A commercially available specific marker of SMZL is lacking, and the immunophenotypical profile of SMZL is currently mainly defined on the basis on the lack of expression of markers associated with its mimickers (follicular lymphoma, mantle cell lymphoma, B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma, hairy cell leukemia), including CD5, CD10, CD23, cyclin D1, CD25, CD11c, and Annexin A1 to name just a few. Here, FCER2 is linked to mantle cell lymphoma.