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

Figure 1

Case 1: lymph node biopsy showing relapsed splenic marginal zone lymphoma with prolymphocytic transformation and acquired CD5 (dim) and cyclin D1 (diffuse, strong) expression. Lymphoma cells consist of both small lymphoid cells with condensed nuclear chromatin, nuclear membrane irregularities, and monocytoid features and transformed cells with prolymphocytic features including intermediate to large size, more abundant cytoplasm, and prominent nucleoli (a, b). Lymphoma cells expressed CD20 (c), were negative for CD3 (d), a subset expressed dim CD5 (e), and cyclin D1 expression was diffuse and strong (f). (a and b) Hematoxylin and eosin staining, (a) 100 times magnification, (b) 500 times magnification, (c, d, and f) 200 times magnification, (e) 400 times magnification, and inset in (f) 1000 times magnification.

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