Peripheral blood cytology and BM pathology. (A) Peripheral blood smear lymphocyte cytology. Morphologic heterogeneity of the lymphocytic population was apparent in most CBL-MZ cases. (B) Patterns of BM lymphocytic infiltration by predominately small B-lymphocytes showing interstitial with minor extent of intrasinusoidal pattern of infiltration (A), interstitial pattern of infiltration (B), and paratrabecular and interstitial pattern of infiltration (C). In all images, B cells are depicted with the CD20 antibody.