Pathologic features of SMZL.

(A) Splenic cut surface in typical SMZL. Note the widespread micronodular appearance. (B) Histologic picture of spleen in SMZL. Widening of the marginal zone is evident; in initial phase, the differentiation with a reactive marginal expansion can be impossible (hematoxylin and eosin, × 125). (C) Splenic sinuses are characterized by the presence of mature lymphocytes (hematoxylin and eosin, × 500). (D) CD20 positivity in SMZL. Note sinusal involvement (avidin-biotin-peroxidase complex [ABC] method, × 250). (E) Imprint cytology of SMZL. Medium-sized lymphoid cells with clumped nucleus and villous cytoplasmic borders (arrow; Giemsa, × 1000). (F) Bone marrow biopsy in a typical case of SMZL shows peculiar intrasinusoidal infiltration (arrows; × 400). (G) Intrasinusoidal infiltration in bone marrow biopsy (Cd45RB; ABC method, × 500). (H) Rarely, lymphoid cells infiltrate bone marrow in a perisinusoidal pattern (CD20; ABC method, × 300). (I) Ultrastructure of circulating villous lymphocytes.(uranyl acetate-lead citrate, × 2000). (J) CD79a positivity in a hilar splenic lymph node involved by SMZL (ABC method, × 500). (K) Liver involvement in SMZL. Lymphoid infiltration is present in portal tract and in sinusoids (hematoxylin and eosin, × 250). (L) Sinusoidal involvement in liver biopsy is highlighted by immunocytochemistry (CD45 RA; ABC method, × 250).