A recently recognized variant of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) expressing somatic hypermutations of the Immunoglobulin heavy chain (IGH) genes. The recognition of this variant alters the belief that CLL/SLL is always derived from a naive, pregerminal center B-cell. The presence of somatic hypermutations of IGH genes occurs in approximately 50% of CLL/SLL cases and implies a postgerminal center, memory origin. Patients with this variant of CLL/SLL have a favorable prognosis, with a reported median survival of more than 24 years.