Its cells exhibit the same immunophenotype (CD5+/CD19+ and CD5+/CD23+) and morphology as in CLL but does not primarily involve the bone marrow; as such, small lymphocytic lymphoma (SLL) is classified as a combined lymphoproliferative disease, i.e., as SLL/CLL [4]. Here, FCER2 is linked to B-cell chronic lymphocytic leukemia.