#00063489

(a) Peripheral blood smear, wright and Giemsa stain, (original magnification, x1000) showing a predominance of small cells with condensed chromatin and scant cytoplasm. Smudge cells are also present. (b-e) Flow cytometric analysis of aberrant B lymphocytes expressing CD5 and CD23. (b) The dot plot shows side scatter versus CD45, the lymphocyte gate is demarcated. (c)  Dot plot of CD5 versus C19 shows three distinct populations of cells: C19+ CD5- cells, in green, represent normal B lymphoctytes; CD5+ CD19- cells, in blue, represent normal T lymphocytes, CD5+ C19+ cells, in purple, represent aberrant B lymphocytes. (d) Dot plot of CD23 versus CD20 shows that the aberrant B lymphocytes are positive for CD23 and have dim CD20 expression. (e) Dot plot of Lamba versus Kappa highlights the reduced immunoglobulin light chain expression of the aberrant B lymphocyte population (purple) in comparison to the normal B lymphocytes (green). In the context of aberrant expression of CD5, a pan T-cell antigen, CD23, and CD200 (not shown), the above findings are most consistent with an abnormal B-cell lymphoproliferative disorder with bi-clonal restriction of either surface kappa or lambda light chain as opposed to an atypical reactive polyclonal lymphocytosis.