Splenic B-Cell Lymphomas with Diffuse Cyclin D1 Protein Expression and Increased Prolymphocytic Cells: A Previously Unrecognized Diagnostic Pitfall

Figure 2

Case 1: splenic marginal zone lymphoma and staging bone marrow biopsy. Lymphoma cells are seen in a micronodular distribution expanding splenic white pulp and infiltrating adjacent red pulp (a) and are small with monocytoid morphologic features and minimal cytologic atypia (b). Tumor cells expressed CD20 (not shown) and were negative for CD5 and cyclin D1 (c and d). Bone marrow staging biopsy showed extensive involvement by lymphoma present predominantly in an interstitial nodular distribution with a focal sinusoidal pattern of involvement (inset in (e) showing focal sinusoidal distribution). Lymphoma cells were small in size and prolymphocytic or large cell transformation was not seen (f). (a, b, e, and f) Hematoxylin and eosin stain, (a and e) 100 times magnification, (b and f) 500 times magnification; CD5 (c) and cyclin D1 (d) immunohistochemistry stains shown at 400 and 200 times magnification, respectively.

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