MS4A1 and B-cell chronic lymphocytic leukemia: In the recent International Consensus Classification (ICC) and the 5th edition of the World Health Organization Classification (WHO HAEM5), the diagnostic criteria for CLL/small lymphocytic lymphoma (SLL) are the same and include the coexistence of CD19, CD20, CD5, and CD23 antigens on the leukemic cells [7,8].