Morphologic and immunophenotypic evaluation. (A-B) Low (original magnification ×400) and high (original magnification ×1000) magnification of Wright-Giemsa stained peripheral blood smear show circulating small lymphocytes, some of which contain cytoplasmic vacuoles. (C) Wright-Giemsa stained bone marrow aspirate smear at high (original magnification ×1000) magnification shows similar small lymphocytes with cytoplasmic vacuoles. (D) Hematoxylin and eosin–stained bone marrow biopsy (original magnification ×400) shows extensive infiltration with small lymphocytes. (E-G) Immunohistochemical stains indicate that lymphocytes are positive for CD20 (E) and cyclin D1 (F) but are negative for SOX11 (G). (H-I) Immunophenotyping by flow cytometry demonstrates λ light chain–restricted B lymphocytes are positive for CD20 (red) and CD19 (orange), partially positive for CD5, and negative for CD200.