The findings from our unique case of composite lymphoma in which FL, SLL and high-grade B-cell lymphoma with rearrangement of MYC and BCL2 co-existed within a single, small tissue fragment suggest that the FL and SLL/CLL processes represent distinct neoplastic clones and that the high-grade B-cell component emerged through direct clonal evolution from the FL in a process that entailed acquisition of an IGH-MYC rearrangement. This evidence concerns the gene BCL2 and lymphoma.