A distinctive characteristic of CLL LN tissues is the presence of pseudofollicles.28,29 These are proliferation centers that have not been described in other lymphoproliferative conditions and are enriched in CD40L+ T cells and Ki-67+ CLL cells compared with surrounding tissue.30 The emergence of follicle-like structures after prolonged culture in the model could indicate a similar phenotype. This evidence concerns the gene MKI67 and B-cell chronic lymphocytic leukemia.