Figure 4: (a) Neoplastic lymphoid cells showing a lack of immunoreactivity for AE1/AE3, which assists in ruling out carcinoma (AE1/AE3; 100x magnification). (b) and (c) CD5 and CD20, respectively, demonstrate that the cell lineage for the neoplastic lymphocytes is the B lymphocyte with aberrant coimmunoreactivity with CD5. (CD5; CD20; 100x magnification). (d) Cyclin D1 staining positivity in the neoplastic cells is strongly associated with mantle cell lymphoma (Cyclin D1; 100x magnification).