Morphological and immunohistochemical features of SMZL-T. (A) Case SMZL058T showing a lymph node with a diffuse proliferation composed of large lymphocytes with a centroblastic appearance (hematoxylin and eosin stain, original magnification ×20). (B-C) Detail of case SMZL07T showing the interphase between a transformed area (left) and an area with remnant marginal splenic B-cell lymphoma (right). In panel B, hematoxylin and eosin stain (original magnification ×20); and in panel C, immunohistochemical staining for Ki67 showing the different proliferative index between both areas (original magnification ×20). (D-G). Case SMZL012T showing the spleen infiltrated by a lymphoid proliferation arranged in a nodular growth pattern, original magnification ×4 (D), constituted of large, atypical cells (inset, original magnification ×40). (E) These cells were positive for CD20 (original magnification ×2; inset, original magnification ×20), (F) had Kappa light chain restriction (original magnification ×40), and (G) were negative for Lambda light chain (original magnification ×40).