviewed our experience with T-LGL patients who underwent FC during their disease course to determine the incidence of detecting an abnormal B-cell population.
Design: 45 patients with T-LGL were studied based on available 4-color FC data. FC data files from tubes with antibodies to CD5/CD19/CD23/CD45 and CD19/CD45// were reviewed retrospectively. The tube containing surface immunoglobulin (sIg) was acquired with a live-gate on CD19+ events, collecting 20,000 events or 0.2 ml of sample. Specimens were considered positive for a B-cell dyscrasia if one of the following criteria were met: 1) B-cells with a : > 10:1 or : < 0.2; 2) > 80% of B-cells were sIg negative; 3) B-cells with a specific disease phenotype were found as a subset of a sIg polytypic B-cell population, though not in sufficient quantity to cause an abnormal overall : ratio. In addition, the population of abnormal B-cells must have been a cluster of greater than 100 events.
Results: 45 patients were included, with a mean age of 62 years. The mean number of abnormal B-cells analyzed was 4533 (range 240-17813). 14/45 patients had total absolute lymphocyte counts greater than 4.0 x 10^9/l, though these lymphocytoses were due to the underlying T-LGL. 5 patients met criteria (11%) for a B-cell dyscrasia, with a mean age of 57 years. Of these 5 patients, 2 patients had a sIg negative population consisting of greater than 80% of B-cells, while 3 patients had an abnormal kappa/lambda ratio. Chart review of the affected patients showed that 3 had evidence of an M-protein while 1 had hypogammaglobulinemia. Although 3 patients had CD19+ CD5+ populations of B-cells, none of these patients had such a population in a quantity greater than 4.0 x 10^9/l (max 3.72 x 10^9/l).
Conclusions: 11% of T-LGL patients in this series had a concurrent B-cell dyscrasia by FC that can be described as an MBL. This incidence appears higher than that published for the general population. Altered immune status of T-LGL patients may be an etiologic factor, but this remains speculative. Further evaluation of the clinical significance of these MBLs is warranted.
Category: Hematopathology

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 187, Wednesday Morning