Immunohistochemical detection of follicular dendritic cells in the diagnosis of small B-cell lymphomas

Our study included 46 cases of B-chronic lymphocytic leukemia/small lymphocytic lymphoma (B-CLL/SLL), 25 mantle cell lymphomas (MCL), and 40 follicular lymphomas (FL). The lymphomas were diagnosed according to current morphological, immunohistochemical, and in some cases molecular-genetic criteria. The patterns of follicular dendritie cells (FDCs) were studied in paraffin sections using the anti CD21, anti CD23, and CNA.42 antibodies. The differences in staining patterns of FDCs among the studied lymphomas were statistically significant. The absence or small number of FDC clusters are typical of B-CLL/SLL, while FDC meshwork limited to peripheral parts of neoplastic follicles is characteristic for FL. In contrast, MCL is characterized by irregular FDC meshwork or by FDC clusters present in the centres of residual follicles. Thus, we have demonstrated that the patterns of FDCs is an independent diagnostic feature for distinguishing between B-CLL, FL, and MCL.