Our findings highlight the genetic and epigenetic homogeneity of <i>IGH</i>::<i>BCL3</i>-translocated CLL samples and their differences from other types of CLL, suggesting <i>IGH</i>::<i>BCL3</i> leukemic B-cell neoplasms to be a biological distinct type within the spectrum of mature lymphatic leukemia/CLL. Here, BCL3 is linked to B-cell chronic lymphocytic leukemia.