B-cell chronic lymphocytic leukemia (CLL) is a lymphoproliferative disorder manifested by a clonal expansion of mature, long-lived, B lymphocytes. The disease is identical to small lymphocytic leukemia (SLL); the clinical distinction is whether the leukemic (blood and marrow) or the nodal components of the disease predominate in a given patient. The 2001 World Health Organization classification scheme considers CLL and SLL in one category (CLL/SLL) because of shared clinicopathologic features. The mechanisms of why clonal B cells predominate in marrow or node are not clearly understood, but one possibility may be the ability of B lymphocytes to "home" to certain . . . [Full Text of this Article]