Cyclin D1 negative MCL cases lack cyclin D1 andCCND1 rearrangements and may haveCCND2 rearrangements or genetic alterations leading to overexpression of cyclin D2 and cyclin D3 or rarely due to truncated cyclin D1 mRNA.15 SOX11 (>90%) helps to identify CD5 and cyclin D1 negative cases. This evidence concerns the gene CD5 and mantle cell lymphoma.